We provide atoms practice exercises, instructions, and a learning material that allows learners to study outside of the classroom. We focus on atoms skills mastery so, below you will get all questions that are also asking in the competition exam beside that classroom.

#### List of atoms Questions

Question No | Questions | Class |
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1 | The closest distance an ( alpha ) particle emitted can reach to the nucleus of an an atom is called A. Bohr’s number B. Distance of closest approach c. Atomic radius D. None of these | 12 |

2 | An electron in hydrogen atom stays in 2nd orbit for ( 10^{-8} ). How many, revolutions will it make till it jumps to the ground state? | 12 |

3 | Match List-I with List-II. | 12 |

4 | Corpuscles are the tiny particles of A. Light B. Sound c. waves D. Radiation | 12 |

5 | According to the Rutherford’s atomic model, the electrons inside the atom are A. stationary B. not stationary c. centralized D. None of these | 12 |

6 | Consider the spectral line resulting from the transition ( n=2 rightarrow n=1 ) in the atoms and ions given below. The shortest wavelength is produced by A. hydrogen atom B. deuterium atom c. singly ionized Helium D. doubly ionised Lithium | 12 |

7 | Hydrogen atom is excited from ground state to another state with principal quantum number equal to 4. Then the number of spectral lines in the emission spectra will be. A . 2 B. 3 c. 5 D. 6 | 12 |

8 | The radius of oxygen nucleus ( left(_{8} O^{16}right) ) is ( 2.8 times 10^{-15} mathrm{m} . ) Calculate the radius of the lead nucleus. | 12 |

9 | Photoelectric effect was successfully explained by A. Planck B. Hallwash c. Hertz D. Einstein | 12 |

10 | With increasing quantum number, the energy difference between adjacent energy levels in atoms A . decreases B. increases c. remains constant D. decreases for low ( Z ) and increases for high ( Z ) | 12 |

11 | Find the wavelength of the most energetic photons in this series. A . ( 1800 AA ) в. 1500 А c. ( 1300 AA ) D. 1650 A | 12 |

12 | How the linear velocity ‘v’ of an electron in the Bohr orbit is related to its quantum number ‘n’? A ( cdot v propto frac{1}{n} ) в. ( v propto frac{1}{n^{2}} ) c. ( _{v} propto frac{1}{sqrt{n}} ) D. ( v propto n ) | 12 |

13 | Atomic hydrogen is excited to the nth energy level.The maximum number of spectral lines which it can emit while returing to the ground state, is A ( cdot frac{1}{2} n(n-1) ) B . ( frac{1}{2} n(n+1) ) c. ( n(n+1) ) D. ( n(n-1) ) | 12 |

14 | The figure above represents some of the lower energy levels of the hydrogen atom in simplified form. If the transition of an electron from ( boldsymbol{E}_{mathbf{4}} ) to ( E_{2} ) were associated with the emission of blue light, which one of the following transitions could be associated with the emission of red light? ( mathbf{A} cdot E_{4} ) to ( E_{1} ) B ( . E_{3} ) to ( E_{1} ) ( mathbf{c} cdot E_{3} ) to ( E_{2} ) D. ( E_{1} ) to ( E_{3} ) | 12 |

15 | The first artificial transmutation was observed by Rutherford. If true enter 1 else enter 0 | 12 |

16 | The angular speed of the electron in the ( boldsymbol{n}^{t h} ) Bohr orbit of the hydrogen at om is proportional to ( A cdot n ) B ( cdot n^{3} ) c. ( frac{1}{n} ) D. ( frac{1}{n^{3}} ) | 12 |

17 | The ionization energy of hydrogen atom is ( 13.6 e V . ) Hydrogen atoms in the ground state are excited by electromagnetic radiation of energy 12.1 ( e V ). How many spectral lines will be emitted by the hydrogen atoms? A. one B. two c. three D. four | 12 |

18 | according to Ruther-fordis atomic model, the mass of the atom is evenly distributed throughout the atom A. True B. False | 12 |

19 | The wave number of first line of Balmer series of hydrogen atom is ( 15200 mathrm{cm}^{-1} ) What is the wave number of first line of Balmer series of ( L i^{2+} ) ion. A. ( 15200 mathrm{cm}^{-1} ) В. ( 136800 m^{-1} ) c. ( 76000 mathrm{cm}^{-1} ) D. ( 13680 mathrm{cm}^{-1} ) | 12 |

20 | The number of neutrons in an atom ( boldsymbol{X} ) of atomic number ( Z ) and mass number ( boldsymbol{A} ) is A . zero в. ( Z ) c. ( A-Z ) D. | 12 |

21 | The mass number of a nucleus is: A. Always less than atomic number B. Always more than atomic number C. Equal to atomic number D. More than or equal to atomic number | 12 |

22 | The incident photon involved in the photo-electric effect experiment ( nu>nu_{o} ) A. Completely disappears B. Comes out with increased frequency c. comes out with a decreased frequency D. Comes out with out change in frequency | 12 |

23 | In Bohr’s model of the hydrogen atom, let ( R, V, T ) and ( E ) represent the radius of the orbit, speed of the electron, time period of revolution of electron and the total energy of the electron respectively. The quantity proportional to the quantum number n is ( mathbf{A} cdot V R ) в. ( E ) ( c ) D. ( T ) | 12 |

24 | Rutherford’s alpha-particle scattering experiment was responsible for the discovery of: A. atomic nucleus B. electron. c. proton D. neutron. | 12 |

25 | A ( 100 e V ) electron collides with a stationary helium ion ( left(H e^{+}right) ) in its ground state and excites to a higher level. After the collision, ( boldsymbol{H} e^{+} ) ion emits two photons in succession with wavelengths ( 1085 A ) and 304 A. Find the principal quantum number of the excited state. Also, calculate the energy of the electron after the collision. Given ( boldsymbol{h}=mathbf{6 . 6 3} times mathbf{1 0}^{-mathbf{3 4} mathbf{J}} boldsymbol{s} ) | 12 |

26 | Let ( v_{1} ) be the frequency of the series limited of the Lyman series, ( v_{2} ) be the frequency of the first line of the Lyman series, and ( v_{3} ) be the frequency of the series limited of the Balmer series. Then: A. ( v_{1}-v_{2}=v_{3} ) В. ( v_{2}-v_{1}=v_{3} ) C ( cdot v_{3}=frac{1}{2}left(v_{1}+v_{3}right) ) D. ( v_{1}+v_{2}=v_{3} ) | 12 |

27 | What are the Cathode Rays? | 12 |

28 | When electronjumps from ( n=4 ) level to ( n=1 ) level, the angular momentum of electron changes by ( ^{A} cdot frac{h}{2 pi} ) в. ( frac{2 h}{2 pi} ) c. ( frac{3 h}{2 pi} ) D. ( frac{4 h}{2 pi} ) | 12 |

29 | The ratio of the energies of the hydrogen atom in its first to second excited state is A ( cdot 1 / 4 ) в. ( 4 / 9 ) c. ( 9 / 4 ) D. | 12 |

30 | If the radius of gold (Au) and platinum ( (P t) ) atoms in ( p m ) is ( 100 sqrt{2} ) and ( 90 sqrt{2} ) respectively, find ( n_{A u} n_{P t} ) A . 0.52 B. 0.68 c. 0.73 D. 0.74 | 12 |

31 | The element which was observed in solar spectrum is A. Helium B. Xenon c. Neon D. Argon | 12 |

32 | If ( E_{P} ) and ( E_{k} ) represent potential energy and kinetic energy respectively, of an orbital electron, then according to Bohr’s theory: A ( . E_{k}=-E_{p} / 2 ) B. ( E_{k}=-E_{p} ) c. ( E_{k}=-2 E_{p} ) D. ( E_{k}=2 E_{p} ) | 12 |

33 | Rutherford’s scattering experiment led to the discovery of : A. nucleus B. presence of neutrons in the nucleus ( c cdot ) both (1) and (2) D. revolving nature of electrons around the nucleus | 12 |

34 | When a silver foil (Z=47) was used in an ( alpha ) -ray scattering experiment, the number of ( alpha ) partied scattered at ( 30^{circ} ) aws found to be 200 per minute. If the silver foil is replaced by aluminium ( (z=13) ) foil of same thickness, the number of ( alpha ) -particles scattered per minute at ( 30^{circ} ) is nearly equal to A . 15 B. 30 c. 10 D. 26 | 12 |

35 | Rutherford’s model explains: This question has multiple correct options A. Atom is a planetary model B. Electrons never loose nor gain energy. C. Electron revolves around the nucleus with high velocities to counterbalance the forces of electrostatic forces of attraction between protons and electrons. D. Electrons do not move at all. | 12 |

36 | In the region of space ( dot{E} ) and ( dot{B} ) are parallel. A beam of cathode-rays moving in the same direction as ( dot{E} ) enters the space. Which of the following conclusions is correct A. The cathode rays will travel straight B. The cathode rays wil lbe deflected towards right c. The speed of cathode ray particles increases D. The speed of cathode ray particles decreases | 12 |

37 | Cathode rays A. Are the atoms moving toward the cathode B. Are electromagnetic waves C. Are negative ions travelling from cathode to anode D. Are electrons emitted by cathode and travelling towards anode | 12 |

38 | For Bohr’s model of the hydrogen atom, the energy of the electron in its ground state is found to be ( -13.6 e V ). (i) Draw an energy level diagram for the hydrogen atom and mark the values of energy (in eV) at ( n=2 ) to ( n=infty ) to. Obtain the maximum energy of a photon emitted by the hydrogen atom in ( mathrm{eV} ) | 12 |

39 | Which of the following conclusions regarding the structure of atom is based on Rutherford’s ( alpha ) -particle scattering experiment? A. Th positive charge is concentrated in a very smal volume of the atom B. The positive charge is scattered with the electrons throughout the atom. c. The volume occupied by the nucleus is half of the volume of atom. D. Most of the space in the atom is occupied by the neutrons | 12 |

40 | The number of waves in the third orbit of H atom is ( mathbf{A} cdot mathbf{1} ) B. 2 ( c cdot 4 ) ( D ) | 12 |

41 | The diagram show the energy levels for an electron in a certain atom. Which transition shown represents the emission of a photon with the most energy? ( A ) B. III ( c ) 2. | 12 |

42 | Which of the following is/are true for Thomson’s model of atom? This question has multiple correct options A. The radius of an electron can be calculated by using this model B. In an undisturbed atom, the electron will be at their equilibrium position within the sphere C. The cloud of positive charge and the electrons balances their mutual charge D. None of the above | 12 |

43 | If an electron in hydrogen atom jumps from an orbit of level ( n=3 ) to an orbit of level ( n=2 ), emitted radiation has a frequency (R=Rydberg’s constant, C=velocity of light) ( ^{A} cdot frac{3 R C}{27} ) в. ( frac{R C}{25} ) c. ( frac{8 R C}{9} ) D. ( frac{5 R C}{36} ) | 12 |

44 | The possible values of orbital quantum numbers are: ( [n text { is the principle quantum number }] ) ( A cdot ) from 0 to ( (n-1) ) B. from 0 to ( n ) ( c cdot ) from 0 to ( (n+1) ) D. all of the above | 12 |

45 | In a cathode ray tube, what is the effect on the beam of particles if the anode voltage is increased? A. Kinetic Energy of electron beam increase B. Rate of electron emission increase c. Kinetic energy of electron beam remains unchanged D. Rate of electron emission decrease | 12 |

46 | What is the major ( X ) -ray emitted by the sample? A ( . K_{alpha} ) в. ( K_{beta} ) c. ( K_{gamma} ) D. ( K_{delta} ) | 12 |

47 | What was the initial speed of the alpha particle? A ( cdot 132 . times 10^{2} m s^{-1} ) В. ( 1.32 . times 10^{7} mathrm{ms}^{-1} ) c. ( 13.2 . times 10^{2} m s^{-1} ) D. ( 0.13 . times 10^{7} mathrm{ms}^{-1} ) | 12 |

48 | State whether true or false: Atoms normally have equal number of protons and electrons A. True B. False | 12 |

49 | The difference between the atom ( U^{235} ) and ( U^{238} ) is that B. ( U^{238} ) contains 3neutrons and 3 electrons more c. ( U^{238} ) contains 3 protons more D. ( U^{238} ) contains 3 proton and 3 electron more | 12 |

50 | Rutherford was the first physicist to carry artificial transmutation from one element into another. In his experiment he bombarded nitrogen with alpha particles to produce isotope of A. Hydrogen B. Carbon c. oxygen D. Helium | 12 |

51 | If the difference between ( (boldsymbol{n}+mathbf{1})^{t h} ) Bohr radius and ( n^{t h} ) Bohr radius is equal to the ( (boldsymbol{n}-mathbf{1})^{t h} ) Bohr radius then find the value of ( n ) A . 4 B. 3 c. 2 D. | 12 |

52 | A hydrogen atom in a state having a binding energy of ( 0.85 e V ) makes transition to a state with excitation energy ( 10.2 e V ) Find the wavelength of the emitted | 12 |

53 | What is the effect on the thermion beam in a cathode ray tube if the anode voltage value is reduced but remains above zero? | 12 |

54 | which of the following statements are true w.r.t. ruthenford’s model of an atom This question has multiple correct options A. Most of the space inside an atom is empty. B. The positively changed centre is confined to a very small space inside an atom. C. negatively charged electrons revolve around nucleus in particular orbits. D. Atomic mass is evenly distributed throughout the atom | 12 |

55 | The ionisation potential of hydrogen atom is ( -13.6 mathrm{eV} ). An electron in the ground state of a hydrogen atoms absorb a photon of energy ( 12.75 mathrm{eV} . ) How many different spectral line can one expect when the electron make a downward transition? ( A ) B. 4 ( c cdot 2 ) D. 6 | 12 |

56 | An electron of stationary hydrogen atom jumps from 4 th energy level to ground level. The velocity that the photon acquired as a result of electron transition will be (h = Planck’s constant, ( mathrm{R}= ) Rydberg’s constant, ( mathrm{m}= ) mass of photon) A ( cdot frac{9 R h}{16 m} ) в. ( frac{11 h R}{16 m} ) c. ( frac{13 h R}{16 m} ) D. ( frac{15 h R}{16 m} ) | 12 |

57 | ( alpha ) -particle consists of : A. 2 protons and 2 neutrons only B. 2 electrons, 2 protons and 2 neutrons C ( . ) 2 electrons and 4 protons only D. 2 protons only | 12 |

58 | If element with principal quantum number ( n>4 ) were not allowed in nature, the number of possible elements would be ( mathbf{A} cdot 60 ) B. 32 ( c cdot 4 ) D. 64 | 12 |

59 | Can we use a screen coated with barium platinocyanide in a cathode ray tube? If so what effects do we observe on the screen? | 12 |

60 | In an atom an electron excites to the fourth orbit.When it jumps back to the energy level one a spectrum is formed. Total number of spectral lines in this spectrum would be ( A cdot 3 ) B. 4 ( c cdot 5 ) D. 6 | 12 |

61 | The ratio of momenta of an electron and a ( alpha ) -particle which is accelerated from rest by a potential difference of ( 100 mathrm{V} ) is: ( A ) в. ( sqrt{frac{2 m_{e}}{m_{alpha}}} ) c. ( sqrt{frac{m_{e}}{m_{alpha}}} ) D. ( sqrt{frac{m_{e}}{2 m_{alpha}}} ) | 12 |

62 | One atomic mass unit (amu) is approximately equal to A . ( 931.4 mathrm{MeV} ) B . ( 251.2 mathrm{MeV} ) c. ( 120.4 mathrm{MeV} ) D. ( 170.5 mathrm{MeV} ) | 12 |

63 | An ( alpha- ) particle passes through a potential difference of ( 2 times 10^{6} V ) and then it becomes incident on a silver foil. The charge number of silver is ( 47 . ) The energy of incident particles will be (in joules) A ( .5 times 10^{-12} ) B. ( 6.4 times 10^{-13} ) c. ( 5.8 times 10^{-14} ) D. ( 9.1 times 10^{-15} ) | 12 |

64 | The energy required to transfer an electron from second Bohr’s orbit to third Bohr’s orbit in a hydrogen- like atom with nuclear charge ( Z_{e} ) is ( 68 . e V . ) The value of ( Z ) will be. ( A cdot 3 ) B. 4 ( c .5 ) D. 6 | 12 |

65 | How many wavelengths of ( K r^{86} ) are contained in one meter? A . 1553164.13 B. 652189.63 c. 2347127.23 D. 1650763.73 | 12 |

66 | Rutherford’s scattering experiment is related to the size of the: A. nucleus B. atom c. electron D. neutron | 12 |

67 | In an electron gun the control grid is given a negative potential relative to cathode in order to A. Decelerate electrons B. Repel electrons and thus to control the number of electrons passing through it c. To select electrons of same velocity and to converge them along the axis D. To decrease the kinetic energy of electrons | 12 |

68 | The distance of closest approach of the particle to the nucleus will be A ( cdot 6.4 times 10^{-13} mathrm{m} ) B . ( 4.3 times 10^{-13} mathrm{m} ) c. ( 2.1 times 10^{-13} mathrm{m} ) D. ( 3.4 times 10^{-14} mathrm{m} ) | 12 |

69 | The nuclear radius of ( _{4} B e^{8} ) nucleus is : A ( cdot 1.3 times 10^{-15} mathrm{m} ) B . 2.6 ( times 10^{-15} mathrm{m} ) c. ( 1.3 times 10^{-13} ) и D. 2.6 ( times 10^{-13} mathrm{m} ) | 12 |

70 | In ( 1899, ) Ernest Rutherford studied the absorption of radioactivity by thin sheets of metal foil and found two components: A. alpha radiation and beta radiation B. gamma radiation and beta radiation c. alpha radiation and gamma radiation D. none of the above | 12 |

71 | The specific charge for cathode rays is A. Constant B. Variable c. Depend upon the material of the cathode D. Depend upon the nature of the gas in the discharge tube | 12 |

72 | Suppose that the potential energy of a hypothetical atom consisting of a proton and an electron is given by ( mathrm{U}=- ) ( mathrm{Ke}^{2} / 3 mathrm{r}^{3} . ) Then if Bhor’s postulates are applied to this atom, then the radius of the ( n^{t h} ) orbit will be proportional to: ( A cdot n^{2} ) ( B cdot 1 / n^{2} ) ( c cdot n^{3} ) ( D cdot 1 / n^{3} ) | 12 |

73 | What is minimum frequency of the photon required to carry out transition A ( cdot 1.21 times 10^{15} H z ) B . ( 1.61 times 10^{15} mathrm{Hz} ) c. ( 1.21 times 10^{14} H z ) D. ( 1.61 times 10^{14} mathrm{Hz} ) | 12 |

74 | What is the wavelength of the most energetic photon emitted in the Balmer’s series of the hydrogen atom? A . 3694 A в. 5756 А c. 3333 А D. 3669 A | 12 |

75 | ( ln L i^{++}, ) electron in first Bohr orbit is excited to a level by a radiation of wavelength ( lambda ). when the ion gets deexcited to the ground state in all possible ways (including intermediate emissions), a total of six spectral lines are observed. What is the value of ( lambda ) ? (Given ( : boldsymbol{h}=mathbf{6 . 6 3} times mathbf{1 0}^{mathbf{3 4} mathbf{J}} mathbf{s} ; quad mathbf{l}, mathbf{c}=mathbf{3} ) ltimes ( 10^{wedge} 8 mathrm{ms}^{wedge}{-13 $ $) ) ( mathbf{A} cdot 9.4 n m ) в. ( 12.3 n m ) ( c .10 .8 n m ) D. ( 11.4 n m ) | 12 |

76 | Which of the following statement about hydrogen spectrum are correct? This question has multiple correct options A. All the lines of Lyman series lie in ultraviolet region B. All the lines of Balmer series lie in visible region C. All the lines of Paschen series lie in infrared region D. None of the above | 12 |

77 | When an electron in hydrogen atom jumps from the excited state to the ground state, how would the de-Broglie wavelength associate with the electron change? Justify your answer | 12 |

78 | The fine structure of hydrogen spectrum can be explained by A. the presence of neutrons in the nucleus B. the finite size of nucleus c. the orbital angular momentum of electrons D. the spin angular momentum of electrons | 12 |

79 | Write three conclusion made by Rutherford on the basis of alpha particle scattering experiment. | 12 |

80 | According to classical theory of Rutherford, atom is A. unstable B. stable C. positive D. partially stable | 12 |

81 | Calculate the radius of oxygen nucleus. Given that ( boldsymbol{R}_{boldsymbol{o}}=mathbf{1 . 1} times mathbf{1 0}^{-mathbf{1 6}} mathbf{m} ) | 12 |

82 | The ( K E ) of the electron in an orbit of radius ( r ) in hydrogen atom is : ( (e= ) electric charge) ( ^{A} cdot frac{e^{2}}{r^{2}} ) в. ( frac{e^{2}}{2 r} ) ( c cdot frac{e^{2}}{r} ) D. ( frac{e^{2}}{2 r^{2}} ) | 12 |

83 | The ratio of wavelengths of the last line of Balmer series and the last line of Lyman series is A .2: 1 B. 1: 2 c. 4: 1 D. 2: 6 | 12 |

84 | Consider the following statements: (A) Nuclear force is chargeindependent. (B) Radioactivity which is the spontaneous emission of ( (boldsymbol{alpha}, boldsymbol{beta}, boldsymbol{gamma}) ) particles is often influenced by chemical or physical processes. (C) A free neutron is unstable whereas a free proton is stable. (D) Half-life time of ( x ) radioactive element is fifty percent of its average life period. Which of the above statement/s is/are correct? ( A cdot(A) ) only B. (A) and (C) c. ( (A),(C) ) and ( (D) ) D. (B) and (C) | 12 |

85 | The values of ( n_{1} ) and ( n_{2} ) for Pfund’s series are A ( cdot n_{1}=5, n_{2}=6,7 ) В . ( n_{1}=4, n_{2}=5,6,7 . . . ) C ( . n_{1}=3, n_{2}=4,5,6 dots ) D. ( n_{1}=2, n_{2}=3,4,5 dots ) | 12 |

86 | What does J J Thomson model failed to explain- A. scattering of Alpha particles B. neutality of atom ( c . ) both of above D. none of these | 12 |

87 | In a laser tube, all the photons A. have same wavelength B. have same energy c. move in same direction D. move with same speed | 12 |

88 | An electron and a proton are separated by a distance ( r ) so that the potential energy between them is ( U=k log r ) where ( k ) is a constant. The expression for various energy levels of the above said hypothetical atom is: ( ^{mathbf{A}} cdot frac{k}{2}left[1+log frac{n^{2} h^{2}}{4 pi^{2} m k}right] ) в. ( 2 kleft[2+log frac{n^{2} h^{2}}{4 pi^{2} m k}right] ) ( c cdot kleft[2+log frac{n^{2} h^{2}}{4 pi^{2} m k}right] ) D. ( frac{k}{2}left[1+log frac{n^{2} h^{2}}{2 pi^{2} m k}right. ) | 12 |

89 | According to the quantum theory of light, the energy of light is carried in discrete units called A. alpha particles B. photoelectrons c. protons D. photons | 12 |

90 | What is the angular momentum of an electron in Bohr’s hydrogen atom whose energy is ( -3.4 e V ? ) ( ^{mathbf{A}} cdot_{L}=frac{h}{pi} ) B. ( L=frac{4 h}{pi} ) ( c cdot_{L}=frac{3 h}{pi} ) D. ( L=frac{5 h}{pi} ) | 12 |

91 | A photon of wavelength ( 300 mathrm{nm} ) interacts with a stationary hydrogen atom in ground state. During the interaction,whole energy of the photon is transferred to the electron of the atom. State which possibility is correct (Consider,Plancks constant ( =mathbf{4} times mathbf{1 0}^{-1 mathbf{1}} ) ( mathrm{eVs}, ) velocity of light ( =3 times 108 mathrm{m} / mathrm{s} ) ionization energy of hydrogen ( =13.6 mathrm{e} ) A. Electron will be knocked out of the atom B. Electron will go to any excited state of the atom c. Electron will go only to first excited state of the atom D. Electron will keep orbiting in the ground state of ato | 12 |

