Atoms Questions

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.

Atoms Questions

List of atoms Questions

Question NoQuestionsClass
1The 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
2An 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
3Match List-I with List-II.12
4Corpuscles are the tiny particles of
A. Light
B. Sound
c. waves
D. Radiation
12
5According to the Rutherford’s atomic model, the electrons inside the atom are
A. stationary
B. not stationary
c. centralized
D. None of these
12
6Consider 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
7Hydrogen 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
8The 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
9Photoelectric effect was successfully explained by
A. Planck
B. Hallwash
c. Hertz
D. Einstein
12
10With 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
11Find the wavelength of the most energetic photons in this series.
A . ( 1800 AA )
в. 1500 А
c. ( 1300 AA )
D. 1650 A
12
12How 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
13Atomic 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
14The 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
15The first artificial transmutation was
observed by Rutherford. If true enter 1 else enter 0
12
16The 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
17The 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
18according to Ruther-fordis atomic
model, the mass of the atom is evenly distributed throughout the atom
A. True
B. False
12
19The 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
20The 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
21The 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
22The 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
23In 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
24Rutherford’s alpha-particle scattering experiment was responsible for the discovery of:
A. atomic nucleus
B. electron.
c. proton
D. neutron.
12
25A ( 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
26Let ( 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
27What are the Cathode Rays?12
28When 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
29The 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
30If 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
31The element which was observed in
solar spectrum is
A. Helium
B. Xenon
c. Neon
D. Argon
12
32If ( 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
33Rutherford’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
34When 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
35Rutherford’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
36In 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
37Cathode 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
38For 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
39Which 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
40The number of waves in the third orbit
of H atom is
( mathbf{A} cdot mathbf{1} )
B. 2
( c cdot 4 )
( D )
12
41The 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
42Which 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
43If 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
44The 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
45In 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
46What is the major ( X ) -ray emitted by the sample?
A ( . K_{alpha} )
в. ( K_{beta} )
c. ( K_{gamma} )
D. ( K_{delta} )
12
47What 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
48State whether true or false:
Atoms normally have equal number of
protons and electrons
A. True
B. False
12
49The 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
50Rutherford 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
51If 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
52A 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
radiation.