92 | A hydrogen-like atom (atomic number ( Z ) ) is in a higher excited state of quantum number ‘ ( n ) ‘. This excited atom can make a transition to the first excited state by successively emitting two photons of energies ( 10.2 e V ) and 17.0 ( e V ), respectively. Alternatively, the atom from the same excited state can make a transition to the second excited state by successively emitting two photons of energies ( 4.25 e V ) and ( 5.95 e V ) respectively. The values of ( n ) and ( Z ) are, respectively A. 6 and 6 B. 3 and 3 c. 6 and 3 D. 3 and 6 | 12 |

93 | An electron with K.E. ( 6 e V ) is incident on a hydrogen atom in its ground state.The collision: A. must be elastic B. may be partially elastic c. must be completly inelastic D. may be partially inelastic | 12 |

94 | As one considers orbits with higher values of ( n ) in a hydrogen atom, the electric potential energy of the atom A. decreases B. increases c. remains the same D. does not increase | 12 |

95 | In the Bohr model of a ( pi- ) mesic atom, a ( pi- ) meson of mass ( m_{pi} ) and of the same charge as the electron is in a circular orbit of radius ‘ ( r^{prime} ) about the nucleus with an orbital angular momentum ( h / 2 pi . ) If the radius of a nucleus of atomic number ( Z ) is given by ( boldsymbol{R}=mathbf{1 . 6} times mathbf{1 0}^{-15} boldsymbol{Z}^{frac{1}{3}} boldsymbol{m}, ) then the limit on ( Z ) for which ( left(epsilon_{0} h^{2} / pi m e^{2}=right. ) ( left.0.53 A text { and } m_{pi} / m_{e}=264right) pi- ) mesic atoms might exist is ( mathbf{A} cdot105 ) ( mathbf{c} .37 ) | 12 |

96 | Derive an expression for potential and kinetic energy of an electron in any orbit of a hydrogen atom according to Bohr’s atomic model. | 12 |

97 | Alpha-particles that come closer to nuclei in Rutherford’s alpha particle scattering experiment: A. are deflected more B. are deflected less c. make more collisions D. None of the above | 12 |

98 | Wavelengths of the first lines of the Lyman series, Paschen series and Balmer series in hydrogen spectrum are denoted by ( lambda_{L}, lambda_{P} ) and ( lambda_{B} ) respectively Arrange these wavelength in increasing order. | 12 |

99 | What principle is violated here? A . Laws of Motion B. Energy conservation c. Nothing is violated D. Cannot be decided | 12 |

100 | The ionization energy of ( L i^{++} ) is equal to ( mathbf{A} cdot 9 h c R ) в. ( 6 h c R ) ( mathbf{c} cdot 2 h c R ) D. ( h c R ) | 12 |

101 | An alpha particle of energy 5 MeV is scattered through ( 180^{circ} ) by a fixed uranium nucleus. The distance of the closest approach is of the order of A ( cdot 10^{-15} mathrm{cm} ) B . ( 10^{-13} mathrm{cm} ) ( mathbf{c} cdot 10^{-12} mathrm{cm} ) D. ( 10^{-19} mathrm{cm} ) | 12 |

102 | How does the ionization energy of an atom vary along a period and a group of the periodic table? | 12 |

103 | The path with which electron travels from ( y ) -plate to screen is A. Parabolic B. Hyperbolic C. Circular D. Straight line E . Helix | 12 |

104 | Fraunh offer line of the solar system is an example of: A. line absorption specturm B. emission of line system c. line emission spectrum D. emission of band spectrum | 12 |

105 | ( frac{sqrt{2}}{L} ) | 12 |

106 | In a cathode ray tube, what is the effect on the beam of particles if it passes through the electric field? A. the beam will get deflected towards the cathode B. the beam will get deflected towards the anode c. the beam will go undeflected D. None of the above | 12 |

107 | In a cubical vessel ( 1 m times 1 m times 1 m ) the gas molecules of diameter ( 1.7 times 10^{-8} mathrm{cm} ) are at a temperature ( 300 mathrm{K} ) and a pressure of ( 10^{-4} mathrm{mm} ) mercury. The mean free path of the gas molecule is A. 1 meter B. 4 meter c. 2.42 meter D. ( 1 mathrm{cm} ) | 12 |

108 | Calculate the wavelength of radiation emitted when electron in a hydrogen atom jumps from ( n=infty ) to ( boldsymbol{n}=mathbf{1} ) | 12 |

109 | A positroniuim consists of an electron and a positron revolving about their common centre of mass. Calculate the kinetic energy of the electron in ground state: A. 1.51 eV B. 3.4 eV c. ( 6.8 e V ) D. 13.6 eV | 12 |

110 | Assertion One will need a very powerful crane to lift a nuclear mass of even microscopic size. Reason The density of nucleus is very high. Read the above assertion and reason and choose the correct option regarding ¡t. A. The Assertion is correct but Reason is wrong B. The Assertion is wrong but Reason is correct c. Both Assertion and Reason are correct and Reason is the correct explanation of Assertion D. Both Assertion and Reason are correct but Reason is not the correct explanation of Assertion | 12 |

111 | An atom emits a spectral line of wavelength ( lambda ) when an electron makes a transition between levels of energy ( boldsymbol{E}_{1} ) and ( E_{2} . ) Which expression correctly relates ( lambda, E_{1} ) and ( E_{2} ? ) A ( cdot lambda=frac{h c}{E_{1}+E_{2}} ) B. ( lambda=frac{2 h c}{E_{1}+E_{2}} ) c. ( lambda=frac{2 h c}{E_{1}-E_{2}} ) D. ( lambda=frac{h c}{E_{1}-E_{2}} ) | 12 |

112 | Highly energetic electrons are bombarded on a target of an element containing 30 neutrons. The ratio of radii of nucleus to that of Helium nucleus is ( (14)^{1 / 3} . ) The atomic number of nucleus will be A . 25 B . 26 c. 56 D. 30 | 12 |

113 | The ratio of energies of first two excited states hydrogen atom is? ( A cdot 3 / 1 ) B. ( 1 / 4 ) ( c cdot 4 / 9 ) D. ( 9 / 4 ) | 12 |

114 | Which of the following series in the spectrum of hydrogen atom lies in the visible region of the electromagnetic spectrum? A. Paschen series B. Balmer series c. Lyman series D. Brackett series | 12 |

115 | The mass of photon at rest is A ( cdot h nu / e^{2} ) в. ( h nu / c ) c. ( h nu ) D. Zero | 12 |

116 | STRATION 29.5 Find the ratio of ionization energy of Bohr’s hydrogen atom and doubly ionized lithium ion (Li?). | 12 |

117 | The distance of closest approach of an alpha-particle fired towards a nucleus with momentum p is r. If the momentum of the alpha-particle is ( 2 p ) the corresponding distance of closest approach is : ( mathbf{A} cdot 4 r ) B . ( 2 r ) ( c cdot frac{2}{r} ) D. | 12 |

118 | A sample of hydrogen atoms gas contains 100 atoms ( A | ) the atoms are excited to the seventh state. The total energy released by all the atoms is ( frac{4800}{49} ) Ry( Where Ry ( =13 ) eV) then discuss the following things a) Maximum energy of the emitted photon will be less then ( frac{4800}{49} R y ) b)Maximum energy of the emitted photon may be grater than ( frac{48}{49} R y ) c)The value of ( n=6 ) d)total number of photon that can be emitted this sample may be less than 600 | 12 |

119 | What is the electronic configuration of phosphorus? A .2,8,5 B. 2, 8,4 c. 2,8,6 D. 2, 8, 3 | 12 |

120 | (a) Write the ( beta- ) decay of tritium in symbolic from. (b) Why is it experimentally found difficult to detect neutrinos in this process? | 12 |

121 | Rutherford experiment of scattering of ( alpha ) particles showed for the first time that the atom has | 12 |

122 | Which ray/radiation can be detected by GM counter? This question has multiple correct options A. Alpha B. Beta ( c cdot gamma operatorname{ray} ) D. al | 12 |

123 | Rutherford experiment of scattering of ( alpha ) particles showed for the first time that the atom has: A . electron B. protons c. nucleus D. all of these | 12 |

124 | If elements with principal quantum number ( n>4 ) were not allowed in nature, the number of possible elements would have been A . 32 B. 60 c. 18 ( D ) | 12 |

125 | According to Bohr’s model, if the kinetic energy of an electron in ( 2^{n d} ) orbit of ( H e^{+} ) is ( x, ) then what should be the ionisaion energy of the electron revolving in ( 3^{r d} ) orbit of ( m^{5+} ) ions ( > ) ( mathbf{A} cdot X ) в. ( 4 x ) c. ( x / 4 ) D. ( 2 X ) | 12 |

126 | A hydrogen-like atom has ground state binding energy ( 122.4 e V . ) Then This question has multiple correct options A. its atomic number is 3 B. an electron with 90 eV can excite it to a higher state c. an 80 eV electron can excite it to a higher state D. an electron of ( 8.2 mathrm{eV} ) and a photon of ( 91.8 mathrm{eV} ) emitted when a 100 eV electron interacts with it | 12 |

127 | State two uses of a cathode ray tube | 12 |

128 | An outstanding book on the wave nature of light titled “An Introduction to the Study of Wave Mechanics” was published in ( 1930 . ) Who was its author? A. E. Shroedinger B. A. Sommerfield c. P.A.M. Dirac D. Louis de Broglie | 12 |

129 | In interpreting Rutherford’s experiments on the scattering of alpha particles by thin foils, one must examine what the known factors were, and what the experiment concluded. Which of the following are true in this context? A. The number of electrons in the target atoms ( (i . e ., Z) ) was settled by these experiments B. The validity of Coulomb’s law for distances as small as ( 10^{-13} ) was known before these experiments. c. The experiments settled that size of the nucleus could not be larger than a certain value D. The experiments also settled that size of the nucleus could not be smaller than a certain value | 12 |

130 | Which of the following pair is correct? A. Rutherford; X-rays B. Roentgen;electron c. chadwick;neutron D. J-J-Thomson;photon | 12 |

131 | For an electron in the second orbit of Bohr’s hydrogen atom, the moment of linear momentum is: ( A cdot pi h ) в. ( 2 pi r h ) ( c cdot frac{h}{pi} ) D. ( frac{2 h}{pi} ) | 12 |

132 | The diagram above represents the energy states for a particular atom.Photons having which of the following energies could be absorbed by atoms of this kind in the ground state? Assume that the absorbed electrons do not ionize the atom. ( mathbf{A} cdot 7 e V ) B. 6 eV ( mathbf{c} .5 mathrm{eV} ) D. ( 4 e V ) ( mathrm{E} cdot 3 mathrm{eV} ) | 12 |

133 | If an element X has mass number and number of proton 8 then identify element ( X ) A . B. ( c cdot 0 ) D. Ar | 12 |

134 | When a hydrogen atom is raised from the ground state to an excited state. A. Both K.E. and P.E. increase B. Both K.E. and P.E. decrease c. The P.E. decreases and K.E. increases D. The P.E. increases and K.E. decreases | 12 |

135 | ( underbrace{k}_{k} ) | 12 |

136 | How can the brightness of the pattern on the screen of cathode ray tube be changed? A. Changing the target B. By changing the current on gridd c. By changing the negative potential on gridd D. can’t be changed | 12 |

137 | An alpha nucleus of energy ( frac{1}{2} m v^{2} ) is bombarded onto a heavy nuclear target of charge ( Z e . ) Then the distance of closest approach for the alpha nucleus will be proportional to ( mathbf{A} cdot v^{2} ) в. ( 1 / m ) c. ( 1 / v^{4} ) D. ( 1 / Z ) | 12 |

138 | Assertion Bohr had to postulate that the electrons in stationary orbits around the nucleus do not radiate. Reason According to classical physics all moving electrons radiate. A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion c. Assertion is correct but Reason is incorrect D. Assertion is incorrect but Reason is correct | 12 |

139 | Nucleons is the name given for and A. electron, neutron B. electron, proton c. nucleus, electron D. proton, neutron | 12 |

140 | A proton strikes another proton at rest with speed ( V_{0} . ) Assume impact parameter to be zero. Their closest distance of approach is (mass of proton is ( boldsymbol{m} ) ) ( ^{mathbf{A}} cdot frac{e^{2}}{4 pi varepsilon m v_{0}} ) в. ( frac{e^{2}}{pi varepsilon_{0} m v_{0}^{2}} ) c. ( frac{e^{2}}{m v_{0}^{2}} ) D. zero | 12 |

141 | The ratio of speed of electron in ground state of hydrogen atom to that of light is A ( cdot frac{1}{137} ) в. ( frac{1}{207} ) c. ( frac{2}{237} ) D. ( frac{1}{237} ) | 12 |

142 | An excited ( H e^{+} ) ion emits two photons in succession, with wavelengths ( 108.5 n m ) and ( 30.4 n m, ) in making a transition to ground state. The quantum number ( n, ) corresponding to its initial excited state is (for photon of wavelength ( lambda ), energy ( E=frac{1240 e V}{lambda(operatorname{in} n m)} ) ) ( mathbf{A} cdot n=5 ) B . ( n=4 ) ( mathbf{c} cdot n=6 ) D. ( n=7 ) | 12 |

143 | A mixture of ordinary hydrogen and its isotope, tritium (whose nucleus is approximately three times massive than ordinary hydrogen) is excited and its spectrum is studied. Calculate the shift in wavelength for the ( H_{alpha} ) lines in Balmer series. ( boldsymbol{R}_{infty}=mathbf{1 0 9 7 3 7 0 0 m}^{-1} ) mass of the proton ( M_{H}=1.67 times ) ( 10^{-27} k g, ) mass of electron, ( m=9.1 times ) ( 10^{-31} k g ) A ( cdot frac{6}{36} R_{H} ) в. ( frac{5}{36} R_{H} ) c. ( frac{7}{36} R_{H} ) D. ( frac{8}{36} R_{H} ) | 12 |

144 | During an ( alpha ) -decay, the atomic number of parent element and mass number 4 | 12 |

145 | In Millikan’s oil drop experiment, the charge of three oil drops ( X, Y ) and ( Z ) have been found to be 2,0.04 and 0.8 respectively. What could be the number of electrons attached to oil drop ( X ? ) A . 1 B . 20 c. 40 D. 50 | 12 |

146 | When Boron nucleus ( left(_{5}^{10} Bright) ) is bombarded by neutrons, ( boldsymbol{alpha}- ) particles are emitted. The resulting nucleus is of the element and has the mass number A. ( L i, 7 . ) B. ( L i, 8 . ) c. ( N a, 7 ) D. ( L i, 9 . ) | 12 |

147 | The maximum number of photons emitted by an H-atom,if atom is excited to states with principal quantum number four is A .4 B. 6 ( c cdot 2 ) ( D ) | 12 |

148 | State any two postulates of Bohr’s theory of hydrogen atom | 12 |

149 | According to Bohr hypothesis, discrete quantity is A. Momentum B. Angular velocity c. Potential energy D. Angular momentum | 12 |

150 | A beam of ( 13.0 e V ) electrons is used to bombard gaseous hydrogen. The series obtained in emission spectra is/are A. Lyman series B. Balmer series c. Brackett series D. All of these | 12 |

151 | In the Davisson and Germer experiment, the velocity of electrons emitted from the electron gun can be increased by A. increasing the potential difference between the anode and filament B. increasing the filament current c. decreasing the filament current D. decreasing the potential difference between the anode and filament | 12 |

152 | An electron makes a transition from ( boldsymbol{n}=mathbf{2} ) to ( boldsymbol{n}=mathbf{1} ) state in a hydrogen like atom This question has multiple correct options A. magnetic field at the site of nucleus is decreased by 16 times B. magnetic field at the site of nucleus is increased by 32 times c. angular momentum of electron is changed D. none of these | 12 |

153 | Assertion In Rutherford’s gold leaf experiment, most of the ( alpha ) particles passed through the foil Reason The entire positive charge and nearly all of the mass of an atom is concentrated in the nucleus A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion c. Assertion is correct but Reason is incorrect D. Both Assertion and Reason are incorrect | 12 |

154 | The ionization energy of ( L i^{2+} ) is equal to ( mathbf{A} cdot 9 h c R ) B. ( 6 h c R ) ( mathbf{c} cdot 2 h c R ) D. hcR | 12 |

155 | The difference between the wave number of ( 1^{s t} ) line of Balmer series of paschen series for ( L i^{2+} ) ion is: ( A cdot frac{R}{36} ) в. ( frac{5 R}{36} ) ( c .4 R ) D. ( frac{R}{4} ) | 12 |

156 | Who is given credit for coming up with the “plum pudding” model of the atom? A. Niels Bohr B. Earnest Rutherford c. J.J. Thompson D. James chadwick E. Max Planck | 12 |

157 | The ionization potential of hydrogen is ( 13.6 V . ) How much energy need to be supplied to ionize the hydrogen atom in the first excited state? A . ( 13.6 e V ) B. 27.2eV c. ( 3.4 e V ) D. ( 6.8 e V ) | 12 |

158 | Smallest particle in a chemical element or compound that has the chemical properties of that element or compound is ( A ). Atom B. Molecule c. Mixture D. Element | 12 |

159 | Identify which of the following element has a mass number of 20 and contains 11 neutrons? A. copper B. Gallium c. Calcium D. Sodium E. Fluorine | 12 |

160 | (a) Using Bohr’s postulates, obtain the expression for total energy of the electron in the ( n^{t h} ) orbit of hydrogen atom. (b) What is the significance of negative ( operatorname{sign} ) in the expression for the energy? (c) Draw the energy level diagram showing how the line spectra corresponding to Paschen series occur due to transition between energy levels. | 12 |

161 | The e/m ratio for electron was determined by : A. J.J Thomson B. Planck c. Einstein D. schrodinger | 12 |

162 | Name a device which is commonly used to convert an electric signal into a visual signal A. Cathode ray tube B. Transducer c. RMS converter D. None of the above | 12 |

163 | If an electron in a hydrogen atom has moved from ( n=1 ) to ( n=10 ) orbit, the potential energy of the system has: A. increased B. decreased c. remained unchanged D. become zero | 12 |

164 | The wavelengths involved in the spectrum of deuterium ( left(_{1}^{2} Dright) ) are slightly different from the hydrogen spectrum, because: A. Sizes of the two nuclei are different B. Nuclear forces are different in the two cases c. Masses of the two nuclei are different D. Attraction between the electron and the nucleus in different in the two cases | 12 |

165 | In an atom, there is ( 1 p^{+} ) and ( 1 e^{-} . ) If ( e^{-} ) revolves around the ( p^{+} ) then angular velocity is proportional to: ( mathbf{A} cdot r ) в. ( r^{3} ) c. ( frac{1}{r^{3 / 2}} ) D. ( frac{1}{r^{2}} ) | 12 |

166 | The radius of germanium (Ge) nuclide is measured to be twice the radius of Be the number of nucleons in Ge are | 12 |

167 | ( ln H ) -atm spectrum ( V ) is the wave number ( boldsymbol{V}_{1}=boldsymbol{V}_{min }+boldsymbol{V}_{max } ) for Lyman series ( boldsymbol{V}_{1}=boldsymbol{V}_{min }+boldsymbol{V}_{max } ) for Balmer series then ( V_{1}: V_{2} ) A . 9: 2 B. 3: 2 ( c .5: 2 ) D. 7: 2 | 12 |

168 | From Rutherford’s alpha particle scattering experiment give the experimental evidence for deriving the conclusion that | 12 |

169 | Let ( boldsymbol{v}_{boldsymbol{K}_{alpha}}, boldsymbol{v}_{boldsymbol{K}_{beta}}, ) and ( boldsymbol{v}_{boldsymbol{L}_{alpha}} ) are the frequencies of ( boldsymbol{K}_{boldsymbol{alpha}}, boldsymbol{K}_{boldsymbol{beta}} ) and ( boldsymbol{L}_{boldsymbol{alpha}} . mathbf{X} ) raylines of a material, then ( mathbf{A} cdot v_{K_{alpha}}+v_{K_{beta}}=v_{L_{alpha}} ) В . ( v_{K_{a}}-v_{K_{beta}}=v_{l_{d}} ) ( mathbf{c} cdot v_{L_{alpha}}+v_{K_{alpha}}=v_{K_{beta}} ) D. ( v_{K_{alpha}}-v_{L_{alpha}}=v_{K_{beta}} ) | 12 |

170 | Describe the drawback of Rutherford’s model of atom. | 12 |

171 | A proton and an alpha particle having the same kinetic energy are allowed to pass through a uniform magnetic field perpendicular to the direction of their motion. Compare the radii of the paths of proton and alpha particle. | 12 |

172 | In Rutherford experiment, most of the alpha particles go straight through the foil because A. alpha particles are much heavier than electron B. alpha particles are positively charged c. alpha particles move with high velocity D. most part of the atom is empty | 12 |

173 | Name a material which exhibits fluorescence when cathode rays fall on ¡t. | 12 |

174 | An electron in the ground state of hydrogen has an angular momentum ( L_{1} ) and an electron in the first excited state of lithium has an angular momentum ( boldsymbol{L}_{2} . ) Then A ( cdot L_{1}=L_{2} ) В. ( L_{1}=4 L_{2} ) ( mathbf{c} cdot L_{2}=2 L_{1} ) D. ( L_{1}=2 L_{2} ) | 12 |

175 | If the closest distance of approach for an ( alpha ) particle when it is radiated upon an element of atomic no.40, is ( 10^{-14} m ) then find the initial ( K E ) of the ( alpha ) particles. | 12 |

176 | ( M, M_{n} ) and ( M_{p} ) denotes the masses of a nucleus of ( z X^{A}, ) a neutron, and a proton respectively. If the nucleus is separated into its individual protons and neutrons then, A ( cdot M=(A-Z) M_{n}+Z M_{p} ) B. ( M=Z M_{n}+(A-Z) M_{p} ) C. ( M>(A-Z) M_{n}+Z M_{p} ) D. ( M<(A-Z) M_{n}+Z M_{p} ) | 12 |

177 | Total energy of an electron in the ground state of hydrogen atom is ( -13.6 e V ). Its total energy, when hydrogen atom is in the first excited state, is: ( mathbf{A} cdot+13.6 mathrm{eV} ) B. ( +3.4 e V ) c. ( -3.4 e V ) D. ( -54.4 e V ) | 12 |

178 | An element X has mass number ( 10, ) and number of neutrons = 7. Then what will be the number of proton? A . 10 B. 3 c. 7 D. 17 | 12 |

179 | Among the following particles, belongs to baryons. A. neutron B. ( mu ) -meson c. positron D. Pi-meson | 12 |

180 | Using Bohr’s atomic model, derive an equation for radius of orbit of an electron. | 12 |

181 | What is the ratio of the shortest wavelength of the Balmer series to the shortest wavelength of the Lyman series ( ? ) ( A cdot 4: ) B. 4: 9 ( c cdot 4: 3 ) D. 5 : 9 | 12 |

182 | Number of spectral line in hydrogen atom is A. 6 B. 8 c. 15 D. None of the above | 12 |

183 | In Rutherford’s atomic model, the electrostatic force of attraction between the positively and negatively charged particles is counter balanced by: A. The centripetal force exerted on the electrons moving in circular path B. The high velocity of the electrons moving in a circular path c. The linear movement of the nucleus D. None of these | 12 |

184 | The transition from the state ( n=4 ) to ( boldsymbol{n}=mathbf{3} ) in hydrogen-like atom results in ultraviolet radiation. Infrared radiation will be obtained in the transition from? | 12 |

185 | A gas of monoatomic hydrogen is bombarded with a stream of electrons that have been accelerated from rest through a potential difference of ( 12.75 V . ) In the emission spectrum one cannot observe any line of A. Lyman series B. Balmer series c. Paschen series D. Pfund series | 12 |

186 | In a CRT the acceleration of electrons is controlled by changing between the cathode and anode. A. potential difference B. space c. temperature D. none of these | 12 |

187 | Which person had convinced people on the fact that matter could be divided forever? A. Dalton B. Democritus c. Thomson D. Aristotle E. Rutherford | 12 |

188 | Which transition will occur when a hydrogen atom is irradiated with radiation of wavelength 103 nm? ( A ) B. ( I I ) ( c . I V ) ( D ) | 12 |

189 | Calculate the shortest and longest wavelengths of Balmer series of hydrogen atom. Given ( boldsymbol{R}=mathbf{1 . 0 9 7} times ) ( 10^{7} m^{-1} ) | 12 |

190 | The time by a photo-electron to come out after the photon strikes is approximately ( mathbf{A} cdot 10^{-1} s ) B. ( 10^{-4} s ) ( mathbf{c} cdot 10^{-10} s ) D. ( 10^{-16} s ) | 12 |

191 | In an electron gun, the control grid is given negative potential, relative to cathode in order to A. accelerate the electrons B. decrease KE of electrons C. repel the electrons D. decelerate the electrons | 12 |

192 | A double ionized lithium atom is hydrogen-like with atomic number 3 (a) Find the wavelength of the radiation required to excite the electron in ( boldsymbol{L} boldsymbol{i}+ ) + from the first to the third Bohr orbit. (lonization energy of the hydrogen atom equals ( 13.6 e V lambda ) (b) How many spectral lines are observed in the emission spectrum of the above excited system? A . ( 114.7 A^{circ} ), Three lines. B. ( 113.7 A^{circ} ), four lines. c. ( 115.7 A^{circ} ), two lines. D. ( 116.7 A^{circ} ), one lines. | 12 |

193 | An electron is moving in an orbit of a hydrogen atom from which there can be a maximum of six transitions. An electron is moving in an orbit of another hydrogen atom from which there can be a maximum of three transitions. The ratio of the velocity of the electron in these two orbits is ( mathbf{A} cdot underline{5} ) B. ( frac{3}{4} ) ( c cdot frac{1}{2} ) D. | 12 |

194 | The angular momentum of electron is ( J ) Its magnetic moment will be A ( cdot frac{m J}{2 e} ) в. ( frac{e J}{2 m} ) c. ( frac{2 m}{e j} ) D. ( frac{e m j}{2} ) | 12 |

195 | The ratio of nuclear magneton and Bohr magneton is ( mathbf{A} cdot m_{e} / m_{p} ) в. ( m_{p} / m_{e} ) ( mathbf{c} cdot m_{e} m_{p} ) ( mathbf{D} cdot 2 m_{p} / m_{e z} ) | 12 |

196 | A proton and an ( alpha- ) particle are accelerated through the same potential The ratio of their velocities is A . 1: 2 B. 1: c. 1: D. ( sqrt{2}: 1 ) | 12 |

197 | An alpha nucleus of energy ( frac{1}{2} m v^{2} e V ) bombards a heavy nuclear target of charge ( Z e . ) Then the distance of closest approach for the alpha nucleus will be proportional to This question has multiple correct options A ( frac{1}{Z e} ) B ( cdot v^{2} ) c. ( frac{1}{m} ) D. ( frac{1}{v^{2}} ) | 12 |

198 | Particles and their anti-particles have A. Same masses but opposite spins B. Same masses but opposite magnetic moments C. Same masses and same magnetic moments D. Opposite spins and same magnetic moments | 12 |

199 | The voltage across the electrodes of a cathode ray tube is 500 V. Then the speed of the electron is A ( cdot 2.6 times 10^{7} m s^{-1} ) B. ( 1.33 times 10^{7} m s^{-1} ) ( mathbf{c} cdot 2.8 times 10^{7} m s^{-1} ) D. ( 1.9 times 10^{7} mathrm{ms}^{-1} ) | 12 |

200 | In a Geiger-Marsden experiment, calculate the distance of closest approach to the nucleus of ( Z=80 ) when ( alpha ) -particle of ( 8 M e V ) energy impinges on it before it comes momentarily to rest and reverses its direction. How will the distance of closest approach be affected when the kinetic energy of the ( alpha ) -particle is doubled? | 12 |

201 | Using Rutherford model of the atom, derive the expression for the total energy of the electron in hydrogen atom What is the significance of total negative energy possessed by the electron? OR Using Bohr’s postulates of the atomic model derive the expression for radius of nth electron orbit. Hence obtain the expression for Bohrs radius. | 12 |

202 | In X-ray spectrum, transition of an electron from an outer shell to an inner shell gives a characteristics X-ray spectral line. If we consider the spectral ( operatorname{lines} K_{beta}, L_{beta}, M_{alpha} ) then A. ( K_{beta} ) and ( L_{beta} ) have a common inner shell B. ( K_{beta} ) and ( L_{beta} ) have a common outer shell c. ( L_{beta} ) and ( M_{alpha} ) have a common outer shel 1 D. ( L_{beta} ) and ( M_{alpha} ) have a common inner shell | 12 |

203 | Gases exert pressure on the walls of the container, because the gas molecules A. Have finite volume B. Obey Boyle’s law c. Possess momentum D. collide with one another | 12 |

204 | The ratio ofthe radius of the orbit for the electron orbiting the hydrogen nucleus to that of an electron orbiting a deuterium nucleus is A . 1: B. 1: c. 2: D. 1:3 | 12 |

205 | The de-Broglie wavelength ( lambda_{n} ) of the electron in the nth orbit of hydrogen atom is A. Inversely proportional to ( n ) B. Proportional to ( n^{2} ) c. Proportional to ( n ) D. Inversely Proportional to ( n^{2} ) E. Inversely proportional to radius of the orbit in the nth state | 12 |

206 | The mass number ( A ) of an atom is equal to the A. Number of electrons B. Number of neutrons + electrons C. Number of protons + neutrons D. Number of protons + electrons | 12 |

207 | An electron in ( n ) th excited state in a hydrogen atom comes down to first excited state by emitting ten different wavelengths. Find the value of ( n ) (an integer) | 12 |

208 | Hydrogen atom in ground state takes up a photon of ( lambda=50 ) nm (uv light) Find the ( K E ) with which it is emitted. A . ( 14.4 e V ) B. ( 12.2 e V ) c. ( 13.6 e V ) D. ( 11.2 e V ) | 12 |

209 | An ( alpha ) – particle accelerated through volt is fired towards a nucleus. Its distance of closest approach is ( r ). If a proton is accelerated through the same potential and fired towards the same nucleus, the distance of closest approach of proton will be: ( A ) B . ( 2 r ) ( mathrm{c} cdot r / 2 ) D. ( r / 4 ) | 12 |

210 | What will be the ratio of the radii of two nuclei of mass numbers ( A_{1} ) and ( A_{2} ) ? | 12 |

211 | The angular momentum of an electron in an orbit is quantized because it is a necessary condition for the compatibility with A. Wave nature of electron B. Particle nature of electron c. Pauli’s exclusion behaviour D. None of these | 12 |

212 | Assertion In Rutherford’s gold foil experiment, very few ( alpha ) -particles are deflected back. Reason Nucleus present inside the atom is heavy. | 12 |

213 | the frequency of the first line in Lyman series in the hydrogen spectrum is ( V ) What is the frequency of the corresponding line in the spectrum of doubly ionized Lithium? | 12 |

214 | Using postulates of Bohr’s theory of hydrogen atom, show that the total energy of electron increases as ( frac{1}{n^{2}} ) where ( n ) is the principal quantum number of the atom | 12 |

215 | Gold is chosen by Rutherford for his ( alpha ) ray scattering experiment because: A. gold has high malleability B. gold has high ductility c. gold has high density D. gold is the least reactive element | 12 |

216 | The atoms of sample ( A ) after passing of light through it A. May be in the first excited state B. May be in the second excited state c. May be in both first and second excited states D. None of the above | 12 |

217 | Which of the following observations of ( alpha ) -ray scattering experiment lead to the presence of small positively charged nucleus in the centre? This question has multiple correct options A. Most of the ( alpha ) -particles passed straight B. Most of the ( alpha ) -particles rebounded after hitting the atoms c. only a few ( alpha ) -particles deflected away from their path D. Very few ( alpha ) -particles rebounded | 12 |

218 | The difference between ( (boldsymbol{n}+boldsymbol{2})^{t h} ) Bohr radius and ( n^{t h} ) Bohr radius is equal to the ( (n-2)^{t h} ) Bohr radius. The value of ( n ) is: | 12 |

219 | The ratio of the wavelength for ( 2 rightarrow 1 ) transition in ( L i^{+}, H e^{+} ) and ( H ) is : A .1: 2: 3 B. 1: 4: 9 c. 4: 9: 36 D. 3: 2: 1 | 12 |

220 | toppr Q Type your question decay products of the neutron. Therefore, considering the decay of a neutron as a two-body decay process, it was predicted theoretically that the kinetic energy of the electron should be a constant. But experimentally, it was observed that the electron kinetic energy has a continuous spectrum. Considering a three-body decay process, i.e. ( boldsymbol{n} rightarrow boldsymbol{p}+boldsymbol{e}^{-}+overline{boldsymbol{v}}_{e}, ) around 1930, Pauli explained the observed electron energy spectrum. Assuming the anti-neutrino ( left(bar{v}_{e}right) ) to be massless and possessing negligible energy, and the neutron to be at rest, momentum and energy conservation principles are applied. From this calculation, the maximum kinetic energy of the electron is ( 0.8 times 10^{6} e V . ) The kinetic energy carried by the proton is only the recoil energy. What is the maximum energy of the anti-neutrino? A. Zero B. Much less than ( 0.8 times 10^{6} e V ). C . Nearly ( 0.8 times 10^{6} mathrm{eV} ) D. Much larger than ( 0.8 times 10^{6} e V ) | 12 |

221 | According to Bohr’s model of the atom, atoms emit or absorb radiation only at certain wavelengths.ldentify why is it so A. Because the protons and electrons are distributed evenly throughout the atom B. Because electrons can orbit the nucleus at any radius c. Because electrons orbit the nucleus only at certain discrete radii D. Because protons orbit the nucleus only at certain discrete radii E. Because photons can only have discrete wavelength | 12 |

222 | Ruthen-ford used which of the following elements in his scattering experiment A. Gold B. Silver c. Alluminum D. Antimony | 12 |

223 | The energy of the em waves is of the order of 15 keV. To which part of the spectrum does it belong? A. ( gamma ) rays B. x rays c. Infra – red rays D. Ultraviolet rays | 12 |

224 | Imagine an atom made of a proton and a hypothetical particle of double the mass of the electron but having the same charge as the electron. Apply Bohr atom model and consider all possible transitions of this hypothetical particle to the first excited level. The longest wavelength photon that will be emitted has wavelength [Rydberg Constant = R] equal to A. ( frac{9}{5 R} ) в. ( frac{36}{5 R} ) c. ( frac{18}{5 R} ) D. ( frac{4}{R} ) | 12 |

225 | The diagram below shows a cathode ray tube in which the arrow indicates a beam of charged particles approaching an electric field between the plates ( A ) and B. Name the charged particles. A. Electron B. Proton c. Neutron D. Alpha | 12 |

226 | An ( alpha- ) particle passes through a potential difference of ( 2 times 10^{6} V ) and then it becomes incident on a silver foil. The charge number of silver is 47. The distance of closest approach of the particle to the nucleus will be: A. ( 6.4 times 10^{-13} mathrm{m} ) B. ( 4.3 times 10^{-13} mathrm{m} ) c. ( 2.1 times 10^{-13} m ) D. ( 3.76 times 10^{-15} mathrm{m} ) | 12 |

227 | The particle used by Rutherford in ( alpha ) -ray scattering experiment was A. neutron B. electron c. helium nuclei D. x rays | 12 |

228 | An alpha particle collides elastically with a stationary nucleus and continues moving at an angle of ( 60^{circ} ) with respect to the original direction of motion. The nucleus recoils at an angle of ( 30^{0} ) with respect to this direction Mass number of the nucleus is : A. 3 B. 4 ( c cdot 6 ) D. 8 | 12 |

229 | The clarification of discrete energy levels in atoms was first given experimentally by : A. Thomsons experiment B. Millikans oil drop experiment c. Frank – Hertz experiment D. Leonard experiment | 12 |

230 | Rutherford scattering experiment is related to the size of the A. Nucleons B. Electron c. Atom D. Nucleus | 12 |

231 | If the Rydberg constant for hydrogen atom is ( R, ) then the Rydberg constant for positronium atom is A ( .2 R ) в. ( R ) c. ( R / 2 ) D. ( 4 . R ) | 12 |

232 | The ground state energy of hydrogen atom is ( -13.6 e V ) (i) What is the kinetic energy of an electron in the ( 2^{n d} ) excited state? | 12 |

233 | The electron in a hydrogen atom makes a transition ( n_{1} rightarrow n_{2}, ) where ( n_{1} ) and ( n_{2} ) are the principal quantum numbers of the two states. Assume the Bohr model as valid in this case. The frequency of the orbital motion of the electron in the initial state is ( 1 / 27 ) of that in the final state. The possible values of ( n_{1} ) and ( n_{2} ) are A ( cdot n_{1}=6, n_{2}=3 ) в. ( n_{1}=4, n_{2}=2 ) c. ( n_{1}=8, n_{2}=1 ) D. ( n_{1}=3, n_{2}=1 ) | 12 |

234 | An electron is at ground state of the ( mathrm{H} ) atom. Minimum energy required to excite the ( H ) atom into second excited state is: A. 13.6 eV B. 12.1 eV c. 10.2 eV D. 3.4 eV | 12 |

235 | For absorption and emission spectra of atoms which one of the following particle changes energy levels? A. Alpha B. Electron c. Neutron D. Photon E. Proton | 12 |

236 | If velocity of ( alpha- ) particle is made ( 1 / 3 ) times, then ( % ) variation in distance of closest approach will be: (with respect to initial) A. 300% B. 600% c. ( 800 % ) D. 80% | 12 |

237 | Matching pairs in the two lists given below are ListList-II A) Gravitions E) Hyperons B) Baryons F) Positrons C) Pions G) Particles with zero mass nd with a spin of unity D) Leptons H) Decay to -mesons I) Massless particles with a probable spin of two units ( A cdot A-E, B-H, C-G, D-1 ) B. A-I,B-E,C-H,D-F c. ( A-H, B-F, C-1, D-E ) D. A-F,B-G,C-E,D-H | 12 |

238 | Radius of the second Bohr orbit of a singly ionised helium atom is A ( .0 .53 A^{circ} ) B . ( 1.06 A^{circ} ) c. ( 0.265 A^{circ} ) D. ( 0.132 A^{circ} ) | 12 |

239 | Wavelength of the first line of Balmer series is 600 n m. The wavelength of second line of the Balmer series will be: A. ( 444 n m ) B. ( 800 n m ) ( mathbf{c} .388 n m ) D. ( 632 n m ) | 12 |

240 | A tissue paper soaked with polluted water showed ( K_{alpha} ) peaks at ( 78.9 mathrm{pm}, 146 ) ( mathrm{pm}, 158 mathrm{pm} ) and ( 198 mathrm{pm} . ) Find the elements it contained. | 12 |

241 | (i) In a cathode ray tube what is the function of anode? (ii) State the energy conversion taking place in a cathode ray tube. (iii) Write one use of cathode ray tube. | 12 |

242 | The speed of sound in air is ( v . ) Both the source and observer are moving towards each other with equal speed ( u ) The speed of wind is ( w ) from source to observer. Then, the ratio ( left(frac{f}{f_{0}}right) ) of the apparent frequency to the actual frequency is given by A ( cdot frac{v+u}{v-u} ) в. ( frac{v+w+u}{v+w-u} ) c. ( frac{v+w+u}{v-w-u} ) D. ( frac{v-w+u}{v-w-u} ) | 12 |

243 | In a Rutherford scattering experiment when a projectile of charge ( Z_{1} ) and mass ( M_{1} ) approaches a target nucleus of charge ( Z_{2} ) and mass ( M_{2} ), the distance of closest approach is ( r_{0} . ) The energy of the projectile is : A . Directly proportional to mass ( M_{1} ) B. Directly proportional to ( M_{1} times M_{2} ) C. Directly proportional to ( Z_{1} Z_{2} ) D. Inversely proportional to ( Z_{1} ) | 12 |

244 | ( frac{k}{k} ) | 12 |

245 | Electrons of mass ( mathrm{m} ) and charge e are accelerated through a potential difference V and strike the target. The maximum speed of these electrons is A ( cdot frac{e V}{m} ) B. ( frac{e V^{2}}{m} ) c. ( sqrt{frac{e V}{m}} ) D. ( sqrt{frac{2 e V}{m}} ) | 12 |

246 | The mass number of ( H e ) is 4 and that for sulphur is ( 32 . ) The radius of sulphur nuclei is larger than that of helium by A. ( sqrt{8} ) B. 4 ( c cdot 2 ) D. 8 | 12 |

247 | An electron enters a parallel plate capacitor with horizontal speed ( mu ) and is found to deflect by angle ( theta ) on leaving the capacitor as shown. It is found that ( tan theta=0.4 ) and gravity is negligible. If the initial horizontal speed is doubled, then tan will be. A. 0.1 B. 0.2 c. 0.8 D. 1.6 | 12 |

248 | True or False Rutherford’s atomic model was successful in explaining stability of the atom | 12 |

249 | The first member of the Balmer series of hydrogen atom has wavelength of ( 6561 A ). The wavelength of the second member of the Balmer series (in ( n m ) ) is | 12 |

250 | a sodium lamp of power 10 W is emmiting phtons of wavelength 590 nm Assuming that ( 60 % ) of the consumed energy is converted into light, Find the number of photons emitted per second by the lamp. | 12 |

251 | Identify which of the following is the smallest discrete value of any quantity in physics? ( A cdot ) atom B. molecule. c. proton D. electron E . quantum | 12 |

252 | The approximate value of quantum number ‘ ( n^{prime} ) for the circular orbit of hydrogen of 0.0001 mm in diameter is A. 1000 B. 60 c. 10000 D. 31 | 12 |

253 | If ( left(frac{0.51 times 10^{-10}}{4}right) m, ) is the radius of smallest electron orbit in hydrogen like atom, then this atom is A. H-atom в. ( H e^{+} ) ( mathrm{c} cdot L i^{2} ) ( D cdot B e^{3} ) | 12 |

254 | n which transition is a Balmer series photon absorbed? ( A cdot I ) 3. II ( c_{1} ) D ( V ) | 12 |

255 | J.J.Thomson for the first time identified electron as a particle and his son G.P.Thomson first time identified electron as a wave and both were awarded Nobel Prize in different years. A. True B. False | 12 |

256 | If the ionization potential in the ground state for hydrogen is ( 13.6 e . V . ) then find the excitation potential of the third orbit. | 12 |

257 | The space between a proton and electron in hydrogen atom is : A. full of air B. full of ether c. full of electromagnetic radiations D. empty | 12 |

258 | When there occurs a transition from ( boldsymbol{n}=mathbf{3} ) to ( boldsymbol{n}=mathbf{2} ) state in the hydrogen the atom recoils. If ( boldsymbol{E}_{1}-boldsymbol{E}_{2}=mathbf{1} . mathbf{9} e boldsymbol{V} ) then the ratio of ( K E ) of recoil and the photon energy is of the order of A . 10 B . ( 10^{-9} ) ( mathrm{c} cdot 10^{-6} ) D. ( 10^{-11} ) | 12 |

259 | Find the shortest wavelength in Paschen series if, the longest wavelength in Balmer series is ( 6563 A^{0} ) | 12 |

260 | The electron in a hydrogen atom makes a transition ( n_{1} rightarrow n_{2} ) whose ( n_{1} ) and ( n_{2} ) are the principal quantum numbers of the two states. Assume the Bohr model to be valid. The frequency of orbital motion of the electron in the initial state is ( 1 / 27 ) of that in the final state. The possible value of ( n_{1} ) and ( n_{2} ) are ( mathbf{A} cdot n_{1}=4, n_{2}=2 ) B ( . n_{1}=3, n_{2}=1 ) ( mathbf{c} cdot n_{1}=8, n_{2}=1 ) ( mathbf{D} cdot n_{1}=6, n_{2}=3 ) | 12 |

261 | The size of the nucleus is approximately: A ( cdot 10^{-18} mathrm{m} ) B . ( 10^{-10} mathrm{m} ) ( c cdot 10^{-8} mathrm{m} ) D. none of these | 12 |

262 | In the Bohr model of a hydrogen atom, the centripetal force is furnished by the coulomb attraction between the proton and the electron. If ( a_{0} ) is the radius of the ground state orbit, ( m ) is the mass and ( e ) is the charge on the election and ( varepsilon_{0} ) is the vacuum permittivity, the speed of the electron is? A. 0 B. ( frac{e}{sqrt{varepsilon_{0} a_{0} m}} ) c. ( frac{e}{sqrt{4 pi varepsilon_{0} a_{0} m}} ) D. ( sqrt{frac{4 pi varepsilon_{0} a_{0} m}{e}} ) | 12 |

263 | Find out the wavelength of the electron orbiting in the ground state of hydrogen atom | 12 |

264 | Which of the following samples will have the same number of atoms as 40 g calcium? A. 24 g magnesium B. 64 g silphur c. 14 g nitrogen D. 8 g oxygen | 12 |

265 | In terms of Bohr radius ( a_{0}, ) the radius of the second Bohr orbit of a hydrogen atom is given by: ( A cdot 8 a_{0} ) в. ( 4 a_{0} ) ( c cdot 2 a_{0} ) D. ( sqrt{2} a_{0} ) | 12 |

266 | With what velocity should an ( alpha ) -particle travel (expressed in ( n times 10^{6} m s e c^{-1} ) take the value of ( n ) to the nearest integer) towards the nucleus of a copper atom so as to arrive at a distance ( 10^{-13} ) metre from the nucleus of the copper atom? | 12 |

267 | Cathode rays are deflected towards A. positive electrode B. negative electrode c. both electrode D. none of these | 12 |

268 | Which of the following is not a drawback of Ruther-ford atomic model? A. It failed to explain why electrons just simply fall into the nucleus. B. It failed to explain why an atom emits discratt spectrum. C. It failed to explain why only a very small amount of ( alpha ) paticles get scattered D. none of these | 12 |

269 | When a hydrogen atom emits a photon in going from ( n=5 ) to ( n=1 ), its recoil speed is almost ( mathbf{A} cdot 10^{-4} m / s ) B . ( 2 times 10^{-2} mathrm{m} / mathrm{s} ) c. ( 4 m / s ) D. ( 8 times 10^{-2} mathrm{m} / mathrm{s} ) | 12 |

270 | Explain the different types of spectral series in a hydrogen atom. | 12 |

271 | Explain the significance of quantum number? | 12 |

272 | The angular momentum of an electron in the first orbit of an ( L i^{+} ) ion is A ( cdot frac{3 h}{2 pi} ) в. ( frac{9 h}{2 pi} ) c. ( frac{h}{2 pi} ) D. ( frac{h}{6 pi} ) | 12 |

273 | Radiation of ( lambda=155 ) nm was irradiated to ( L i text { (work function }=5 e v) ) plate. The stopping potential. | 12 |

274 | An electron makes transition from ( boldsymbol{n}= ) ( mathbf{3}, boldsymbol{n}=mathbf{1} ) state in a hydrogen atom. The different possible number of photons that can be emitted is : ( mathbf{A} cdot mathbf{1} ) B . 2 ( c cdot 3 ) D. 6 | 12 |

275 | The ionisation energy of a hydrogen like Bohr atom is 4 Rydberg. What is the wavelength of the radiation emitted when the electronjumps from the first excited state to the ground state? | 12 |

276 | According to Bohr’s model, the minimum energy (in eV) required to remove an electron from the ground state of doubly ionised Li atom ( (z=3) ) is A . 40.8 B. 13.6 c. 122.4 D. 1.5 | 12 |

277 | If the transition of electron takes place from ( n=4 ) state, then the maximum number of spectral lines obtained for transition to ground state will be A. 6 B. 12 c. 18 D. 24 | 12 |

278 | The approximate value of quantum number ( n ) for the circular orbit of hydrogen 0.0001 mm diameter is A. 1000 B. 60 c. 10000 D. 31 | 12 |

279 | The cathode ray particles originates in a discharge tube from the A. Cathode B. Anode c. source of high voltage D. Residual gas | 12 |

280 | An electron in a hydrogen atom makes a transition from ( n=n_{1} ) to ( n=n_{2} . ) The time period of the electron in the initial state is eight times that in the final state. The possible values of ( n_{1} ) and ( n_{2} ) are This question has multiple correct options ( mathbf{A} cdot n_{1}=4, n_{2}=2 ) B ( . n_{1}=8, n_{2}=2 ) c. ( n_{1}=8, n_{2}=1 ) D ( cdot n_{1}=6, n_{2}=3 ) | 12 |

281 | Continuous spectrum is produced by This question has multiple correct options A. Incandescent electric bulb B. Sun C . Hydrogen molecules D. Sodium vapor lamp | 12 |

282 | In the study of Geiger-Marsdon experiment on scattering of ( boldsymbol{alpha} ) particles by a this foil of gold, draw the trajectory of ( boldsymbol{alpha}- ) particles in the coulomb field of target nucleus. Explain briefly how one gets the information on the size of the nucleus from this study: From the relation ( boldsymbol{R}=boldsymbol{R}_{0} boldsymbol{A}^{1 / 3}, ) where ( boldsymbol{R}_{0} ) is constant and ( A ) is the mass number of the nucleus, show that nuclear matter density is independently of ( A ) | 12 |

283 | The radius of a shell for ( boldsymbol{H}- ) atom is ( 4.761 A ). The value of ( n ) is: ( A cdot 3 ) B. 9 ( c cdot 5 ) D. None of these | 12 |

284 | How many times does the electron go round the first Bohr orbit of hydrogen atoms in 1 s? (in peta Hz) | 12 |

285 | Beta particles are essentially: A. neutrons B. protons c. electrons D. helium nuclei | 12 |

286 | If elements of quantum number greater than ‘ ( n^{prime} ) were not allowed, the number of possible elements in nature would have been A ( cdot frac{1}{2} n(n+1) ) ( ^{mathbf{B}}left{frac{n(n+1)}{2}right}^{2} ) c. ( frac{1}{6} n(n+1)(2 n+1) ) D. ( frac{1}{3} n(n+1)(2 n+1) ) | 12 |

287 | Write the Rutherford – Soddi law of ratio active decay and draw decay curve. | 12 |

288 | If ( n_{r} ) and ( n_{b} ) are the number of photons of red and blue lights respectively with same energy, then A ( cdot n_{r}>n_{b} ) в. ( n_{r}<n_{b} ) ( mathbf{c} cdot n_{r}=n_{b} ) D. no relation between ( n_{r} ) and ( n_{b} ) | 12 |

289 | An electron is in an excited state in a hydrogen like atom. It has a total energy of ( -3.4 e V . ) The kinetic energy of the electron is ( boldsymbol{E} ) and its de Broglie wavelength is ( lambda ) A ( . E=6.8 mathrm{eV}, lambda=-6.6 times 10^{-10} mathrm{m} ) B . ( E=3.4 mathrm{eV}, lambda=-6.6 times 10^{-10} mathrm{m} ) C . ( E=3.4 mathrm{eV}, lambda=-6.6 times 10^{-11} mathrm{m} ) D. ( E=6.8 e V, lambda=-6.6 times 10^{-11} mathrm{m} ) | 12 |

290 | An alpha nucleus of energy ( overline{2} ) mv bombards a heavy nuclear target of charge Ze. Then the distance of closest approach for the alpha nucleus will be proportional to ( ^{mathrm{A}} cdot frac{1}{mathrm{Z}} ) B ( cdot mathrm{v}^{2} ) c. ( frac{1}{mathrm{m}} ) D. ( frac{1}{v^{4}} ) | 12 |

291 | What is the mass of neutron? A ( cdot 1.675 times 10^{-24} g ) В. ( 9.1 times 10^{-31} k g ) c. ( 1.675 times 10^{-30} g ) D. ( 9.1 times 10^{-27} k g ) | 12 |

292 | Draw the diagram representing the schematic arrangement of the GeigerMarsdon experimental setup tor the alpha particle scattering. | 12 |

293 | The radius of an atom is of the order of: A ( cdot 10^{-10} mathrm{cm} ) B . ( 10^{-13} mathrm{cm} ) ( c cdot 10^{-15} mathrm{cm} ) ( D cdot 10^{-8} mathrm{cm} ) | 12 |

294 | The Interaction energy between an electron and proton is very small when they are far apart. A. True B. False | 12 |

295 | Assertion The plot of atomic number ( (y text { -axis) } v s ) number of neutrons ( (x- ) axis ) for stable nuclei shows a curvature towards ( x- ) axis from the line of ( 45^{circ} ) slope as the atomic number is increased. Reason Proton-proton electrostatic repulsion begins to overcome attractive forces involving proton and neutrons in heavier nucleides. A. ( S ) is correct but ( E ) is wrong B. ( S ) is wrong but ( E ) is correct c. Both ( S ) and ( E ) are correct and ( E ) is correct explanation of ( S ) D. Both ( S ) and ( E ) are correct but ( E ) is not correct explanation of ( S ) | 12 |

296 | The target used in a Coolidge tube for the production of ( X ) -rays is made up of A. manganese B. molybdenumm c. uranium D. radium | 12 |

297 | Alpha particles that come closer to the nuclei A. are deflected more B. are deflected less c. make more collision D. are slowed down more | 12 |

298 | A stream of electrons enters an electric field normal to the lines of force with a velocity of ( 3 times 10^{7} m / s . ) The electric intensity is ( 1800 mathrm{V} / mathrm{m} ). While traveling through a distance of ( 10 mathrm{cm}, ) the electron beam is deflected by ( 2 mathrm{mm} ) Then e/m in coulomb per kg will be A ( cdot 2 times 10^{-11} ) в. ( 2 times 10^{7} ) ( c cdot 2 times 10^{11} ) D. ( 2 times 10^{14} ) | 12 |

299 | The total energy of the electron in the hydrogen atom in the ground state is ( -13.6 mathrm{eV} . ) Which of the following is its kinetic energy in the first excited state? A . 13.6 ev B. 6.8 ev c. 3.4 ev D. ( 1.825 mathrm{eV} ) | 12 |

300 | Which of the following is true? A. Lyman series is a continuous spectrum B. Paschen series is a line spectrum in the infrared C. Balmer series is a line spectrum in the ultraviolet D. The spectral series formula can be derived from the Rutherford model of the hydrogen atom | 12 |

301 | The minimum orbital angular momentum of the electron in a hydrogen atom is ( A cdot h ) B. ( h / 2 ) ( c cdot h / 2 pi ) D. ( h / 2 lambda ) | 12 |

302 | The emission spectra of Sample ( boldsymbol{A} ) A. Must have 3 lines B. Must have 2 lines c. Must have 4 lines D. It is not formed | 12 |

303 | The acceleration of an electron in the first orbit of the hydrogen atom ( (boldsymbol{n}=mathbf{1}) ) is : A ( cdot frac{h^{2}}{pi^{2} m^{2} r^{3}} ) B. ( frac{h^{2}}{8 pi^{2} m^{2} r^{3}} ) c. ( frac{h^{2}}{4 pi m^{2} r^{3}} ) D. ( frac{2 pi^{2} k m e^{2} Z}{eta h} ) | 12 |

304 | Imagine an atom made up of proton and a a hypothetical particle of double the mass of the electron but having the same charge as the electron. Apply the Bohr atom model and consider all possible transitions of this hypothetical particle to the first excited level. The longest wavelength photon that will be emitted has wavelength ( lambda ) (give in term of the Rydberg constant R for the hydrogen atom) equal to ( A cdot 9 / 5 R ) B. 36/5 R c. ( 18 / 5 ) R D. 4/ R | 12 |

305 | The scientist who is credited with the discovery of ‘nucleus’ in an atom is A. Niels Bohr B. Ruther ford c. J.J. Thomson D. Balmer | 12 |

306 | How did Rutherford conclude that ( alpha ) particles were not deflected by the attraction of electrons inside the atom? | 12 |

307 | Rutherford’s experiment for the first time proved that atom has: A. Protons B. Nucleus c. Neutrons D. Electrons | 12 |

308 | Which of the following while in motion cannot be deflected by a magnetic field? A. Protons B. Cathode rays c. Alpha particles D. Neutrons | 12 |

309 | Most of the ( alpha ) -particles passed straight through the gold foil. This proved the existence of ( _{-} ) in an atom. A. electrons B. nucleus c. Empty space D. positive charge | 12 |

310 | Radius of first Bohr orbit is ( r . ) The radius of 2nd Bohr orbit is ( A cdot 8 r ) B. ( 2 r ) ( c cdot 4 r ) D. ( 2 sqrt{2} r ) | 12 |

311 | Name the three constituent of an atom and state their mass and charge of each. How are they distributed in an atom? | 12 |

312 | Assertion Nuclear fusion are made at very high temperature, ( boldsymbol{i} boldsymbol{e}_{bullet}, boldsymbol{1} boldsymbol{0}^{boldsymbol{7}} boldsymbol{K} ) Reason Nuclear fusion reactions are exoergic. ( mathbf{A} cdot S ) is correct but ( E ) is wrong B. ( S ) is wrong but ( E ) is correct C. Both ( S ) and ( E ) are correct and ( E ) is correct explanation of ( S ) D. Both ( S ) and ( E ) are correct but ( E ) is not correct explanation of ( S ) | 12 |

313 | An electron with kinetic energy ( boldsymbol{E} boldsymbol{e} boldsymbol{V} ) collides with a hydrogen atom in the ground state. The collision will be elastic A. for all values of ( E ) B. for ( E<10.2 e V ) c. for ( E<13.6 e V ) D. only for ( E<3.4 e V ) | 12 |

314 | According to Bohr, ‘Angular momentum of an orbiting electron is quantised’ What is meant by this statement? | 12 |

315 | The Bohr radius of the fifth electron of phosphorus (atomic number = 15) acting as dopant in silicon (relative dielectric constant ( =12 ) ) is A ( cdot 10.6 ~ A^{circ} ) B. 0.53 ( A^{0} ) c. ( 21.2 A^{circ} ) D. None of these | 12 |

316 | The kinetic energy of an electron in the first Bhor orbit of hydrogen is : A. 13.6 eV B. 6.8 eV c. ( -13.6 e V ) D. 27 eV | 12 |

317 | The nucleus of tritium consist of A. 1 proton + 1 neutron B. 1 proton + 3 neutron c. 1 proton ( + ) zero neutrons D. 1 proton +2 neutrons | 12 |

318 | The terminology of different parts of the electromagnetic spectrum is given in the text. Use the formula ( boldsymbol{E}=boldsymbol{h v} ) (for energy of a quantum of radiation photon) and obtain the photon energy in units of ( e V ) for different parts of the electromagnetic spectrum. In what ways are the different scales of photon energies that you obtain related to the sources of electromagnetic radiation.? | 12 |

319 | If a cathode ray tube has a potentia difference ( V ) volt between the cathode and anode, then the speed ( v ) of cathode rays is given by: A ( cdot v propto V^{2} ) В. ( v propto sqrt{V} ) ( ^{mathrm{c}} cdot_{v} propto frac{1}{V} ) D. ( v propto V ) | 12 |

320 | Stability of an atom was successfully explained by Rutherford’s atomic model A. True B. False | 12 |

321 | Write the different types of Hydrogen Spectral series. The Lyman series of Hydrogen spectrum lies in the ultraviolet region. Why? | 12 |

322 | A Bohr hydrogen atom undergoes a transition ( n=5 ) to ( n=4 ) and emits a photon of frequency ( f ). Frequency of circular motion of electron in ( boldsymbol{n}=boldsymbol{4} ) orbit is ( f_{4} . ) The ratio ( f / f_{4} ) is found to be 18/5m. State the value of ( m ) | 12 |

323 | Name three constituents of an atom and state mass and charge of each. | 12 |

324 | When electron remains between orbits, its momentum is : A. quantized B. dequantized c. emitted D. changed always | 12 |

325 | Match the following: List – 1 List – 2 a) Burning candle e) line spectrum f) continuous b) Sodium vapour ( quad ) spectrum c) Bunsen flame g) bond spectrum g) Dark lines in solar h) Absorption spectrum ( quad ) spectrum ( A cdot a-g, b-e, c-f, d-h ) B. ( a-g, b-f, c-e, d-h ) C. ( a-f, b-g, c-e, d-h ) D. ( a-f, b-e, c-g, d-h ) | 12 |

326 | If ( n ) is the orbit number of the electron in a hydrogen atom, the correct statement among the following is A. Electron energy increases as ( n ) increases B. Hydrogen emits infrared rays for the electron transition from ( n=infty ) to ( n=1 ) C. Electron energy is zero for ( n=1 ) D. Electron energy varies as ( n^{2} ) | 12 |

327 | In the case of the Bohr atomic model if ( E_{K} ) and ( U ) are the kinetic and potential energies of an electron in an orbit then: ( mathbf{A} cdot E_{K}+U=0 ) B . ( E_{K}-U=0 ) ( mathbf{c} cdot 2 E_{K}+U=0 ) D. ( E_{K}+2 U=0 ) | 12 |

328 | A metal M of equivalent mass E forms an oxide of molecular formula ( M_{x} O_{v} ) The atomic mass of the metal is given by the correct equation. ( A cdot 2 E(y / x) ) B. xyE ( c cdot E / y ) D. y/E E. E/2 (x/y) | 12 |

329 | Name spectral series of hydrogen which lies in the ultraviolet region of electromagnetic spectrum | 12 |

330 | The main defect of Bohr’s atom model is A. mixing of classical and quantum theories B. exclusion of nuclear motion c. failed to explain the fine structure of spectral lines D. failed to explain larger atoms | 12 |

331 | As one considers orbits with higher values of ( n ) in a hydrogen atom, the electric potential energy of the atom A . decreases B. increases c. remains the same D. does not increase | 12 |

332 | What is the purpose of filament in electron gun inside a cathode ray tube? A. To support the cathode B. To protect the cathode c. To cool the cathode D. To heat the cathode | 12 |

333 | When the sun is directly overhead, the surface of the earth receives ( 1.4 times ) ( 10^{3} W m^{-2} ) of sunlight. Assume that the light is monochromatic with average wavelength ( 500 n m ) and that no light is absorbed in between the sun and the earth’s surface. The distance between the sun and the earth is ( 1.5 times 10^{11} m ) (a) Calculate the number of photons falling per second on each square metre of earth’s surface directly below the sun (b) How many photons are there in each cubic metre near the earth’s surface at any instant? (c) How many photons does the sun emit per second? | 12 |

334 | The energy (in ( e V ) ) required to excite an electron from ( n=2 ) to ( n=4 ) state in hydrogen atom ( mathbf{A} cdot+2.55 ) в. -3.4 c. +4.25 D. -0.85 | 12 |

335 | The ionization energy for excited hydrogen atom in eV will be A . 13.6 B. less than 13.6 c. greater than 13.6 D. 3.4 or less | 12 |

336 | If ( lambda ) is the wavelength of hydrogen atom from the transition ( n=3 ) to ( n=1 ), then what is the wavelength for doubly ionised lithium ion for same transition? ( A cdot frac{lambda}{3} ) B. ( 3 lambda ) ( c cdot frac{lambda}{9} ) D. ( 9 lambda ) | 12 |

337 | The best evidence that electrons are arranged in definite orbits or energy levels is based on the observation that: A. atomic spectra consist of discrete lines and not continuous bands B. electrons in the beta ray have high kinetic energy c. the penetrating power of cathode ray electrons depends upon the voltage used to produce them D. electrons revolve around the nucleus | 12 |

338 | The particle that possesses half integral spin is A. Photon B. Pion c. Proton D. K-meson | 12 |

339 | Which of the following particles cannot be deflected by magnetic field? A. Electrons B. Neutrons c. ( alpha ) – particles D. Protons | 12 |

340 | A student measures the level of radiation emitted by a radioactive sample. The table shows the readings she | 12 |

341 | Cathode ray tube is operating at ( 5 mathrm{kV} ) Then,what is the K.E. acquired by the electrons? A. 5 ev B. 5 MeV c. ( 5 mathrm{keV} ) ( D .5 v ) | 12 |

342 | In Thomson mass spectrograph ( mathrm{E} perp overrightarrow{mathrm{B}} ) then the velocity of undeflected electron beam will be :- A ( cdot frac{|vec{E}|}{|vec{B}|} ) B. ( overrightarrow{mathrm{E}} times overrightarrow{mathrm{B}} ) ( ^{mathbf{C}} cdot frac{|vec{B}|}{|vec{E}|} ) D. ( frac{E^{2}}{B^{2}} ) | 12 |

343 | The diagram below shows a cathode ray tube in which the arrow indicates a beam of charged particles approaching an electric field between the plates ( A ) and B. Name the charged particles. A. Electron B. Proton c. Neutron D. Alpha | 12 |

344 | The angular momentum of electron in ( n^{t h} ) orbit is given by ( A cdot n h ) в. ( frac{h}{2 pi n} ) c. ( n frac{h}{2 pi} ) D. ( n^{2} frac{h}{2 pi} ) | 12 |

345 | In 1911, the physicist Emest Rutherford discovered that atoms have a tiny, dense nucleus by shooting positively charged particles at a very thin gold foil A key physical property which led Rutherford to use gold that it was. A. Electrically conducting B. Highly malleable c. shiny D. None-reactive | 12 |

346 | Describe the JJ. Thomson method for determining the specific charge of an electron. | 12 |

347 | For a neutral atom, the first ionization energy is equal to its electron affinity. A. True B. False | 12 |

348 | Electrons of energies ( 10.20 e V ) and ( 12.09 e V ) can cause radiation to be emitted from hydrogen atoms. Calculate, in each case, the principal quantum of the orbit to which electron in the hydrogen atom is raised and the wavelength of the radiation emitted if it drops back to the ground state. Find the sum of these numbers. | 12 |

349 | When a vapour is excited at low pressure by passing an electric current through it, a spectrum is obtained. a) Draw a spectral series of emission lines in hydrogen. b) Name the different series of hydrogen atom c) In which region Lyman series is located. | 12 |

350 | In a cathode ray tube, why is the filament made of tungsten? | 12 |

351 | An element ( X ) has number of protons ( =4 ) What will be its mass number if it has 3 neutrons? ( A cdot 4 ) B. 3 c. 7 D. 5 | 12 |

352 | Monochromatic radiations of wavelength ( lambda ) are incident on a hydrogen sample in the ground state. Hydrogen atom absorbs the light and subsequently emits radiations of 10 different wavelengths. The value of ( lambda ) is nearly A . 203 nm B. 95 nm c. ( 80 n m ) D. 73 nm | 12 |

353 | Rutherford’s alpha particle scattering experiment eventually led to the conclusion that: A. mass and energy are related B. electrons occupy space around the nucleus c. neutrons are buried deep in the nucleus D. the point of impact with matter can be precisely determined | 12 |

354 | 21. An alpha nucleus of energy (1/2) my bombards a heavy nuclei target of charge Ze. Then the distance of closest approach for the alpha nucleus will be proportional to (c) v² (a) m (AIEEE 2006) | 12 |

355 | There are seven orbitals in a subshell then the value of ( l ) for it will be A ( . l=4 ) в. ( l=3 ) c. ( l=2 ) D. ( l=1 ) | 12 |

356 | The electron in the hydrogen atom is moving with a speed of ( 2.3 times 10^{6} m / s ) in an orbit of radius 0.53 A. Calculate the period of revolution of electron. ( (pi= ) 3.142 | 12 |

357 | The wave length of K-ray line of an anti cathode element of atomic number ( Z ) is nearly proportional to: ( A cdot Z^{2} ) B . ( (Z-1)^{2} ) c. ( 1 /(z-1) ) D. ( 1 /(Z-1)^{2} ) | 12 |

358 | Assertion The mass of a nucleus can be either less than or more than the sum of the masses of nucleons present in it. Reason The whole mass of the atom is concentrated in the nucleus. A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion c. Assertion is correct but Reason is incorrect D. Both Assertion and Reason are incorrect | 12 |

359 | The electron is present in the -1.51 eV energy state. Find the angular momentum of the electron. A. ( frac{h}{pi} ) в. ( frac{h}{2 pi} ) c. ( frac{3 h}{2 pi} ) D. ( frac{2 h}{pi} ) E. none of these | 12 |

360 | If the cathode and the anode are kept at the same potential, the emitted electrons have A. the maximum KE equal to 1.36 ev B. the average KE equal to (1.36/2) ev c. the maximum KE depends upon the material D. none of the above | 12 |

361 | In which of the following fields cathode rays show minimum deflection? A. Electric field B. Magnetic field c. Plasma field D. Gravitational field | 12 |

362 | Q Type your question (a) The size of the atom in the Thomsons model is ( dots-m ) atomic size in Rutherford’s model. (much greater than/no different from/much less than.) (b) In the ground state of ……….. electrons are in stable equilibrium, while in electrons always experience a net force. (Thomsons model/ Rutherfords model.) (c) A classical atom based on ( ldots ). is doomed to collapse. (Thomsons model/ Rutherfords model.) (d) An atom has a nearly continuous mass distribution in ( a )……….. but has a highly non-uniform mass distribution in (Thomsons model/ Rutherfords model.) (e) The positively charged part of the atom possesses most of the mass in (Rutherfords model / both the models.) | 12 |

363 | The force experienced by the cathode rays when they pass through a uniform electric field of intensity ( bar{E} ) is: A. in the direction of the electric field B. in the direction opposite to that of the electric field c. at right angles to the electric field D. zero, because cathode rays do not have any charge | 12 |

364 | In scattering experiment, find the distance of closest approach, if a ( 6 mathrm{MeV} ) ( alpha ) -particle is used A . ( 3.2 times 10^{-16} mathrm{m} ) В. ( 2 times 10^{-14} mathrm{m} ) c. ( 4.6 times 10^{-15} mathrm{m} ) D. ( 3.2 times 10^{-15} mathrm{m} ) | 12 |

365 | To which of the following the angular velocity of the electron in the n-th Bohr orbit is proportional? ( mathbf{A} cdot n^{2} ) в. ( frac{1}{n^{2}} ) c. ( frac{1}{n^{frac{3}{2}}} ) D. ( frac{1}{n^{3}} ) | 12 |

366 | If radius of the ( _{13}^{27} A l ) nucleus is estimated to be 3.6 fermi, then the radius of ( frac{125}{52} ) Te nucleus be nearly. A. 6 fermi B. 8 fermi c. 4 fermi D. 5 fermi | 12 |

367 | An electron with energy 12.09 eV strikes hydrogen atom in ground state and gives its all energy to the hydrogen atom. Therefore hydrogen atom is excited to A. Fourth B. Third c. second D. First | 12 |

368 | A nucleus ( X^{235} ) splits into two nuclei having the mass numbers in the ratio ( 2: 1 . ) The ratio of the radii of those two nuclei is: A .2: 1 B. 1: 2 c. ( 2^{1 / 3}: 1 ) D. ( 1: 2^{1 / 3} ) | 12 |

369 | Among the following, is unstable in free space. A. Electron B. Proton c. Neutron D. ( alpha ) -particle | 12 |

370 | For the Paschen series the values of ( n_{1} ) and ( n_{2} ) in the expression ( Delta E= ) ( boldsymbol{R h c}left(frac{1}{boldsymbol{n}_{1}^{2}}-frac{1}{boldsymbol{n}_{2}^{2}}right) ) are ( mathbf{A} cdot n_{1}=1, n_{2}=2,3,4, ldots ) B ( cdot n_{1}=2, n_{2}=3,4,5, ldots ) c ( cdot n_{1}=3, n_{2}=4,5,6, dots ) D. ( n_{1}=4, n_{2}=5,6,7, ldots ) | 12 |

371 | The value of ( z ) is A. 5 B. 4 ( c .3 ) D. 2 | 12 |

372 | Check the wrong statement: A. Line spectrum is characteristic of the element B. Absorption line spectrum is characteristic of the element C. Continuous spectrum is characteristic of the source of light D. There are two prominent yellow lines in the spectrum of sodium | 12 |

373 | If ( u ) denotes 1 atomic mass unit. One atom of an element has mass exactly equal to ( A u, ) where ( A ) is mass number of element. ( mathbf{A} cdot A=1 ) B. ( A=12 ) c. ( A=16 ) D. ( A ) can take up any integral value from 1 to 110 | 12 |

374 | An electron collides with a Hydrogen atom in its ground state and excites it to ( n=3 ) state. The energy given to the Hydrogen atom in his inelastic collision (neglecting the recoil of Hydrogen atom) is A . ( 10.2 e V ) в. ( 12.1 e V ) c. ( 12.5 e V ) D. ( 13.6 e V ) | 12 |

375 | Which of the following products in a hydrogen atom are independent of the principal quantum number ‘ ( n ) ‘? The symbols have their usual meanings. This question has multiple correct options A . ( v n ) в. ( E r ) ( c . E n ) D. ( v r ) | 12 |

376 | If the average life time of an excited state of hydrogen is of the order of ( 10^{-8} s, ) estimate how many orbits an electron makes when it is in the state ( n=2 ) before it suffers a transition to state ( n=2left(text { Bohr radius } a_{0}=5.3 timesright. ) ( left.10^{-11} mright) ? ) | 12 |

377 | The energy levels of an atom are as shown here. Which of them will result in the transition of a photon of wavelength ( 275 n m ? ) which of this transitions corresponds to emissions of radiations of (1)maximum (11)Minimum | 12 |

378 | How many spectral lines are observed in spectra of ( boldsymbol{H} boldsymbol{e}^{+} ) ion? A .2 B. 4 ( c cdot 6 ) D. | 12 |

379 | What will be the velocity of the electron when it just reaches the positive plate? A ( cdot sqrt{frac{2 V e d}{m}} ) в. ( sqrt{frac{2 V e}{m}} ) c. ( sqrt{frac{2 V e}{m d}} ) D. ( sqrt{frac{V e d}{m}} ) | 12 |

380 | The angular momentum of the ( alpha- ) particles which are scattered through large angles by the heavier nuclei, is conserved because A. of the nature of repulsive forces B. the kinetic energy is conserved c. the potential energy is conserved D. there is no external torque | 12 |

381 | In Rutherford’s experiment, generally the thin foil of heavy atoms like gold, platinum etc. have been used to be bombarded by the ( alpha ) -particles. If the thin foil of light atoms like aluminium etc. is used, what difference would be observed from the above results? | 12 |

382 | How an atom becomes a negative ion, if: A. a proton leaves the atom B. an electron joins the atom c. an electron leaves the atom D. a protonjoins the atom E. a proton and an electron leave the atom | 12 |

383 | An electron tube was sealed off during manufacture at a pressure of ( 1.2 times ) ( 10^{-7} mathrm{mm} ) of mercury at ( 27^{circ} mathrm{C} ). Its volume is ( 100 mathrm{cm}^{3} . ) The number of molecules that remain in the tube is A ( .2 times 10^{16} ) В . ( 3 times 10^{15} ) c. ( 3.86 times 10^{11} ) D. ( 5 times 10^{11} ) | 12 |

384 | As the electron in the Bohr Orbit of hydrogen atom passes from state ( boldsymbol{n}=mathbf{2} ) to ( n=1, ) the ( K E(K) ) and ( P E(U) ) change as A. ( K ) two-fold, ( U ) also two-fold B. ( K ) four-fold, ( U ) also four-fold c. ( K ) four-fold, ( U ) two-fold D. ( K ) two-fold, ( U ) four-fold | 12 |

385 | For the transition from ( boldsymbol{n}=mathbf{2} rightarrow boldsymbol{n}=mathbf{1} ) which of the following will produce shortest wavelength? A. H atom B. D atom ( mathbf{c} cdot H e^{+} i o n ) D. ( L i^{2+} ) ion | 12 |

386 | What should retarding potential difference be applied between electrodes of the photocell for the photocurrent to drop to zero? A. ( 1.5 V ) в. ( 2.0 V ) c. ( 1.8 V ) D. 2.3V | 12 |

387 | The energy of the electron of the hydrogen atom in the ( n ) th orbit is ( E_{n}= ) ( -frac{13.6}{n^{2}} e V . ) Draw the energy level diagram for the hydrogen atom and show transitions corresponding to lives of Lyman and Balmer series. | 12 |

388 | In in nature there may not be an element for which the principal quantum number ( n>4 ), then the total possible number of elements will be A . 60 B. 32 ( c cdot 4 ) ( D cdot 64 ) | 12 |

389 | Rutherford’s alpha ( ( alpha ) ) particle scattering experiment resulted in discovery of: A . electron B. proton c. nucleus in the atom D. atomic mass | 12 |

390 | The conditions for the discharge of electricity in a discharge tube are : A. high temperature and high potential B. low pressure and high potential c. low pressure and high temperature D. low potential and high pressure | 12 |

391 | Magnetic field at the center (at nucleus) of the hydrogen-like atoms (atomic number ( =Z ) ) due to the motion of electron in ( n^{t h} ) orbit is proportional to A ( cdot frac{n^{3}}{z^{5}} ) B. ( frac{n^{4}}{z} ) c. ( frac{z^{2}}{n^{3}} ) D. ( frac{z^{3}}{n^{5}} ) | 12 |

392 | Alpha particles are projected towards fixed at a nucleus. Which of the paths shown in figure, is not possible ( A ) B. ( c ) ( D ) | 12 |

393 | Line spectrum contains information about the : A. Atoms of the prism B. Atoms of the source c. Molecules of the source D. Atoms as well as molecules of the source | 12 |

394 | How may sub-atomic particles are present in an a-particles used in Rutherford’s scattering experiment? A. No. of Protons – 4 No. of Neutrons – 0, No. of Electrons – 0 B. No. of Protons – 2. No. of Neutrons – 0, No. of Electrons – 2 c. No. of Protons – 2 , No. of Neutrons – 2, No. of Electrons – 0 D. No. of Protons – 2 No. of Neutrons – 2, No. of Electrons – | 12 |

395 | The graph of ( ln left(R / R_{0}right) ) versus ( ln A ) ( (R=text { radius of a nucleus and } A=mathrm{its} ) mass number) is then A. a straight line B. a parabola c. an ellipse D. none of them | 12 |

396 | The ratio of the velocity of an electron in the first Bohr’s orbit of the hydrogen atom and the velocity of light is: A . 1: 100 B. 1: 137 c. 1: 1000 D. 1: 10 | 12 |

397 | The significant result deduced from the Rutherford’s scattering experiment is that A. whole of the positive charge is concentrated at the centre of atom B. there are neutrons inside the nucleus C . ( alpha ) -particles are helium nuclei D. electrons are embedded in the atom E. electrons are revolving around the nucleus | 12 |

398 | What is the shortest wavelength present in the Paschen series of spectral lines? | 12 |

399 | The diagram below shows a cathode ray tube in which the arrow indicates a beam of charged particles approaching an electric field between the plates ( A ) and B. State the approximate voltage ( V_{1} ) used to heat the filament A . ( 1.5 mathrm{v} ) B. 3 ( c cdot 6 v ) D. 12 | 12 |

400 | Statement 1: A large number of alpha particles were deflected in the Rutherford experiment. Statement 2: Alpha particles that came close to the nucleus of the gold atoms were deflected. A. Both Statement 1 and Statement 2 are correct and Statement 2 is the correct explanation of Statement 1 B. Both Statement 1 and Statement 2 are correct and Statement 2 is not the correct explanation of Statement 1. c. statement 1 is correct but statement 2 is not correct D. Statement 1 is not correct but Statement 2 is correct E. Both the Statement 1 and Statement 2 are not correct | 12 |

401 | The ground state energy of hydrogen atom is ( -13.6 e V . ) If an electron make a transition from an energy level ( -0.85 e V ) to ( -1.51 e V ), calculate the wavelength of the spectral line emitted. To which series of hydrogen spectrum does this wavelength belong? | 12 |

402 | An element has number of proton ( =7 ) Then what will be its atomic number? A . 9 B. 7 ( c cdot 16 ) ( D ) | 12 |

403 | The radius of the first orbit of the ( e^{-} ) of a hydrogen atom is ( 5.3 times 10^{11} m ), what is the radius of its second orbit.? A. ( 3.12 times 10^{-10} mathrm{m} ) В. ( 2.12 times 10^{-10} mathrm{m} ) c. ( 4.12 times 10^{-10} mathrm{m} ) D. ( 5.12 times 10^{-10} mathrm{m} ) | 12 |

404 | Balmer gives an equation for wavelength of visible radiation of ( mathrm{H} ) spectrum as ( lambda=frac{k n^{2}}{n^{2}-4} . ) The value of in terms of Rydberg’s constant R is ( A cdot R ) B. 4R c. ( frac{R}{4} ) D. ( frac{4}{R} ) | 12 |

405 | Why is the screen of the cathode ray tube coated ? Name the material used for coating. A. florocent material. B. normal material c. highy resistive material D. none of these | 12 |

406 | The wave number of first line of Balmer series of hydrogen atom is ( 15200 mathrm{cm}^{-1} ) What is the wave number of first line of Balmer series of ( L i^{2+} ) ion. A. ( 15200 mathrm{cm}^{-1} ) В. ( 136800 m^{-1} ) c. ( 76000 mathrm{cm}^{-1} ) D. ( 13680 mathrm{cm}^{-1} ) | 12 |

407 | Which of the following was carried out by Rutherford in his experiment? A. Fast moving alpha-particles were made to fall on a thin silver foil. B. Fast moving beta-particles were made to fall on a thin gold foil C. Fast moving alpha-particles were made to fall on a thin gold foil D. Fast moving gamma-particles were made to fall on a thin gold foil | 12 |

408 | The energy required to transfer an electron from second Bohr orbit to third Bohr orbit in a hydrogen like atom with nuclear charge ( Z_{e} ) is ( 6.8 e V ) The wavelength of radiation required to shift the electron from first orbit to infinite orbit will be : A ( cdot 2.527 A^{circ} ) B . 25.27 A ( ^{circ} ) c. ( 252.7 A^{circ} ) D . 2527 A ( ^{circ} ) | 12 |

409 | The wavelength of radiation required to excite the electron from the first orbit to the third orbit in a doubly ionized lithium atom will be A ( .134 .25 AA ) В. ( 125.5 AA ) c. ( 113.7 AA ) | 12 |

410 | A 5 watt source emits monochromatic light of wavelength 5000 A when placed ( 0.5 mathrm{m} ) away, it liberates photoelectric from a photosensitive metallic surface. When the source is moved to a distance of ( 1.0 mathrm{m}, ) The numbers of photo electrons liberated will: A. be reduced by a factor of 2 B. be reduced by a factor of 4 c. be reduced by a factor of 8 D. be reduced by a factor of 16 | 12 |

411 | What voltage on ( y ) -plate will give such a deflection A ( .0 .11 V ) B. ( 1.1 V ) ( mathbf{c} cdot 11 V ) D. none | 12 |

412 | In the Bohr model of hydrogen atom, the ratio of the kinetic energy and total energy of electron in the ( n^{t h} ) quantum state will be A . 1 B. – – c. 2 D. -12 | 12 |

413 | In Rutherford’s scattering experiment if impact parameter is zero then angle of scatting for ( alpha ) particleis A ( .90^{circ} ) в. ( 270^{circ} ) ( c cdot 180^{circ} ) D. ( 0^{circ} ) | 12 |

414 | A high energy photon collides elastically with a charged particle (usually an electron)., The photon “bounces away” with less energy (a longer wavelength) The process described here is known as A. Compton scattering B. The photoelectric effect c. x-ray production D. Annihilation E. Quantum tunneling | 12 |

415 | If the potential energy of the electron in the first allowed orbit in hydrogen atom is ( E ; ) its This question has multiple correct options A. lonization potential is ( -E / 2 ) B. Kinetic energy is ( -E / 2 ) c. Total energy is ( E / 2 ) D. None of these | 12 |

416 | What is the purpose of anode in a Cathode ray tube? A. To provide potential energy to electrons B. To provide kinetic energy to protons C . To provide potential energy to protons D. To provide kinetic energy to electrons | 12 |

417 | In a muonic atom, a muon of mass of 200 times of that of electron and same charge is bond to the proton. The wavelengths of its Balmer series are in the range of A. X-rays B. infrared c. ( gamma ) rays D. microwaves | 12 |

418 | In a sample of hydrogen like atoms all of which are in ground state, a photon beam containing photons of various energies is passed.In absorption spectrum, five dark lies are observed. The number of bright lines in the emission spectrum will be (Assume that all transitions take place) A. 5 B. 10 c. 15 D. none of these | 12 |

419 | The ratio of specific charge ( e / m ) of an electron to that of a hydrogen ion is A . 1: 1 B. 1840: 1 c. 1: 1840 D. 2: 1 | 12 |

420 | Find the value of ( boldsymbol{T} times mathbf{1 0}^{mathbf{1 7}} ) where ( boldsymbol{T} ) is the orbital period of the electron? | 12 |

421 | In Rutherford’s alpha-ray scattering experiment, a screen is used to detect the alpha particles which is coated by A. carbon black B. platinum black c. zinc sulphide D. poly tetrafluoro ethylene | 12 |

422 | Which of them are atomic models? Thomsons plum puddling model Rutherfords nuclear model Bohrs model Sommerfelds model ( A cdot i & ) i B. i, ii & iii c. ii, ii & iv D. All of these | 12 |

423 | Total energy of an electron in the ground state of hydrogen atom is ( -13.6 e V ). Its total energy, when hydrogen atom is in the first excited state, is: ( mathbf{A} cdot+13.6 mathrm{eV} ) B. ( +3.4 e V ) c. ( -3.4 e V ) D. ( -54.4 e V ) | 12 |

424 | The potential energy between electron and proton is given by ( U=frac{K e^{2}}{3 r^{3}} ) According to Bohr’s theory, the energy in | 12 |

425 | How many sub-atomic particles are present in ana- particle used in Rutherford’s scattering experiment? A. Protons – 4, Neutrons – 0, Electrons – 0 B. Protons – 2, Neutrons – 0, Electron – 2 c. Protons – 2, Neutron – 2, Electron – 0 D. Protons – 2, Neutron – 2, Electron – 1 | 12 |

426 | Which of the following statement is true regarding Bohr’s Model of hydrogen atom? I. Orbiting speed of an electron decreases as it falls to discrete orbits away from the nucleus II. Radii of allowed orbits of electrons are proportional to the principal quantum number III. Frequency with which electrons orbit around the nucleus in discrete orbits is inversely proportional to the cube of principal quantum number ( I V . ) Binding force with which the electron is bound to nucleus increases as it shifts to outer orbits. Select the correct answer using the codes given below: A. ( I ) and ( I I I ) B. II and ( I V ) c. ( I, I I ) and ( I I I ) ( D ) and ( I V ) | 12 |

427 | Nucleon is a common name for A. Proton and electron B. electron and neutron c. neutron only D. neutron and proton | 12 |

428 | When a gold sheet is bombarded by a beam of ( alpha ) -particles, only a few of them get deflected whereas most go straight, undeflected because: This question has multiple correct options A. the force of attraction exerted on the ( alpha ) -particles by the oppositely charged electrons is not sufficient B. a nucleus has a much smaller volume than that of an atom c. the force of repulsion acting on the fast-moving ( alpha ) particles is very small D. the neutrons in the nucleus do not have any effect on the ( alpha ) -particles | 12 |

429 | In a cathode ray tube, what is the effect on the beam of particles if a hotter filament is used? A. Rate of electron emission remains unchanged B. Rate of electron emission decreases c. Rate of electron emission increases D. Rate of electron emission increases then decreases | 12 |

430 | ILLUSTRATION 29.2 What is the angular momentum of an electron in Bohr’s hydrogen atom whose energy is -3.4 eV? | 12 |

431 | If the first line of Lyman series has a wavelength ( 1215.4 A ), the first line of Balmer series is approximately ( mathbf{A} cdot 4864 hat{A} ) в. ( 1025.5 AA ) c. ( 6563 dot{h} ) D. 6400 月 | 12 |

432 | A photon is a/an A. Quantum of light B. Quantum of matter C. Positively charged paticle D. Instrument for measuring light intensity | 12 |

433 | A hydrogen atom is in the ( d ) -state. The values of ( m ) for this state are в. -3,-1,0,1,3 c. 2,1,0 D. -2,-1,0,1,2 | 12 |

434 | Write the postulates of Bohr’s atomic model. What is the relationship between the radii of the ( n ) th and first bohr orbit of hydrogen atom? | 12 |

435 | The fine structure of hydrogen spectrum can be explained by A. the presence of neutrons in the nucleus. B. the finite size of nucleus c. the orbital angular momentum of electrons. D. the spin angular momentum of electrons | 12 |

436 | A body of mass ( m ) is moving with constant velocity v along a line parallel to x-axis. The angular momentum with respect to origin. A. Remains constant B. Is zero c. Goes on decreasing D. Goes on increasing | 12 |

437 | Surface are of ( _{13} A l^{27} ) is ( S_{0}, ) then surface area of ( Z n^{64} ) is then A ( cdot frac{16}{9} S_{0} ) в. ( frac{4}{3} S_{0} ) c. ( frac{64}{27} S_{0} ) D. ( frac{3}{2} S_{0} ) | 12 |

438 | Number of spectral lines in hydrogen atom is A . 8 B. 6 c. 15 D. | 12 |

439 | Whenever a hydrogen atom emits a photon in the Balmer series A. It need not emit any more photon B. It may emit another photon in the Paschen series C. It must emit another photon in the Lyman series D. It may emit another photon on the Balmer series | 12 |

440 | The total of subshells in fourth energy level of an atom is A . 4 B. 8 ( c cdot 16 ) D. 32 | 12 |

441 | In Bohr’s theory of Hydrogen atom, the electronjumps from higher orbit ‘n’ to lower orbit ‘p’. The wavelength will be minimum for the transition ( A cdot n=5 ) to ( p=4 ) B. ( n=4 ) to ( p=3 ) ( c cdot n=3 ) to ( p=2 ) ( D cdot n=2 operatorname{top}=1 ) | 12 |

442 | A hydrogen atom emits a photon corresponding to an electron transition from ( n=5 ) to ( n=1 . ) The recoil speed of hydrogen atom is almost ( mathbf{A} cdot 10^{-4} m s^{-1} ) B. ( 2 times 10^{-2} mathrm{ms}^{-1} ) c. ( 4 m s^{-1} ) D. ( 8 times 10^{2} m s^{-1} ) | 12 |

443 | What are the ( alpha ) and ( beta ) particles emitted from ( _{90} T h^{228} rightarrow_{83} B i^{212} ) A. Four alpha and one beta B. Three alpha and seven beta c. Eight alpha and one beta D. one alpha and four beta | 12 |

444 | What is the rutherford’s atomic model? | 12 |

445 | A photon of energy ( 10.2 e V ) collides inelastically with ( H- ) atom in ground state. After a certain time interval of few ( mu s ) another photon of energy ( 15 e V ) collides inelastically with the same ( boldsymbol{H} ) atom, the observation made by a suitable detector is A. 1 photon with energy ( 10.2 e V ) and an electron with 1.4 ( e V ) B. Two photons with ( 10.2 e V ) C. Two photons with 1.4 eV D. one photon with 3.4 eV and 1 electron with 1.4 eV | 12 |

446 | ILLUSTRATION 29.10 The Ką X-ray emission line of tun occurs at 2 = 0.021 nm. What is the energy difference betw K and L levels in this atom? | 12 |

447 | A modified discharge tube is used as a A. cathode ray oscilloscope B. fluorescent tube c. x-ray tube D. all the above | 12 |

448 | According to the Bohr’s atomic model, the relation between principal quantum number (n) and radius of orbit(r) is? ( mathbf{A} cdot r propto n^{2} ) B. ( r propto frac{1}{n^{2}} ) c. ( _{r} propto frac{1}{n} ) D. ( r propto n ) | 12 |

449 | In the geiger-marsden experiment what percentage of the ( alpha ) particles were deflected by an angle more than ( 1^{circ} ) ( mathbf{A} cdot<0.15 % ) в. ( 99.85 % ) D. ( 100 % ) | 12 |

450 | If the series limit of Lymen series for hydrogen atom is equal to the series limit of Balmer series for a hydrogen like atom, then atomic number of this hydrogen like atom is A . 1 B. 2 ( c .3 ) D. 4 | 12 |

451 | According to Bohr’s theory of hydrogen- atom, for the electron in the ( n^{t h} ) permissible orbit This question has multiple correct options A ( cdot ) Linear Momentum ( propto frac{1}{n} ) B. Radius of orbit ( propto n ) c. Kinetic Energy ( propto frac{1}{n^{2}} ) D. Angular Momentum ( propto n ) | 12 |

452 | Answer the following question based on a hot cathode ray tube. Name the charged particles. | 12 |

453 | A strong argument for particle nature of cathode rays is that they A. Produce fluorescence B. Travel through vacuum C. Get deflected by electric and magnetic fields D. cast shadows | 12 |

454 | ( H-operatorname{atom} ) is of ( _{-}-_{-}—-k g ) ( mathbf{A} cdot 1.675 times 10^{-27} ) B . ( 1.673 times 10^{-27} ) C ( cdot 9.109 times 10^{-31} ) D. ( 3.348 times 10^{-27} ) | 12 |

455 | When a beam of white light is passed through sodium vapours and then through a spectrometer, spectrum so obtained has two dark lines present in the yellow region. This spectrum is called A. band spectrum B. continuous spectrum c. absorption spectrum of sodium D. emission spectrum of sodium | 12 |

456 | The collector plate in an experiment on photoelectric effect is kept vertically above the emitter plate. Light source is made on and a saturation photocurrent is recorded. An electric field is switched on which has a vertically downward direction. A. The photocurrent will increase B. The kinetic energy of the electrons will increase c. The stopping potential will decrease D. The threshold wavelength will increase | 12 |

457 | The absorption transition between the first and the fourth energy states of hydrogen atom are 3. The emission transition between these states will be: A . 3 B. 4 ( c .5 ) D. 6 | 12 |

458 | The adjoining diagram shows the energy levels for an electron in a certain, which transition shown represents the emission of a photon with the maximum energy ( A ) B. I c. III D. IV | 12 |

459 | State whether true or false: ( underline{e} ) ratio of proton is greater than that of ( bar{m} ) electron. A . True B. False | 12 |

460 | The difference in maximum kinetic energy of photoelectrons from the ( A ) and from B A. increases with increases in ( E ) B. decreases with decreases in ( E ) c. first increases than decrease with increase in ( E ) D. remain constant | 12 |

461 | When is ( H_{alpha} ) line in the emission spectrum of hydrogen atom obtained? Calculate the frequency of the photon emitted during this transition. | 12 |

462 | 1. An energy of 24.6 eV is required to remove one of the electrons from a neutral helium atom. The energy eV) required to remove both the electrons from a neutral helium atom is (a) 79.0 (b) 51.8 (c) 49.2 (d) 38.2 | 12 |

463 | A light paddle wheel placed in the path of ( quad ) will rotate A. cathode rays B. ( alpha ) -rays c. ( beta ) -rays D. all the above | 12 |

464 | Branch of study involving rearrangement of atoms and making nano-materials is known as? A. Mechanical engg. B. Chemical engg. c. Electrical engg. D. Nanotechnology | 12 |

465 | Hydrogen atom excites energy level from fundamental state to ( n=3 ) Number of spectral lines according to Bohr, is A . 4 B. 3 c. 1 D. | 12 |

466 | Assuming that in an atom, neutron ( left(m_{n}right) ) and electron ( left(m_{e}right) ) are bound to each other by gravitational force only and electron are moving around neutron and assuming Bohr’s quantization rule to be valid.The expression for energy of electron in ( n^{t h} ) level comes out to be ( left.frac{(a-4) G^{2} m_{n}^{2} m_{e}^{2}}{4 n^{2} h^{2}} V quad text { (where } h=frac{h}{2 pi}right) ) Find the value of ‘ ( a ) ‘ | 12 |

467 | Cathode ray particles have a mass of times that of hydrogen nucleus. ( mathbf{A} cdot mathbf{1} ) B. ( frac{1}{10} ) ( c .1840 ) D. ( frac{1}{1840} ) | 12 |

468 | The ratio of the specific charge (e/m) of a proton to that of an ( alpha ) particle is A . 1: 2 B . ( 1: 1 / 4 ) ( c cdot 1: 4 ) D. 1:1/2 | 12 |

469 | The adjoining diagram shows the spectral energy density distribution ( boldsymbol{E}_{lambda} ) of a black body at two different temperatures. If the areas under the curves are in the ratio ( 16: 1, ) the value of temperature ( boldsymbol{T} ) is : A . ( 32,000 K ) в. 16,000 К c. ( 8,000 K ) D. 4,000 К | 12 |

470 | The idea of quantum nature of light has emerged in an attempt to explain: A . interference B. diffraction c. black body radiation D. polarisation | 12 |

471 | Thomson experimented with A. protrons B. cathode rays c. alpha particles D. gold foil | 12 |

472 | A hydrogen atom is in the excited state of the principal quantum number ( n . ) It emits a photon of wavelength ( ^{prime} lambda^{prime} ) when returns to ground state. The value of ( n ) is ( mathbf{A} cdot sqrt{lambda R(lambda R-1)} ) B. ( sqrt{frac{lambda R-1}{lambda R}} ) ( mathbf{c} cdot sqrt{frac{lambda R}{lambda R-1}} ) D. ( sqrt{lambda(R-1)} ) | 12 |

473 | An element has number of electrons ( =2 ) Then what will be its atomic number? ( mathbf{A} cdot mathbf{1} ) B. 4 ( c cdot 3 ) ( D ) | 12 |

474 | which an electron in hydrogen atom jumps from the third excited state to the ground state | 12 |

475 | If a diffraction peak is observed when electrons are incident at an angle ( ^{prime} boldsymbol{i}^{prime} ) from the normal to the crystal planes with distance ‘ ( d^{prime} ) between them (see figure), de-Broglie wavelength ( lambda_{d B} ) of electrons can be calculated by the relationship ( (n text { is an integer }) ) ( mathbf{A} cdot d sin i=n lambda_{d B} ) B . ( 2 d cos i=n lambda_{d B} ) ( mathbf{c} cdot 2 d sin i=n lambda_{d B} ) ( mathbf{D} cdot d cos i=n lambda_{d B} ) | 12 |

476 | An electron in a hydrogen atom makes a transition from ( n=n_{1} ) to ( n=n_{2} . ) The time period of the electron in the initial state is eight times that in the final state. The possible values of ( n_{1} ) and ( n_{2} ) are This question has multiple correct options ( mathbf{A} cdot n_{1}=4, n_{2}=2 ) B ( . n_{1}=8, n_{2}=2 ) c. ( n_{1}=8, n_{2}=1 ) D ( cdot n_{1}=6, n_{2}=3 ) | 12 |

477 | What voltage on ( y ) -plate will give such a deflection A ( .0 .11 V ) B. ( 1.1 V ) ( mathbf{c} cdot 11 V ) D. none | 12 |

478 | The radius of nucleus varies with mass no. as ( A^{1 / n} . ) The value of ( n ) is : | 12 |

479 | In Rutherford’s scattering experiment which of the following does not happen? A. Most of the ( alpha ) -rays pass through without deflection B. A few ( alpha ) -particles pass through the nucleus C. A few ( alpha ) -particles are deflected back D. ( alpha ) -particles going near the nucleus are slightly deflected | 12 |

480 | according to Ruther-fordis atomic model, the mass of the atom is evenly distributed throughout the atom A. True B. False | 12 |

481 | In ( 1 g ) of a solid, there are ( 5 times 10^{21} ) atoms. If one electron is removed from energy of ( 0.01 % ) atoms of the solid, the charge gained by the solid is : (electronic charge is ( left.1.6 times 10^{19} Cright) ) ( mathbf{A} cdot+0.08 C ) B. ( +0.8 C ) ( c .-0.08 C ) D. ( -0.8 C ) | 12 |

482 | If energy required to remove one of the two electron from He atom is ( 29.5 e V ) then what is the value of energy required to convert a helium atom into ( boldsymbol{alpha}- ) particle? A . ( 54.4 e V ) B. ( 83.9 e V ) c. ( 29.5 e V ) D. 24.9eV | 12 |

483 | Which of the air pressures is appropriate for the production of cathode rays in the discharge tube? ( A cdot 1 mathrm{cm} ) нв B. ( 1 mathrm{mm} ) Нg c. ( 0.001 mathrm{cm} ) Hg D. 0.001 ( mathrm{mm} ) ну | 12 |

484 | The nuclear radius is of the order of B. ( 10^{-6} ) m ( mathbf{c} cdot 10^{-15} m ) D. ( 10^{-14} m ) | 12 |

485 | Diagram shows an electron gun inside a cathode ray tube. Which of the following is true? A. F is Filament, to heat the cathode B. ( x ) is Cathode, to emit the electrons C. ( Y ) is Anode, to provide kinetic energy to electrons D. All the above | 12 |

486 | A proton and an ( alpha ) particle having equal kinetic energy are projected in a uniform transverse electric field as shown in figure A. Proton trajectory is more curved B. ( alpha ) particle trajectory is more curve C. Both trajectories are equally curved but in opposite direction D. Both trajectories are equally curved and in same direction | 12 |

487 | In a Geiger Marsden experiment, calculate the distance of closest approach to the nucleus of ( Z=mathbf{7 5} ) when an ( alpha ) -particle of ( 5 M e V ) energy impinges on it before it comes momentarily to rest and reverse its direction. How will the distance of closest approach be affected when the kinetic energy of the ( alpha ) -particle is doubled? | 12 |

488 | Draw a simplified labelled diagram of a hot cathode ray tube. | 12 |

489 | The transition from the state ( n=4 ) to ( boldsymbol{n}=mathbf{3} ) in a hydrogen like atom results in ultraviolet radiation. Infrared radiation will be obtained in the transition from ( mathbf{A} cdot 2 rightarrow 1 ) B . ( 3 rightarrow 2 ) c. ( 4 rightarrow 2 ) D. ( 5 rightarrow 4 ) | 12 |

490 | ( U^{235}, U^{238}, U^{239} ) are the atoms of the uranium. Which are called as A. Isomers B. Isobars c. Isotopes D. None of these | 12 |

491 | The short wavelength limit for the Lyman series of the hydrogen spectrum is 913.4 A.Calculate the short wavelength limit from Balmer series of the hydrogen spectrum. | 12 |

492 | Particles having half integral spin are : This question has multiple correct options A . Electron B. Photon c. Proton D. Neutron | 12 |

493 | The number of different wavelengths that is possible to be observed in the spectrum from a hydrogen sample if the atoms are excited to third excited state is: A . 3 B. 4 c. 5 D. 6 | 12 |

494 | The speed of electrons in the second orbit of ( B e^{3+} ) ion will be A ( cdot frac{c}{137} ) в. ( frac{2 c}{137} ) c. ( frac{3 c}{137} ) D. ( frac{4 c}{137} ) | 12 |

495 | The components used in Rutherford’s experiment: ( mathbf{A} cdot beta ) -particles, which impinged on a metal foil and got absorbed B. ( gamma ) -rays, which impinged on a metal foil and ejected electrons C. helium atoms, which impinged on a metal foil and got scattered D. helium nuclei, which impinged on a metal foil and got scattered | 12 |

496 | The radius of first Bohr orbit in hydrogen atom is ( r_{0} ) then the radius of first orbit in helium atom will be A ( .2 r_{0} ) B. ( 4 r_{0} ) c. ( frac{r_{0}}{2} ) D. ( r ) | 12 |

497 | With the help of a neat labelled diagram, describe the Geiger- Marsden experiment. What is mass defect? The photoelectric work function for a metal surface is ( 2.3 mathrm{eV} ). If the light of wavelength ( 6800 A^{circ} ) is incident on the surface of metal find threshold frequency and incident frequency. Will there be an emission of photoelectrons or not? [Velocity of light ( c=3 times 10^{8} m / s ) Planck’s constant, ( boldsymbol{h}=mathbf{6} cdot mathbf{6 3} times mathbf{1 0}^{-mathbf{3 4}} mathbf{J s} ) | 12 |

498 | ILLUSTRATION 29.3 Suppose potential energy between electron and proton at separation r is given by U = k log r, where k is a constant. For such a hypothetical hydrogen atom, calculate the radius of nth Bohr’s orbit and its energy levels. U k | 12 |

499 | ne / ( m ) experiment we assume nature of electron as A. wave B. particle. c. photon D. both a and b | 12 |

500 | A free nucleus of mass 24 amu, intially at rest emits a gamma photon. The energy of the photon is ( 7 M e V ). The kinetic energy of recoiling nucleus is approximately equal to [Take; 1 am ( u= ) ( mathbf{9 . 3 1} boldsymbol{M e V} ) A . ( 3.3 k e V ) B. 4.4keV c. ( 1.1 k e V ) D. 2.5keV | 12 |

501 | The recoil speed of a hydrogen atom after it emits a photon in going from ( boldsymbol{n}=mathbf{5} ) state to ( boldsymbol{n}=mathbf{1} ) state is ( mathbf{A} cdot 4.718 mathrm{m} mathrm{s}^{-1} ) B. ( 7.418 mathrm{m} mathrm{s}^{-1} ) c. ( 4.178 mathrm{m} mathrm{s}^{-1} ) D. ( 7.148 mathrm{m} mathrm{s}^{-1} ) | 12 |

502 | In Rutherford’s alpha scattering experiment: This question has multiple correct options | 12 |

503 | How many electrons, protons and neutrons are there in ( 16 g ) of ( _{8} O^{16} ? ) | 12 |

504 | The lifetime of an electron in the state ( boldsymbol{n}=2 ) in the hydrogen atom is about ( mathbf{A} cdot 10 n s ) в. 1000 ns ( c cdot 1 m s ) D. ( 10 m s ) | 12 |

505 | the ground state energy of hydrogen atom is ( -13.6 mathrm{eV} ). the energy of second excited state of ( H e^{+} ) ion in eV is : ( mathbf{A} cdot-27.2 ) в. -3.4 c. -54.4 D . -6.04 | 12 |

506 | The wavelength of the first line of Lyman series for hydrogen is identical to that of the second line of Balmer series for some hydrogen-like ion ( X ). Calculate energies of the first four levels of ( boldsymbol{X} ) Also, find its ionization potential. (Given: Ground state binding energy of the hydrogen atom is ( 13.6 e V ) ) | 12 |

507 | A proton of mass ‘ ( m^{prime} ) moving with a speed ‘ ( v_{0}^{prime} ) approaches a stationary proton that is free to move. Assume impact parameter to be zero, i.e. headon collision. How close will the incident proton go to other proton? A ( cdot frac{epsilon^{3}}{pi epsilon_{0} m^{2} v_{0}} ) В. ( frac{epsilon^{3}}{pi epsilon_{0} m v_{0}} ) ( ^{mathrm{C}} frac{epsilon^{2}}{pi epsilon_{0} m v_{0}^{2}} ) D. None of the above | 12 |

508 | A Proton and an / alpha particle are accelerated through a potential difference of ( 100 mathrm{V} ). The ratio of the wavelength associated with the proton to that associated with an / alpha particle is A .1: 2 B . 2: 1 ( mathbf{c} cdot 22: 1 ) D. ( 2 sqrt{2}: 1 ) | 12 |

509 | ILLUSTRATION 29.7 A hydrogen atom is in the third excited state. It makes a transition to a different state and a photon is either absorbed or emitted. Determine the quantum number ng of the final state and the energy of the photon if it is (a) emitted with the shortest possible wavelength, (b) emitted with the longest possible wavelength, and (c) absorbed with the longest possible wavelength. | 12 |

510 | The energy of the electron of hydrogen atom in its nth orbit is given by ( boldsymbol{E}_{boldsymbol{n}}= ) ( -frac{13.6}{n^{2}} ) electron volt(eV). Based on this formula (i) Draw different energy levels corresponding to ( n=1,2,3,4,5,6 ) and ( infty ) (ii) Show Lyman and Baler series of emission spectrum of hydrogen atom by drawing various electronic transitions. (iii) Find the ionisation energy of hydrogen atom. | 12 |

511 | An alpha nucleus of energy ( frac{1}{2} m v^{2} ) bombards a heavy nuclear target of charge Ze. Then the distance of closest approach for the alpha nucleus will be proportional to A ( cdot v^{2} ) в. ( frac{1}{m} ) c. ( frac{1}{v^{4}} ) D. ( frac{1}{Z e} ) | 12 |

512 | The ionization energy of the hydrogen atom is ( 13.6 e V . ) The potential energy of the eletron in ( n=2 ) state of hydrogen atom is A. ( +3.4 e V ) в. -3.4eV ( mathrm{c} .+6.8 mathrm{eV} ) D. – ( 6.8 e V ) | 12 |

513 | Which of the following statement about hydrogen spectrum are correct? This question has multiple correct options A. All the lines of Lyman series lie in ultraviolet region B. All the lines of Balmer series lie in visible region C. All the lines of Paschen series lie in infrared region D. None of the above | 12 |

514 | Linear momentum of an electron in Bohr orbit of H-atom (principal quantum number ( n ) ) is proportional to: A ( cdot frac{1}{n^{2}} ) B. ( frac{1}{n} ) ( c ) ( mathbf{D} cdot n^{2} ) | 12 |

515 | Whenever a hydrogen atom emits a photon in the Balmer series, This question has multiple correct options A. it may emit another photon in the Balmer series. B. it must emit another photon in the Lyman series. C. the second photon, it emitted, will have a wavelength of about ( 122 mathrm{nm} ) D. it may emit a second photon, but the wavelength of this photon cannot be predicted. | 12 |

516 | In an electron transition inside a hydrogen atom, orbital angular momentum may change by ( ( h= ) Planck constant) This question has multiple correct options ( A cdot h ) в. ( frac{h}{pi} ) c. ( frac{h}{2 pi} ) D. ( frac{h}{4 pi} ) | 12 |

517 | Identify what happens to a stream of ( alpha ) particles that is shoot at a thin sheet of gold foil in a rutherford experiment? A. All of the particles pass straight through B. A few of the particles bounce back at ( 180^{circ} ) C. All of the particles bounce back at ( 180^{circ} ) D. Most of the particles are absorbed by the foil E. None of the particles are deflected by more than ( 45^{circ} ) | 12 |

518 | Hydrogen atom emits blue light when it jumps from ( n=4 ) energy level to the ( n= ) 2 level. Which colour of light would the atom emit when it changes from the ( n= ) 5 level to the ( n=2 ) level? A . Red B. Yellow c. Green D. Violet | 12 |

519 | If ( 13.6 e V ) energy is required to ionize the hydrogen atom, then the energy required to remove an electron from ( boldsymbol{n}=mathbf{2} ) is A. ( 10.2 mathrm{eV} ) B. 0 eV c. 3.4 eV D. 6.8 eV | 12 |

520 | The quantum number corresponding to orbit of diameter ( 0.0001 mathrm{mm} ) in hydrogen atom will be nearly (Given that the radius of orbit with ( n=1 ) is ( 0.51 times ) ( left.mathbf{1 0}^{-mathbf{1 0}}right): ) A . 39 B. 31 ( c cdot 9 ) D. 49 | 12 |

521 | When alpha particles are sent through a thin metal foil, most of them go straight through the foil because: A. alpha particles are much heavier than electrons B. alpha particles are positively charged c. most part of the atom is empty space D. alpha particle move with high velocity | 12 |

522 | An electron is moving in an orbit of a hydrogen atom from which there can be a maximum of six transitions. An electron is moving in an orbit of another hydrogen atom from which there can be a maximum of three transitions. The ratio of the velocity of the electron in these two orbits is ( mathbf{A} cdot frac{1}{2} ) B. ( frac{2}{1} ) ( mathbf{c} cdot underline{5} ) D. ( frac{3}{4} ) | 12 |

523 | If ( E_{1}, E_{2} ) and ( E_{3} ) are the respective kinetic energies of an electron, an alpha particle and a proton each having the same de Brogli wavelength then A. ( E_{1}>E_{3}>E_{2} ) B . ( E_{2}>E_{3}>E_{1} ) c. ( E_{1}>E_{2}>E_{3} ) D. ( E_{1}=E_{2}=E_{3} ) | 12 |

524 | A stream of electrons enters an electrical field normal to the lines of force with a velocity of ( 3 times 10^{7} m / s ). The electric intensity is ( 1800 v / m ) While traveling through a distance of 10 ( c m, ) the electron beam is deflected by 2 mm. Then ( e / m ) value in coulomb per ( mathrm{kg} ) is A ( cdot 2 times 10^{10} ) B. ( 2 times 10^{7} ) ( c cdot 2 times 10^{11} ) D. ( 2 times 10^{4} ) | 12 |

525 | Which person had convinced people that matter could be divided forever? A. Dalton B. Democritus c. Thomson D. Aristotle E. Rutherford | 12 |

526 | Which of the following is not a conclusion of Rutherford experiment? A. An atom has a very small compact nucleus B. An atom is mainly empty space C. An atom’s mass is concentrated in the nucleus D. An atom has a very dense nucleus E. An atom has a negatively charged nucleus | 12 |

527 | In a hydrogen like atom, when an electron jumps from the M-shell to the L-shell, the wavelength of emitted radiation is ( lambda ). If an electron jumps from N-shell to the L-shell, the wavelength of emitted radiation will be? A ( cdot frac{27}{20} lambda ) в. ( frac{16}{25} lambda ) c. ( frac{20}{27} lambda ) D. ( frac{25}{16} lambda ) | 12 |

528 | Mark out the incorrect statement: A. A free neutron can transform itself into photon B. A free proton can transform itself into neutron C. In beta minus decay, the electron originates from nucleus D. All of the above | 12 |

529 | If the frequency or revolution of the electron in first Bohr orbit of a H-atom is ( 6.6 times 10^{15} mathrm{Hz} ), the frequency in the next orbit is A ( cdot 13.2 times 10^{15} ) Н 2 В. ( 43.50 times 10^{30} ) Нz c. ( 0.8 times 10^{15} ) Н ( z ) D. ( 1.65 times 10^{15} ) Н ( z ) | 12 |

530 | The energy levels of a certain atom for 1st, 2nd and 3rd levels are ( mathrm{E}, 4 mathrm{E}_{1 rightarrow 3} ) and 2E respectively. A photon of wavelength ( lambda ) is emitted for a transition ( 3 rightarrow 1 ) What will be the wavelength of emissions for transition ( 2 rightarrow 1: ) ( A cdot lambda / 3 ) в. ( 4 lambda / 3 ) c. ( 3 lambda / 4 ) D. ( 3 lambda ) | 12 |

531 | Two nuclei have mass numbers in the ratio ( 1: 64 . ) What is the ratio of their nuclear radii ? | 12 |

532 | In Rutherford experiment, most of the alpha particles go straight through the foil because: A. alpha particles are much heavier than electrons B. alpha particles are positively charged c. most part of the atom is empty space D. alpha particles move with high velocity | 12 |

533 | lonized hydrogen atoms and ( alpha ) -particles with same momenta enters perpendicular to a constant magnetic field, B. The ratio of their radii of their paths ( r_{H}: r_{alpha} ) will be : A .2: 1 B. 1: 2 c. 4: 1 D. 1: 4 | 12 |

534 | Radiation coming from transitions ( n= ) 2 to ( n=1 ) of hydrogen atoms falls on helium ions in ( n=1 ) and ( n=2 ) states. What are the possible transition of helium ions as they absorb energy from the radiation? | 12 |

535 | The allowed energy for the particle for a particular value of ( n ) is proportional to A ( cdot a^{-2} ) B ( cdot a^{-3 / 2} ) ( c cdot a^{-1} ) D. ( a^{2} ) | 12 |

536 | When an alpha particle is emitted from a radioactive source. A. Its atomic number increases by 4 B. Its atomic number decreases by 2 c. Its atomic number increases by 2 D. It atomic number decreases by 4 | 12 |

537 | The angular momentum of the electron in hydrogen atom in the ground state is ( mathbf{A} cdot 2 h ) в. ( frac{h}{2} ) c. ( frac{h}{2 pi} ) D. ( frac{h}{4 pi} ) | 12 |

538 | Find the velocity of an electron having an energy of 1280 electron volt. ( boldsymbol{m}= ) ( 9.1 times 10^{-31} k g ) | 12 |

539 | In 1911 , the physicist Ernest Rutherford discovered that atoms have a tiny, dense nucleus by shooting pisitively charged particular at a very thin gold foil. A key physical property which led Rutherford to use gold that it was A. Electrically conducting B. Highly malleable c. shiny D. none-rective | 12 |

540 | Bohr’s atom model assumes. A. The nucleus is of infinite mass and is at rest B. Electrons in a quantized orbit will not radiate energy C. Mass of electron remains constant D. All the above. | 12 |

541 | Which of the following can produced emission spectrum? A. electrons in an excited gas jump up to a higher energy level and release photons. B. electrons in an excited gas jump down to a lower energy level and release photons. c. electrons are released from the outer orbitals of an excited gas. D. an unstable nucleus releases energy. E. light is shined on a metal surface and electrons are released. | 12 |

542 | The spin of photon is A. B. ( frac{1}{2} ) c. ( frac{1}{3} ) D. None | 12 |

543 | What were the three major observations Rutherford made in the gold foil experiment? | 12 |

544 | The conclusions of Rutherford’s scattering experiment are: A. nucleus is very small in size B. nucleus is very heavy and carries positive charge C. most of the space in the atom is empty D. All of the above | 12 |

545 | In the above figure, ( boldsymbol{E}_{1} ) to ( boldsymbol{E}_{6} ) represent some of the energy levels of an electron in the hydrogen atom. Which one of the following transitions produces a photon of wavelength in the ultra-violet region of the electromagnetic spectrum? ( e V ) ( 85 mathrm{eV} ) A ( . E_{2}-E_{1} ) в. ( E_{3}-E_{2} ) ( mathbf{c} cdot E_{4}-E_{3} ) D. ( E_{6}-E_{4} ) | 12 |

546 | The angular momentum of electron in hydrogen atom is proportional to A ( cdot sqrt{r} ) B. ( frac{1}{r} ) c. ( r^{2} ) D. ( frac{1}{sqrt{r}} ) | 12 |

547 | In a process a neutron which is initially at rest, decays into a proton, an electron and an antineutrino. The ejected electron has a momentum of ( boldsymbol{p}_{1}= ) ( 2.4 times 10^{-26} k g m / s ) and the antineutrino has ( p_{2}=7.0 times 10^{-27} k g m / s . ) Find the recoil speed of the proton if the electron and the antineutrino are ejected (a) along the same direction (b) in mutually perpendicular directions (Mass of the proton ( boldsymbol{m}_{boldsymbol{p}}=mathbf{1 . 6 7} times mathbf{1 0}^{-mathbf{2 7}} ) | 12 |

548 | ( alpha- ) particles of 6 MeV energy is scattered back from a silver foil. Calculate the maximum volume where the entire charge of the atom is supposed to be accumulated. ( [Z text { for silver }=47] ) A . ( 3.6 times 10^{-28} mathrm{m}^{3} ) В. ( 5.97 times 10^{-42} mathrm{m}^{3} ) c. ( 6.55 times 10^{-71} m^{3} ) D. ( 48 times 10^{-42} m^{3} ) | 12 |

549 | Find the radius of a ( H e^{+} ) ion in the state ( boldsymbol{n}=mathbf{1} ) | 12 |

550 | Pick out correct statement from the following regarding photons: A. Zero rest mass and zero spin B. Zero rest mass and half integral spin c. zero rest mass and spin of unity D. Unit rest mass and spin of unity | 12 |

551 | The difference in maximum kinetic energy of photoelectrons from the ( A ) and from B A. increases with increases in ( E ) B. decreases with decreases in ( E ) c. first increases than decrease with increase in ( E ) D. remain constant | 12 |

552 | When a hydrogen atom is raised from the ground state to and excited state A. P.E increases and K.E decreases B. P.E decreases and K.E increases c. Both energy (K.E and P.E) increases D. Both K.E and P.E decreases | 12 |

553 | The ionization potential of the hydrogen atom is ( 13.6 mathrm{V} ). The energy needed to ionize a hydrogen atom which is in its second excited state is about A. 3.4 ev B. 2.5 ev c. ( 10.2 mathrm{ev} ) D. 13.6 ev | 12 |

554 | Three photons coming from emission spectra of hydrogen sample are picked up. Their energies are ( 12.1 e V, 10.2 e V ) and ( 1.9 e V . ) These photons must come from A. a single atom B. two atoms c. three atom D. either two atoms or three atoms | 12 |

555 | In a hydrogen atom, electron is in the ( n^{t h} ) excited state. It comes down to the first excited state by emitting 10 different wavelengths. The value of ( n^{t h} ) is A. 6 B. 7 c. 8 D. | 12 |

556 | In Thomsons experiment for determining e/m, the potential difference between the cathode and the anode is same as that between the deflecting plates ( in the region of crossed fields). If the potential difference is doubled. Then the factor by which the magnetic field be increased to ensure that the electron beam remains undeflected is: A ( cdot sqrt{2} ) B. 2 ( c cdot 2 sqrt{2} ) ( D cdot 4 ) | 12 |

557 | The difference between I and II energy levels is A ( cdot 1.5 times 10^{-18} mathrm{J} ) B ( .3 times 10^{-18} J ) c ( cdot 6 times 10^{-18} J ) D. ( 12 times 10^{-18} mathrm{J} ) | 12 |

558 | Use the relationship between radius of a nucleus and its mass number. Example: Find the radius of the nucleus of an atom of mass number ( 216left(R_{0}=right. ) | 12 |

559 | The electric potential energy between a proton and an electron is given by ( U= ) ( U_{0} l n frac{r}{r_{0}}, ) where ( r_{0} ) is a constant. Assuming Bohr’s model to be applicable, write the variation of ( ^{prime} boldsymbol{r}^{prime} ) with ( n, n ) being the principal quantum number. ( mathbf{A} cdot r_{n} propto n ) ( mathbf{B} cdot r_{n} propto 1 / n ) c. ( r_{n} propto n^{2} ) D. ( r_{n} propto 1 / n^{2} ) | 12 |

560 | We consider the Thomson model of the hydrogen atom in which the proton is distributed uniformly over a spherical volume of radius 0.25 angstrom. Applying the Bohr’s condition in this model the ground state energy (in eV) of the electron will be close to : A. ( -frac{13.6}{4} ) B . -13.6 c. ( -frac{13.6}{2} ) D. ( -2 times 13.6 ) | 12 |

561 | Taking the wavelength of first Balmer line in hydrogen spectrum ( (n=3 ) to ( boldsymbol{n}=2) ) as ( 660 n m, ) the wavelength of the 2nd Balmer line ( (n=4 text { to } n=2) ) will be: ( mathbf{A} cdot 889.2 n m ) B. ( 642.7 n m ) ( mathbf{c} .488 .9 n m ) D. ( 388.9 n m ) | 12 |

562 | Assertion The force of repulsion between atomic nucleus and ( alpha ) -particle varies with distance according to inverse square law. Reason Rutherford did ( alpha ) -particle scattering experiment. A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion c. Assertion is correct but Reason is incorrect D. Both Assertion and Reason are incorrect | 12 |

563 | In the Bohr’s model of hydrogenlike atom the force between the nucleus and the electron is modified as [ boldsymbol{F}=frac{boldsymbol{e}^{2}}{boldsymbol{4} boldsymbol{pi} varepsilon_{0}}left(frac{1}{boldsymbol{r}^{2}}+frac{boldsymbol{beta}}{boldsymbol{r}^{3}}right), text { where } boldsymbol{beta} text { is a } ] constant. For this atom, the radius of the ( n ) th orbit in terms of the Bohr radius [ left(a_{0}=frac{varepsilon_{0} h^{2}}{m pi e^{2}}right) i s ] A ( cdot r_{n}=a_{0} n-beta ) ( mathbf{B} cdot r_{n}=a_{0} n^{2}+beta ) ( mathbf{c} cdot r_{n}=a_{0} n^{2}-beta ) ( mathbf{D} cdot r_{n}=a_{0} n+beta ) | 12 |

564 | Rutherford’s alpha particle scattering experiment established that: A. protons are not evenly distributed throughout an atom B. electrons have a negative charge c. electrons have a positive charge D. atoms are made of protons, neutrons, and electrons | 12 |

565 | Ultraviolet light of wavelength ( lambda_{1} ) and ( lambda_{2} ) when allowed to fall on hydrogen atoms in their ground state is found to liberate electron with kinetic energy ( 1.8 e V ) and 4.0 ( e V ) respectively. Find the value of ( frac{lambda_{1}}{lambda_{2}} ) A ( -frac{7}{8} ) B. ( frac{8}{7} ) c. ( frac{9}{20} ) D. ( frac{20}{9} ) | 12 |

566 | If the series limit of the Balmer series for hydrogen is 2700 Angstrom. Calculate the atomic no. of the element which gives X-ray wavelength of ( boldsymbol{K}_{boldsymbol{alpha}} ) line as 1.0 Angstrom. ( A cdot z=21 ) B. ( z=31 ) ( c cdot z=61 ) ( D cdot z=5 ) | 12 |

567 | From lyman series of Pfund series, frequency A. increase B. decrease c. increase or decrease D. no change | 12 |

568 | (i) Why is a cathode ray tube evacuated to a low pressure? (ii) What happens if the negative potential is changed on a grid? | 12 |

569 | The total energy of an electron revolving in the second orbit of hydrogen atom is? A. -13.6 ev B. -1.51 eV c. -3.4 ev D. zero | 12 |

570 | As per bohr model, the minimum energy (in eV) required to remove an electron from the ground state of double ionized Li atom(Z=3) is: A . 1.5 B. 13.6 ( c . ) 50.8 D. 122.4 | 12 |

571 | The total energy of in the electron in the hydrogen atom in the ground state is ( -13.6 e V . ) Which of the following is its kinetic energy in the first exited state? A. 13.6 eV B. 6.8 eV c. ( 3.4 e V ) D. 1.825 eV | 12 |

572 | How can the brightness of the pattern on the screen or cathode ray tube be changed? A. By changing the negative potential on grid B. By changing the positive potential on grid c. we can’t increase the brightness D. None of the above | 12 |

573 | The diagram below shows a cathode ray tube in which the arrow indicates a beam of charged particles approaching an electric field between the plates ( A ) and B. State the amount of charge on each particle. A ( cdot 1.6 times 10^{-19} mathrm{C} ) в. ( -1.6 times 10^{-19} mathrm{C} ) ( c ) D. ( -1.16 times 10^{-19} C ) | 12 |

574 | An electron of kinetic energy ( boldsymbol{E}_{mathbf{0}} ) is scattered by an atomic hydrogen sample in ground state. The minimum value of ( E_{0}, ) so that a photon of wavelength 656.3 nm may be emitted by ( boldsymbol{H}- ) atom is : A. 12.09 eV в. 13.6 eV c. ( 14.6 e V ) D. none of these | 12 |

575 | According to Rutherford’s ( alpha ) -scattering experiment, which of the following statement is true? A. The electrons in the gold foil absorbed the alpha particles and changed energy levels. B. Most of the alpha particles passed through the foil undeflected. C. A few of the alpha particles knocked the nucleus completely out of the atom. D. A large percentage of alpha pantries were turned back when striking the foil E. The gold foil began to emit a bright-line spectrum. | 12 |

576 | In the discharge tube as the density of atom increases, the intensity spectral lines A. Decreases continuously B. Increases continuously c. Remains constant D. None of these | 12 |

577 | When a hydrogen atom is in its first excited level, its radius is A. four times its ground state radius B. twice times its ground state radius c. same times its ground state radius D. half times its ground state radius | 12 |

578 | To get line spectrum, the substances are excited in their A. Solid state B. Molecular state c. Gaseous state D. Atomic state | 12 |

579 | When an ( alpha ) -particle of mass ‘ ( m^{prime} ) moving with velocity ( ^{prime} v^{prime} ) bombards on a heavy nucleus of charge ( ^{prime} Z e^{prime}, ) its distance of closest approach from the nucleus depends on ( m ) as: A ( cdot frac{1}{m} ) в. ( frac{1}{sqrt{m}} ) c. ( frac{1}{m^{2}} ) D. ( m ) | 12 |

580 | If the pressure within a discharge tube is reduced from ( 10^{-3} ) mm to ( 10^{-4} ) mm mercury then the rays which are produced perpendicular to the cathode surface are known as A. Anode rays B. Cathode rays c. x-rays D. canal rays | 12 |

581 | An electron is at rest. Its wavelength is ( A cdot 1 ) B. Infinity c. ( frac{h}{m_{e}} ) D. It has not wave character | 12 |

582 | ( 0.38 e v_{-1-}-n 6 ) ( 0.54 e v_{-}–n 5 ) ( 0.85 e v_{-}—n 4 ) ( 1.52 e v_{-}–n 3 ) ( 3.39 e v_{-1-}-n 2 ) 13.6ev ( boldsymbol{n} mathbf{1} ) A hydrogen electron falls from the ( n=3 ) to the ( n=1 ) energy level. Using the chart above, determine how much energy it must release: ( mathbf{A} cdot+0.97 e V ) B. ( +2.85 e V ) ( mathbf{c} cdot+10.29 e V ) D. +12.08 eV E . ( +13.06 mathrm{eV} ) | 12 |

583 | In ( _{88} R a^{226} ) nucleus there are A. 226 protons and 88 electrons B. 138 protons and 88 neutrons c. 226 neutrons and 138 electrons D. 138 neutrons and 88 protons | 12 |

584 | A neutron of energy 1 Me ( V ) and mass ( 1.6 times 10^{-27} ) kg passes a proton at such a distance that the angular momentum of the neutron relative to the proton approximately equals ( 10^{-33} mathrm{J} ) s. The distance of closest approach neglecting the interaction between particles is A. ( 0.44 n m ) B. ( 0.44 m m ) c. ( 0.44^{circ} ) D. ( 0.44 f m ) | 12 |

585 | In hydrogen atom, an electron makes transition from ( n=3 ) to ( n=2 ) state in time interval of ( 1.2 times 10^{-8} ) s. Calculate the average torque (in ( mathrm{Nm} ) ) acting on the electron during this transition. A . ( 1.055 times 10^{-26} ) В. ( 4.40 times 10^{-27} ) c. ( 1.7 times 10^{-26} ) D. ( 8.79 times 10^{-27} ) | 12 |

586 | Identify which of the following is the smallest discrete value of electromagnetic energy? A. photon B. proton c. electron D. neutron E. quark | 12 |

587 | A neutron of energy 1 Me ( V ) and mass ( 1.6 times 10^{-27} ) kg passes a proton at such a distance that the angular momentum of the neutron relative to the proton approximately equals ( 10^{-33} mathrm{J} ) s. The distance of closest approach neglecting the interaction between particles is A. ( 0.44 n m ) B. ( 0.44 m m ) c. ( 0.44^{circ} ) D. ( 0.44 f m ) | 12 |

588 | State the postulates of Bohr atom model. Obtain the expression for the radius of the ( n^{t h} ) orbit of an electron based on Bohr’s theory. | 12 |

589 | The energy levels of an atom of a certain element are shown in the given figure 5 Which one of the transitions ( A, B, C, D ) or E will result in the emission of photons of electromagnetic radiation of wavelength 618.75 nm? Support your answer with mathematical calculations. | 12 |

590 | A sample of hydrogen gas contain 100 atoms. All the atoms are excited to the same n excited state. The energy released by all the atoms is ( frac{4800}{49} . R= ) ( 13.6 mathrm{eV} ) ), as they come to the ground state through various types of transition Then Find A. maximum energy of the emitted photon will be less ( operatorname{than} frac{48}{49} R c h ) B. Maximum energy of the emitted photon may be greater than ( frac{48}{49} ) Rch c. The value of ( n=6 ) D. None of these | 12 |

591 | A positive ion having only one electron ejects it if a photon of ( gamma leq 228 A^{0} ) is abosrbed by it. The ion is A ( . H e^{+} ) B. ( L i^{+} ) ( mathbf{c} cdot B e^{+3} ) D. ( B^{+4} ) | 12 |

592 | With the increase in quantum number the energy difference between consecutive energy levels A. remains constant B. decreases. c. increases D. sometimes increases sometimes decreases | 12 |

593 | The KE of the electron in an orbit of radius ‘r’ in hydrogen atom is proportional to (e=electronic charge) ( ^{A} cdot frac{e^{2}}{r^{2}} ) B. ( frac{e^{2}}{2 r^{3}} ) c. ( frac{e^{2}}{r} ) D. ( frac{e^{2}}{2 r^{2}} ) | 12 |

594 | According to Rutherford atom model, the spectrum emitted by an atom is : A. Line spectrum B. Continuous spectrum c. continuous absorption spectrum D. Band spectrum | 12 |

595 | Let the potential energy of a hydrogen atom in the ground state be zero. Then its energy in the first excited state will be A. 10.2 eV в. 13.6 еV c. 23.8 eV D. ( 27.2 mathrm{eV} ) | 12 |

596 | The electrons in the atom of an element which determine its chemical and electrical properties are. A. Valence electrons B. Revolving electrons c. Excess electrons D. Active electrons | 12 |

597 | What conclusion was drawn by Rutherford based on Geiger-Marsden’s experiment on scattering of alpha particles? | 12 |

598 | An electron in hydrogen atom after absorbing an energy photon jumps from energy state ( n_{1} ) to ( n_{2} ). Then it returns to ground state after emitting six different wavelengths in emission spectrum. The energy of emitted photons is either equal to less than the absorbed photons. The ( n_{1} ) and ( n_{2} ) are A ( . n_{2}=4, n_{1}=3 ) в. ( n_{2}=5, n_{1}=3 ) c. ( n_{2}=4, n_{1}=1 ) D. ( n_{2}=5, n_{1}=1 ) | 12 |

599 | The visible region of hydrogen spectrum was first studied by A. Lyman B. Balmer c. Pfund D. Brackett | 12 |

600 | The mean momentum of a nucleon in a nucleus with mass number ( A ) varies as ( mathbf{A} cdot A^{3} ) B. ( A^{2} ) ( c cdot frac{2}{3} ) D. E ( cdot frac{1}{3} ) | 12 |

601 | State the postulate of Bohr’s theory regarding emission off a photon | 12 |

602 | The ratio of radii of first orbit of hydrogen atom and the second orbit of singly ionised helium atom will be A . 1: 2 B . 4: 1 c. 1: 4 D. 8: 1 | 12 |

603 | This particle balances the charges from the protons to make the atom neutral- A. neutron B. electron c. nucleus D. none of these | 12 |

604 | Why are the “deflections caused by an aluminum foil less than that of gold foil in an ( alpha ) -ray scattering experiment. Can these deflections be changed by changing the kinetic energy of ( alpha ) particles”. | 12 |

605 | Suppose a particle ( a ) of charge ( 2 e ) and ( operatorname{mass} 2 m_{e}left(m_{e} ) being mass of electron) right. revolves around the proton in nearest allowed circular orbit of radius r. If the radius of first Bohr orbit for the electron is ( A_{0}, ) then the relation between ( r ) and ( a_{0} ) is A. ( a_{0}=4 r ) ( r ) B . ( a_{0}=8 r ) c. ( a_{0}=2 r ) D. ( a_{0}=frac{r}{4} ) | 12 |

606 | Energy levels I, II, Ill of a certain atom correspond to increasing values of energy i.e., ( boldsymbol{E}_{boldsymbol{I}}<boldsymbol{E}_{boldsymbol{I I}}<boldsymbol{E}_{boldsymbol{I I I}} . ) If ( boldsymbol{lambda}_{1}, boldsymbol{lambda}_{2}, boldsymbol{lambda}_{3} ) be the wavelengths of radiations corresponding to the transitions III to II II to I and III to I respectively, which of the following relations is correct? A. ( lambda_{1}=lambda_{2}+lambda_{3} ) B. ( lambda_{3}=frac{lambda lambda_{2}}{lambda_{1}+2_{2}} ) c. ( lambda_{1}+lambda_{2}+lambda_{3}=0 ) D ( cdot lambda frac{2}{3}=lambda_{1}^{2}+lambda frac{2}{2} ) | 12 |

607 | The minimum energy to ionize an atom is also the energy required to: A. add one electron to the atom B. excite the atom from its ground state to its first excited state C. remove one outermost electron from the atom D. remove one innermost electron from the atom | 12 |

608 | Let ( A_{n} ) be the area enclosed by the ( n^{t h} ) orbit in a hydrogen atom. The graph of ( ln left(A_{n} / A_{l}right) ) against ( ln (n) ) This question has multiple correct options A. Will pass through origin B. Will be a straight line with slope 4 c. will be monotonically increasing nonlinear curve D. will be circle | 12 |

609 | If the radius of a nucleus with mass number 125 is 1.5 Fermi, then radius of a nucleus with mass number 64 is A . 0.48 Fermi B. 0.96 Fermi c. 1.92 Fermi D. 1.2 Fermi | 12 |

610 | In Bohr’s model of hydrogen atom, let ( P E ) represent potential energy and ( T E ) the total energy. In going to a higher orbit, A. ( P E ) increases, ( T E ) decreases B. ( P E ) decreases, ( T E ) increases c. ( P E ) increases, ( T E ) increases D. ( P E ) decreases, ( T E ) decreases | 12 |

611 | The ratio of specific charges of an electron to that of a hydrogen ion is? A .2: 1 B. 1: 1 c. 1: 1840 D. 1840: 1 | 12 |

612 | A diatomic molecule has moment of inertia ( I . ) By Bohrs quantization condition its rotational energy in the ( n^{t h} ) level ( (n=0 ) is not allowed) is A ( cdot frac{1}{n^{2}}left(frac{mathrm{h}^{2}}{8 pi^{2} mathrm{I}}right) ) B. ( frac{1}{mathrm{n}}left(frac{mathrm{h}^{2}}{8 pi^{2} mathrm{I}}right) ) ( ^{c} cdotleft(frac{h^{2}}{8 pi^{2} I}right) ) D. ( _{mathrm{n}^{2}}left(frac{mathrm{h}^{2}}{8 pi^{2} mathrm{I}}right) ) | 12 |

613 | Two photons having A. Equal wavelengths have equal linear momenta B. Equal energies have equal linear momenta C. Equal frequencies have equal linear momenta D. Equal linear momenta have equal wavelengths | 12 |

614 | According to drop model of nucleus which of the following cannot be explained? A. Fission B. Fusion D. All of these | 12 |

615 | The distance of the closest approach of an alpha particle fired at a nucleus with kinetic energy ( boldsymbol{K} ) is ( boldsymbol{r}_{0} . ) The distance of the closest approach when the ( alpha ) particle is fired at the same nucleus with kinetic energy ( 2 K ) will be A ( .4 r_{n} ) B. ( frac{r_{0}}{2} ) c. ( frac{r_{0}}{4} ) D. ( 2 r_{0} ) | 12 |

616 | 17. If the radius of an orbit is r and the velocity of electron in it is v, then the frequency of electron in the orbit will be 210 (a) 2nry (b) vr vr V (c) 2 (d) – 270 21tr | 12 |

617 | In Thomson experiment of finding ( frac{e}{m} ) for electrons, beam of electrons is replaced by that of muons (particle with same charge as of electrons but mass 208 times that of electrons). No deflection condition in this is case | 12 |

618 | The ratio of kinetic energy and the total energy of the electron in the nth quantum state of Bohr’s atomic model of hydrogen atom is A . -2 B. – 1 ( c cdot+2 ) D. +1 | 12 |

619 | Name the phenomenon which shows the quantum nature of electromagnetic radiation. | 12 |

620 | An electron is in an excited state in a hydrogen like atom. It has a total energy -3.4eV. The kinetic energy of the electron is E and its de Broglie wavelength is ( lambda ) A. ( E=6.8 e V, lambda=6.6 times 10^{-10} m ) B . ( E=3.4 e V, lambda=6.6 times 10^{-10} m ) C . ( E=3.4 e V, lambda=6.6 times 10^{-11} mathrm{m} ) D. ( E=6.8 e V, lambda=6.6 times 10^{-11} m ) | 12 |

621 | Energy of electron is an orbit of H-atom is A. Positive B. Zero c. Negative D. Unity | 12 |

622 | The order of size of nucleus and Bohr’s radius of an atom respectively are: ( mathbf{A} cdot 10^{-14} m, 10^{-10} m ) В. ( 10^{-10} m, 10^{-8} m ) c. ( 10^{-20} m, 10^{-16} m ) D. ( 10^{-8} m, 10^{-6} m ) | 12 |

623 | Assertion Balmer series lies in the visible region of electromagnetic spectrum. Reason ( frac{1}{lambda}=Rleft[frac{1}{2^{2}}-frac{1}{n^{2}}right], ) where ( n=3,4,5 ) A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion c. Assertion is correct but Reason is incorrect D. Assertion is incorrect but Reason is correct | 12 |

624 | Calculate energy in kcal/mole necessary to remove an electron in a hydrogen atom in fourth principal quantum number to infinity. | 12 |

625 | Number of visible lines in Balmer series. A . 2 B. 4 ( c .3 ) ( D ) | 12 |

626 | An ( alpha ) – particle travels in a circular path of radius ( 0.45 mathrm{m} ) in a magnitude field ( mathrm{B} ) ( =1.2 mathrm{Wb} / mathrm{m}^{2} ) with a speed of ( 2.6 times 10^{7} ) ( mathrm{m} / mathrm{s} . ) The period of revolution of the ( alpha ) particle is: B . (b) 1.1 ( times 10^{-6} ) s c. ( left(text { с ) } 1.1 times 10^{-7} ) s right. D. (d) 1.1 ( times 10^{8} ) s | 12 |

627 | According to JJ Thomson model,Electrons in atom are A. revolving around nucleus B. embeded in nucleus c. static around the nucleus D. none of these | 12 |

628 | Draw a neat labelled energy level diagram of the Hydrogen atom. | 12 |

629 | On the basis of following features identify the correct option: These rays travel in straight line. These rays consist of positively charged particles. These rays are deflected by electric and magnetic fields. ( mathrm{e} / mathrm{m} ) values for the particles are not same | 12 |

630 | Complete the following: Mass ( = ) ( times ) density A. Volume B. Area c. width D. Density | 12 |

631 | The Rydberg constant for Hydrogen is ( 1.097 times 10^{7} m^{-1} . ) Calculate the short wavelength limit of Lyman series. | 12 |

632 | In order to excite an electron from ( n= ) 2 to ( n=4 ) the atom needs to A. release heat B. release a photon. c. maintain a constant energy. D. release energy. E. absorb energy. | 12 |

633 | Which of the following was not a conclusion of Rutherford’s gold foil experiment? A. The atom is mainly empty space. B. The nucleus has a negative charge c. The atom has a dense nucleus. D. Alpha particles can pass through a thin sheet of gold foil E. All of the above are correct regarding the gold foil experiment. | 12 |

634 | Name the phenomenon which shows the quantum nature of electromagnetic radiation. | 12 |

635 | For the following statements, write T for True and ( F ) for False. The mass of an electron is ( 1 / 2000 ) times that of proton. | 12 |

636 | The photoelectric effect was experimentally studied by A. Einstein B. Lennard c. Hertz D. Rutherford | 12 |

637 | An atom is initially at an energy level ( boldsymbol{E}=-mathbf{6 . 5 2} e boldsymbol{V} . ) It absorbs a photon of wavelength ( 860 n m . ) The internal energy of atom after absorbing photon is A . ( 5.08 e V ) B. ( 1.44 e V ) c. ( -1.44 e V ) D. ( -5.08 e V ) | 12 |

638 | The first excitation potential energy or the minimum energy required to excite the atom from ground state of hydrogen atom is A. 13.6 eV B. 10.2 eV c. ( 3.4 e V ) D. ( 1.89 mathrm{eV} ) | 12 |

639 | A photon of wavelength 300 nm interacts with a stationary hydrogen atom in ground state. During the interaction, whole energy of the photon is transferred to the electron of the atom. State which possibility is correct. (consider, Planck’s constant ( =4.1 times ) ( 10^{-15} e V s, ) velocity of light ( =3 x ) ( 10^{8} m / s, ) ionisation energy of hydrogen ( =13.6 mathrm{eV} ) A. Electron will be knocked out of the atom B. Electron will go to any excited state of the atom C. Electron will go only to first excited state of the atom D. Electron will keep orbiting on the ground state of the atom | 12 |

640 | Who is known as the father of nuclear physics? A. Ernest Rutherford B. Dalton c. J.J. Thomson D. E. Goldstein | 12 |

641 | The ( alpha ) -particles with initial kinetic energy 4.8 mev are shot at gold atoms ( (z=79) . ) The potential of ( alpha ) -particle at the closest distance to the gold nucleus is A ( .4 .8 M V ) в. zero ( mathrm{c} .9 .6 mathrm{MV} ) D. 2.4MV | 12 |

642 | The radius of an atom is of the order of: A ( cdot 10^{-12} mathrm{cm} ) B . ( 10^{-14} mathrm{cm} ) ( c cdot 10^{-10} mathrm{cm} ) ( D cdot 10^{-8} mathrm{cm} ) | 12 |

643 | 238 92 ( mathrm{U} ) atom disintegrates to ( ^{214} 84 P mathrm{o} ) with a half life of ( 4.5 times 10^{9+} ) years by emitting six alpha particle and ( n ) electrons. Here n is ( A cdot 6 ) B. 4 ( c cdot 10 ) D. | 12 |

644 | The value of wavelength of radiation emitted due to transition of electrons from ( n=4 ) to ( n=2 ) state in hydrogen atom will be A ( cdot frac{5 R}{36} ) в. ( frac{16}{3 R} ) c. ( frac{36}{5 R} ) D. ( frac{3 R}{16} ) | 12 |

645 | Consider a positronium atom consisting of a positron and an electron each having mass ( m ) (equal to mass of electron) in the orbit around its centre of mass. This structure lasts for ( 10^{-6} s ) only. Find the energy levels for this model. | 12 |

646 | Cathode rays have velocities A. Equal to that of light B. Greater than that of light C. Less than that of light D. Greater than that of matter waves | 12 |

647 | A substance consisting of atoms which all have the same number of protons is called a/an A. Element B. Molecule c. Mixture D. Solution | 12 |

648 | Both the nucleus and the atom of some element are in their respective first excited states. They get de-excited by emitting photons of wavelengths ( boldsymbol{lambda}_{N}, boldsymbol{lambda}_{boldsymbol{A}} ) respectively. The ratio ( frac{lambda_{N}}{lambda_{A}} ) is closest to: A ( cdot 10^{-6} ) B . 10 ( c cdot 10^{-1} ) D. ( 10^{-10} ) | 12 |

649 | What is ionization potential of an atom? | 12 |

650 | Two parallel plates ( 5 mathrm{cm} ) apart are connected to a 500 V D.C supply. Assuming that an electron starts from rest, its velocity after a nano second is A ( cdot 1.56 times 10^{6} m / s ) В . ( 1.66 times 10^{6} mathrm{m} / mathrm{s} ) c. ( 1.76 times 10^{6} m / s ) D. ( 1.86 times 10^{6} mathrm{m} / mathrm{s} ) | 12 |

651 | When a hydrogen atom is raised from ground energy level to excited energy level, then A. potential energy increases and kinetic energy decreases B. kinetic energy increases and potential energy decreases c. Both KE and PE increase D. Both KE and PE decrease | 12 |

652 | ( mathrm{Na}^{oplus} ) and Ne are ( _{-1-} ldots_{-} ) to each other. A. isotopes B. isoelectronic ( c . ) isobars D. allotropic | 12 |

653 | Assertion In Rutherford’s gold foil experiment very few ( boldsymbol{alpha} ) – particles are deflected back. Reason Nucleus present inside the atom is heavy. | 12 |

654 | The e/m ratio of anode rays is constant irrespective of the gas filled inside the discharge tube A. True B. False | 12 |

655 | An ( alpha- ) particle having energy ( 10 M e V ) collides with a nucleus of atomic number 50.Then distance of closet approach will be A ( cdot 14.4 times 10^{-16} m ) в. ( 1.7 times 10^{-7} mathrm{m} ) c. ( 1.5 times 10^{-12} m ) D. ( 14.4 times 10^{-15} mathrm{m} ) | 12 |

656 | The diagram shows the energy levels for an electron in a certain atom. Which transition shown represents the emission of a photon with the most energy? ( A cdot I ) в. ( I I ) c. ( I I I ) D. ( I V ) | 12 |

657 | The electric potential between a proton and an electron is given by ( boldsymbol{V}= ) ( mathbf{V}_{0} ln frac{mathbf{r}}{mathbf{r}_{0}}, ) where ( mathbf{r}_{0} ) is a constant Assuming Bohr’s model to be applicable, write variation of ( mathbf{r}_{mathbf{n}} ) with ( mathbf{n}, mathbf{n} ) being the principal quantum number? ( A cdot r_{n} propto n ) в . ( mathrm{r}_{mathrm{n}} propto 1 / mathrm{n} ) ( c cdot r_{n} propto n^{2} ) D. ( mathrm{r}_{mathrm{n}} propto 1 / mathrm{n}^{2} ) | 12 |

658 | The maximum number of electrons in a shell is A ( cdot n^{2} ) B ( cdot 2 n^{2} ) ( c cdot 2 n ) D. ( n ) | 12 |

659 | The ratio of mass densities of nuclei of ( ^{40} mathrm{Ca} ) and ( ^{16} mathrm{O} ) is close to: ( mathbf{A} cdot mathbf{1} ) B. 2 ( c .0 . ) D. 5 | 12 |

660 | The unit of length convenient on the nuclear scale is a fermi : ( 1 mathrm{f}=10^{-15} mathrm{m} ) Nuclear sizes obey roughly the following empirical relation ( : r=r_{0} A^{1 / 3} ) where, ( r ) is the radius of the nucleus, ( A ) its mass number, and ( r_{o} ) is a constant equal to about ( 1.2 mathrm{f} ). Show that the rule implies that nuclear mass density is nearly constant for different nuclei Estimate the mass density of sodium nucleus. | 12 |

661 | What initial kinetic energy (in joule and in ( M e V ) ) did the ( alpha ) – particle have? A . 36.3 B. 0.36 c. 3.63 D. 2.63 | 12 |

662 | JJ Thomson discovered which subatomic particle? A. protron B. electron c. neutron D. nucleus | 12 |

663 | (a) Using Bohr’s second postulate of quantization of orbital angular momentum show that the circumference of the electron in the ( n^{t h} ) orbital state in hydrogen atom is ( n ) times the de Broglie wavelength associated with it. (b) The electron in hydrogen atom in initially in the third excited state.What is the maximum number of spectral lines which can be emitted.When it finally moves to the ground state? | 12 |

664 | Discovery of the nucleus of an atom was due to the experiment carried out by: A. Bohr B. Rutherford c. moseley D. Thomson | 12 |

665 | A diatomic molecule is made of two masses ( m_{1} ) and ( m_{2} ) which are separated by a distance ( r . ) If we calculate its rotational energy by applying Bohr’s rule of angular momentum,its energy will be given by ( n ) is an integer) A ( cdot frac{left(m_{1}+m_{2}right)^{2} n^{2} h^{2}}{2 m_{1}^{2} m_{2}^{2} r^{2}} ) В ( cdot frac{n^{2} h^{2}}{2left(m_{1}+m_{2}right) r^{2}} ) c. ( frac{2 n^{2} h^{2}}{left(m_{1}+m_{2}right) r^{2}} ) D. ( frac{left(m_{1}+m_{2}right) n^{2} h^{2}}{2 m_{1} m_{2} r^{2}} ) | 12 |

666 | The visible region of hydrogen spectrum was first studied by A. Lyman B. Balmer c. Pfund | 12 |

667 | Give the main postulates of Bohr’s model of an atom. | 12 |

668 | An electron with kinetic energy ( 5 e V ) is incident on a hydrogen atom in its ground state. The collision A. must be elastic B. may be partially elastic c. must be completely inelastic D. may be completely inelastic | 12 |

669 | In Rutherford experiment, a 5.3 MeV ( alpha- ) particle moves towards the gold nucleus ( (Z=79) . ) How close does the ( alpha- ) particle to get the centre of the nucleus,before it comes momentarily to rest and reverses its motion? ( left(boldsymbol{E}_{mathbf{0}}=right. ) ( left.mathbf{8 . 0} times mathbf{1 0}^{-mathbf{1 2}} mathbf{F} / boldsymbol{m}right) ) A ( cdot 3.4 times 10^{-15} mathrm{m} ) B. ( 8.6 times 10^{-14} ) m c. ( 4.3 times 10^{-14} ) и D. ( 1.6 times 10^{-14} mathrm{m} ) | 12 |

670 | Rutherford’s alpha scattering experiment showed for the first time that the atom has: A . electrons B. protons c. nucleus D. neutrons | 12 |

671 | According to Rutherford’s ( alpha ) -scattering experiment, which of the following is the INCORRECT conclusion? A. There is a large space between the nucleus of the atom and the electrons B. The electrons orbit the nucleus of the atom. C . The nucleus is positively charged. D. The atom is neutral. E. Electrons can change orbits when they absorb or emit energy. | 12 |

672 | the anode is kept at positive potential with respect to the cathode. A. themions are get attracted towards the anode and accelerate towards the anode B. themions are get deviated towards the anode and accelerate towards the anode C. themions get attracted towards the cathode and accelerate towards the cathode D. none of these | 12 |

673 | Packets of which of the following quantity best describe photons? A. energy B. mass c. volume D. power E. waves | 12 |

674 | The ionisation energy for excited hydrogen atom in ( e V ) will be A . 13.6 B. less than 13.6 c. greater than 13.6 D. 3.4 or less | 12 |

675 | Energy required for the electron excitation in ( mathrm{Li}^{+} ) from the first to the third Bohr orbit is A. ( 12.1 mathrm{eV} ) B. 36.3 eV c. ( 108.8 mathrm{eV} ) D. ( 122.4 mathrm{eV} ) | 12 |

676 | ILLUSTRATION 29.1 The electron in a hydrogen atom makes a transition ni →n2, where n, and n are the principal quantum numbers of the two energy states. Assume Bohr’s model to be valid.The time period of the electron in the initial state is eight times that in the final state. What are the possible values of n and n? | 12 |

677 | The photoelectric effect represent that A . Light has a particle nature B. Electron has a wave nature c. Proton has a wave nature D. None of the above | 12 |

678 | A beam of alpha-particles is fires at a piece of gold foil as shown below. After striking the gold foil, in which direction do most of the alpha-particles travel? ( A cdot P ) в. ( Q ) ( c . R ) D. | 12 |

679 | Let ( m_{P} ) be the mass of a proton, ( m_{n} ) the mass of a neutron, ( M_{1} ) the mass of a ( 20 mathrm{Ne} ) nucleus and ( M_{2} ) the mass of a 10 ( _{20}^{40} C a ) nucleus. Then This question has multiple correct options A. ( M_{2}=2 M_{1} ) В . ( M_{2}>2 M_{1} ) c. ( M_{2}<2 M_{1} ) D. ( M_{1}<10left(m_{n}+m_{p}right) ) | 12 |

680 | If the velocity of electron in the first Bhors orbit of H atoms is ( s 2.19 times ) ( 10^{6} m / s . ) calculate the velocity of electron in Bohrs second orbit? | 12 |

681 | Rutherford experiment of scattering of ( alpha ) -particles shows for the first time that the atom has: A. proton B. nucleus c. electron D. neutron | 12 |

682 | Doubly ionised Helium atoms and Hydrogen ions are accelerated from rest through the same potential drop. The ratio of the final velocities of the Helium and the Hydrogen ions is ( A cdot 2 ) B. ( sqrt{2} ) ( c cdot 1 / 2 ) D. ( 1 / sqrt{2} ) | 12 |

683 | How can the rate of emission of electrons in a cathode ray tube can be increased? A. Increasing resistance of filament B. Increasing filament current c. Decreasing filament current D. Increasing magnetic field inside tube | 12 |

684 | The ionisation potential of ( boldsymbol{H} ) -atom is ( 13.6 V . ) When it is excited from ground state by monochromatic radiations of ( $ $ 970.6 / ) buildrel ( _{-} ) lcirc lover ( mathrm{~ I l m a t h r m { A } 3 $ $ , ~ t h e ~ n u m b e r ~ o f ~} ) emission lines will be (according to Bohr’s theory) A . 10 B. 8 c. 6 ( D ) | 12 |

685 | The p.d. at the ends of a cathode ray tube is increased to 9 times its original potential difference Then I. The velocity of cathode rays increases to …. times II. The energy of cathode rays increases to…. times A . 9,3 в. 9.9 ( c .3 .9 ) D. 3,3 | 12 |

686 | Explain emission and absorption spectra | 12 |

687 | What is the effective mass of photon having wavelength ( lambda ? ) | 12 |

688 | White light is passed through sodium vapours contained in a thin walled glass flask and the transmitted light is examined with the help of a spectrometer. The spectrum so obtained is. A. Absorption spectrum B. Solar spectrum c. Band spectrum D. Continuous spectrum | 12 |

689 | In Thomson’s experiment, prove that the ratio of charge to the mass ( (e / m) ) of an electron is given by: ( frac{e}{m}=frac{1}{2 V} cdot frac{E^{2}}{B^{2}} ) where the terms have their usual meaning | 12 |

690 | An electron of a stationary hydrogen atom passes from the fifth energy level to the ground level. The velocity that the atom acquired as a result of photon emission will be: A ( cdot frac{25 m}{24 h R} ) B . ( frac{24 m}{24 h R} ) ( mathrm{c} cdot frac{24 h R}{25 m} ) D. ( frac{25 m}{14 h R} ) | 12 |

691 | The potential energy of an electron in the fifth orbit of hydrogen atom is A. 0.54 eV B. -0.54 eV c. 1.08 eV D. ( -1.08 mathrm{eV} ) | 12 |

692 | A hydrogen atom of mass ‘ ( m^{prime} ) being at rest, makes a transition from its first excited state to ground state. As a result a photon of wavelength ( ^{prime} lambda^{prime} ) is emitted and the hydrogen atom recoils. If ( ^{prime} boldsymbol{E}_{0}^{prime} ) is the ionization energy of ( mathbf{a} ) hydrogen atom, the Planck’s constant is ( h ) and ( c ) is the speed of light in vacuum, the recoil speed is This question has multiple correct options A ( cdot frac{3 E_{0}}{4 m_{c}} ) в. ( frac{3 E_{0}}{m c} ) c. ( frac{h}{2 m lambda} ) D. ( frac{h}{m lambda} ) | 12 |

693 | If the nuclear radius of ( ^{27} A l ) is 3.6 Fermi, the approximate nuclear radius of ( ^{64} mathrm{Cu} ) in Fermi is A . 4.8 в. 3.6 ( c .2 .4 ) D. 1. | 12 |

694 | The number of neutrons in ( _{92} U^{235} ) nucleus is: A . 327 в. 235 c. 143 D. 92 | 12 |

695 | The period of revolution of an electron in the ground state of hydrogen atom is ( T ) The period of revolution of the electron in the first excited state is? A . 2 न в. 4 न ( c .6 ) न D. 8 T | 12 |

696 | Describe in brief what is observed when moving electrons are allowed to fall on a thin graphite film and the emergent beam falls on a fluorescent screen. | 12 |

697 | State True or False. Nucleus always contains proton. A. True B. False | 12 |

698 | Diagram shows an electron gun inside cathode ray tube. Label the screen with the letter ( S ). | 12 |

699 | State Bohr’s postulate of hydrogen atom which successfully explains the emission lines in the spectrum of hydrogen atom. Use Rydberg formula to determine the wavelength of ( boldsymbol{H}_{boldsymbol{alpha}} ) line. [Given: Rydberg constant ( boldsymbol{R}= ) ( 1.0310^{7} m^{-1} ) | 12 |

700 | Explain the spectral series of hydrogen atom (diagram not necessary) | 12 |

701 | What would be the radius of second orbit of ( boldsymbol{H} boldsymbol{e}^{+} ) ion? A . ( 1.058 AA ) в. ( 3.023 AA ) c. ( 2.068 hat{h} ) D. ( 4.458 dot{h} ) | 12 |

702 | The wavelength of ( H_{alpha} ) line in hydrogen spectrum was found to be ( 6563 A ) in the laboratory. If the wavelength of same line in the spectrum of a milky way is ( boldsymbol{O} ) observed to be ( 6568 A ), then recession velocity of milky way will be A. ( 105 mathrm{m} / mathrm{s} ) В. ( 1.05 times 10^{6} mathrm{m} / mathrm{s} ) c. ( 10.5 times 10^{6} mathrm{m} / mathrm{s} ) D. ( 0.105 times 10^{6} mathrm{m} / mathrm{s} ) | 12 |

703 | Explain emission and absorption spectra | 12 |

704 | 34. Hydrogen (H’), Deuterium (HP), singly ionised Helium (zHe“)+ and doubly ionised lithium (zLiº)++ all have one electron around the nucleus. Consider an electron transition from n = 2 to n = 1. If the wave lengths of emitted radiation are 21, I, 23 and 24 respectively then approximately which one of the following is correct? (a) 11 = 2z = 413 = 984 (b) 2= 222 = 32z = 424 (c) 427 = 22, = 223 = 14(d) 2, = 22, = 3/3 = 24 (JEE Main 2014) | 12 |

705 | The rest mass of a photon is A. zero B . ( 1.6 times 10^{-19} mathrm{kg} ) c. ( 3.1 times 10^{-30} mathrm{kg} ) D. ( 9.1 times 10^{-31} mathrm{kg} ) | 12 |

706 | The presence of nucleus in an atom is determined by Rutherford ( boldsymbol{alpha}-boldsymbol{r} boldsymbol{a} boldsymbol{y} ) scattering experiment. A. True B. False | 12 |

707 | A cathode ray tube has a potential difference of ( V ) volt between the cathode and the anode. The speed of cathode rays is given by ( mathbf{A} cdot 6 times 10^{-5} sqrt{V} mathrm{cm} / mathrm{s} ) B . ( 6 times 10^{5} sqrt{V} mathrm{m} / mathrm{s} ) ( mathbf{c} cdot 6 times 10^{7} sqrt{V} mathrm{cm} / mathrm{s} ) D ( cdot 6 times 10^{3} sqrt{V} m / s ) | 12 |

708 | In a vacuum diode, the space around the cathode which is filled with electrons, is called A. space charge B. electric field c. magnetic field D. electron cloud | 12 |

709 | An incandescent filament emits a spectrum which is : A. line spectrumm B. band spectrum c. continuous spectrum D. characteristic spectrum | 12 |

710 | Identify the principal quantum number for the last electron that is added to sodium? A. B. 2 ( c cdot 3 ) D. 5 E. 4 | 12 |

711 | Hydrogen atoms are excited from ground state to the state of principal quantum number 4. Then, the number of spectral lines observed will be A . 3 B. 6 ( c .5 ) ( D ) | 12 |

712 | Using Rutherford model of the atom, derive the expression for the tota energy of the electron in hydrogen atom What is the significance of total negative energy possessed by the electron? | 12 |

713 | The distance of closest approach of an ( alpha ) – particle fired towards a nucleus with momentum ( p ),is ( r . ) The distance of closest approach when the momentum of ( alpha ) -particle is ( 2 p ) is A ( cdot 2 r ) B. ( 4 r ) ( c cdot r / 2 ) D. ( r / 4 ) | 12 |

714 | Which of the following statement is true on a scattering of atom according to Rutherfords experiments on the alpha particle ? A. Atoms are roughly spherical with a radius of about ( 10^{-10} m ) B. The electrons occupy quantized energy levels absorbing or emitting energy only when they make a quantum jump between these levels c. The density of positive charge within an atom is not uniform throughout the atoms volume D. Allowed electron orbits must have a circumference equal to a whole number times the electrons de Broglie wavelength E. Alpha particles are positively charged | 12 |

715 | In which of the following systems will the radius of the first orbit ( (n=1) ) be minimum? A. Doubly ionized lithium B. singly ionized helium c. Deuterium atom D. Hydrogen atom | 12 |

716 | The distance of the closest approach of an alpha particle fired at a nucleus with kinetic energy ( boldsymbol{K} ) is ( boldsymbol{r}_{0} . ) The distance of the closest approach when the ( alpha ) particle is fired at the same nucleus with kinetic energy ( 2 K ) will be ( ^{A} cdot frac{r_{0}}{2} ) B. ( 4 r_{0} ) c. ( frac{r_{0}}{4} ) D. ( 2 r_{0} ) | 12 |

717 | In the Bohr Model of a hydrogen atom, the centripetal force is furnished by the Coulomb attraction between the proton and the electron. If ( a_{o} ) is the radius of the ground state orbit, ( m ) is the mass, and ( e ) is the charge on the electron, and ( epsilon_{o} ) is the permittivity of vacuum, then the speed of the electron is: A . 0 в. ( frac{e}{sqrt{epsilon_{o} a_{o}}} ) c. ( frac{e}{sqrt{4 pi epsilon_{c} a_{o} m}} ) D. ( sqrt{frac{4 pi epsilon_{o} a_{o} m}{e}} ) | 12 |

718 | If an element has 22 electrons then what will be its atomic number? A . 10 B. 25 c. 15 D. 22 | 12 |

719 | A certain metallic surface is illuminated with monochromatic.light of wavelength ( lambda ) The stopping potential for photo electric .current for this light is ( 3 v lambda ) if the same surface is illuminated with light of wavelength 2 ( lambda ) the stopping potential is ( v_{0} . ) The threshold wavelength for this surface for photo-electric is A ( .4 lambda ) B. ( 5 lambda ) c. ( 6 lambda ) D. ( 7 lambda ) | 12 |

720 | There are only three hydrogen atoms in a discharge tube. The analysis of spectrum shows that in all the hydrogen atoms, electrons are de-exciting from the fourth orbit. What should be the maximum number of spectral lines? ( A cdot 6 ) B. 1 ( c cdot 4 ) D. 5 | 12 |

721 | List out any two limitations of Bohr atom model. | 12 |

722 | In the figure six lines of emission spectrum are shown. Which of them will be absent in the absorbtion spectrum. A ( cdot 1,2,3 ) в. 1,4,6 ( c cdot 4,5,6 ) D. 1,2,3,4,5,6 | 12 |

723 | The angular momentum of the electron in hydrogen atom in the ground state is ( mathbf{A} cdot 2 h ) в. ( frac{h}{2} ) c. ( frac{h}{2 pi} ) D. ( frac{h}{4 pi} ) | 12 |

724 | Magnetic field at the center (at nucleus) of the hydrogen-like atoms (atomic number ( =Z ) ) due to the motion of electron in ( n^{t h} ) orbit is proportional to A ( cdot frac{n^{3}}{z^{5}} ) B. ( frac{n^{4}}{z} ) c. ( frac{z^{2}}{n^{3}} ) D. ( frac{z^{3}}{n^{5}} ) | 12 |

725 | In the Geiger-Marsden experiment, the force that scatters particles is A. nuclear force B. coulomb force c. both A and B D. gravitational force | 12 |

726 | With the increase in quantum number the energy difference between consecutive energy levels A. remains constant B. decreases c. increases D. sometimes increases sometimes decreases | 12 |

727 | 9. If the binding energy of the electron in hydrogen atoms is 13.6 eV, the energy required to remove the electron from the first excited state of Liis (a) 122.4 eV (b) 30.6 eV (c) 13.6 eV (d) 3.4 eV (AIEEE 2003) 10 Annelang is dicintegrated into two nuclear narts ha | 12 |

728 | One atomic mass unit (a.m.u) is equal to: A ( .2 .67377 times 10^{-27} ) В. ( 1.67377 times 10^{-22} ) c. ( 0.67377 times 10^{-27} ) D. ( 1.67377 times 10^{-27} ) | 12 |

729 | A hydrogen atom is excited from ( n=1 ) to ( n=3 ) state. The amount of energy absorbed by the atom will be A . ( 12.1 e V ) B. ( 25 e V ) c. ( 13.6 e V ) D. ( -13.6 e V ) | 12 |

730 | The photoelectric effect proves that light consists of: A. Photons B. Electrons c. Electromagnetic waves D. Mechanical waves | 12 |

731 | What is the wavelength of light emitted when the electron in hydrogen atom undergoes transition from an energy level with ( n=4 ) to an energy level with ( n=2 ) ? What is the colour of the radiation? | 12 |

732 | In an experiment on the photo-electric effect, singly ionized helium is excited electronically to different energy levels. The light emitted by ionized helium is incident on a photo-electric plate in a photocell. When helium is excited to fourth energy level, then the observed stopping potential of the photocell is found to be five times the stopping potential measured when the photoelectrons are produced by using light emitted by hydrogen atom, excited to the third energy level. Determine the work function of the material of the photo-electric plate. | 12 |

733 | Schrodinger wave equation 2. Heisenberg uncertainty principle 3. Millikan oil drop experiment 4. Chadwick’s discovery of neutron Of the scientific milesiones listed above, which is the most ancient and most modern respectively? A ( cdot 1,4 ) в. 3, 4 ( c cdot 2, ) D. 3, | 12 |

734 | In Rutherford experiment, number of particles scattered at ( 90^{0} ) angle are ( x ) per second.number of particles scattered oper second at angle ( 0^{0} ) is ( A ) B. ( 4 x ) ( c cdot 8 x ) D. ( 16 x ) | 12 |

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