12
53What is the effect on the thermion
beam in a cathode ray tube if the anode voltage value is reduced but remains
above zero?
12
54which 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
55The 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
56An 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
58If 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
59Can we use a screen coated with
barium platinocyanide in a cathode ray
tube? If so what effects do we observe
on the screen?
12
60In 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
61The 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
62One 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
63An ( 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
64The 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
65How many wavelengths of ( K r^{86} ) are
contained in one meter?
A . 1553164.13
B. 652189.63
c. 2347127.23
D. 1650763.73
12
66Rutherford’s scattering experiment is related to the size of the:
A. nucleus
B. atom
c. electron
D. neutron
12
67In 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
68The 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
69The 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
70In ( 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
71The 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
72Suppose 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
73What 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
74What 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
76Which 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
77When 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
78The 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
79Write three conclusion made by
Rutherford on the basis of alpha
particle scattering experiment.
12
80According to classical theory of
Rutherford, atom is
A. unstable
B. stable
C. positive
D. partially stable
12
81Calculate the radius of oxygen nucleus. Given that ( boldsymbol{R}_{boldsymbol{o}}=mathbf{1 . 1} times mathbf{1 0}^{-mathbf{1 6}} mathbf{m} )12
82The ( 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
83The 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
84Consider 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
85The 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
86What 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
87In 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
88An 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
89According 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
90What 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
91A 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
92A 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
93An 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
94As 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
95In 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
96Derive an expression for potential and kinetic energy of an electron in any orbit of a hydrogen atom according to Bohr’s atomic model.12
97Alpha-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
98Wavelengths 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
99What principle is violated here?
A . Laws of Motion
B. Energy conservation
c. Nothing is violated
D. Cannot be decided
12
100The 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
101An 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
102How does the ionization energy of an atom vary along a period and a group of the periodic table?12
103The path with which electron travels
from ( y ) -plate to screen is
A. Parabolic
B. Hyperbolic
C. Circular
D. Straight line
E . Helix
12
104Fraunh 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
106In 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
107In 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
108Calculate the wavelength of radiation
emitted when electron in a
hydrogen atom jumps from ( n=infty ) to
( boldsymbol{n}=mathbf{1} )
12
109A 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
110Assertion
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
111An 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
112Highly 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
113The 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
114Which 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
115The mass of photon at rest is
A ( cdot h nu / e^{2} )
в. ( h nu / c )
c. ( h nu )
D. Zero
12
116STRATION 29.5 Find the ratio of ionization energy of
Bohr’s hydrogen atom and doubly ionized lithium ion (Li?).
12
117The 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
118A 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
119What 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
121Rutherford experiment of scattering of ( alpha ) particles showed for the first time
that the atom has
12
122Which 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
123Rutherford 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
124If 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
125According 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
126A 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
127State two uses of a cathode ray tube12
128An 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
129In 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
130Which of the following pair is correct?
A. Rutherford; X-rays
B. Roentgen;electron
c. chadwick;neutron
D. J-J-Thomson;photon
12
131For 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
132The 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
133If an element X has mass number and
number of proton 8 then identify element ( X )
A .
B.
( c cdot 0 )
D. Ar
12
134When 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
136How 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
137An 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
138Assertion
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
139Nucleons is the name given for
and
A. electron, neutron
B. electron, proton
c. nucleus, electron
D. proton, neutron
12
140A 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
141The 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
142An 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
143A 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
144During an ( alpha ) -decay, the atomic number of parent element
and mass number
4
12
145In 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
146When 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
147The 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
148State any two postulates of Bohr’s theory of hydrogen atom12
149According to Bohr hypothesis, discrete quantity is
A. Momentum
B. Angular velocity
c. Potential energy
D. Angular momentum
12
150A 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
151In 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
152An 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
153Assertion
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
154The 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
155The 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
156Who 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
157The 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
158Smallest 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
159Identify 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
161The e/m ratio for electron was
determined by :
A. J.J Thomson
B. Planck
c. Einstein
D. schrodinger
12
162Name 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
163If 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
164The 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
165In 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
166The 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
168From Rutherford’s alpha particle scattering experiment give the experimental evidence for deriving the conclusion that12
169Let ( 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
170Describe the drawback of Rutherford’s
model of atom.
12
171A 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
172In 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
173Name a material which exhibits
fluorescence when cathode rays fall on ¡t.
12
174An 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
175If 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
177Total 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
178An 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
179Among the following particles, belongs to baryons.
A. neutron
B. ( mu ) -meson
c. positron
D. Pi-meson
12
180Using Bohr’s atomic model, derive an equation for radius of orbit of an electron.12
181What 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
182Number of spectral line in hydrogen
atom is
A. 6
B. 8
c. 15
D. None of the above
12
183In 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
184The 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
185A 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
186In 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
187Which person had convinced people on the fact that matter could be divided
forever?
A. Dalton
B. Democritus
c. Thomson
D. Aristotle
E. Rutherford
12
188Which transition will occur when a
hydrogen atom is irradiated with
radiation of wavelength 103 nm?
( A )
B. ( I I )
( c . I V )
( D )
12
189Calculate 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
190The 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
191In 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
192A 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
193An 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
194The 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
195The 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
196A 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
197An 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
198Particles 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
199The 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
200In 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
201Using 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
202In 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
203Gases 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
204The 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
205The 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
206The 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
207An 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
208Hydrogen 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
209An ( 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
210What will be the ratio of the radii of two
nuclei of mass numbers ( A_{1} ) and ( A_{2} ) ?
12
211The 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
212Assertion
In Rutherford’s gold foil experiment, very
few ( alpha ) -particles are deflected back.
Reason

Nucleus present inside the atom is heavy.
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
213the 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
214Using 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
215Gold 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
216The 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
217Which 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
218The 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
219The 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
220toppr
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
221According 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
222Ruthen-ford used which of the following elements in his scattering experiment
A. Gold
B. Silver
c. Alluminum
D. Antimony
12
223The 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
224Imagine 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
225The 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
226An ( 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
227The particle used by Rutherford in ( alpha ) -ray scattering experiment
was
A. neutron
B. electron
c. helium nuclei
D. x rays
12
228An 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
229The 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
230Rutherford scattering experiment is related to the size of the
A. Nucleons
B. Electron
c. Atom
D. Nucleus
12
231If 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
232The 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
233The 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
234An 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
235For 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
236If 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
237Matching 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
238Radius 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
239Wavelength 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
240A 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
242The 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
243In 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
245Electrons 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
246The 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
247An 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
248True or False
Rutherford’s atomic model was
successful in explaining stability of the
atom
12
249The 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
250a 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
251Identify 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
252The 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
253If ( 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
254n which transition is a Balmer series
photon absorbed?
( A cdot I )
3. II
( c_{1} )
D ( V )
12
255J.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
256If the ionization potential in the ground state for hydrogen is ( 13.6 e . V . ) then find
the excitation potential of the third
orbit.
12
257The 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
258When 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
259Find the shortest wavelength in Paschen series if, the longest
wavelength in Balmer series is ( 6563 A^{0} )
12
260The 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
261The 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
262In 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
263Find out the wavelength of the electron
orbiting in the ground state of hydrogen
atom
12
264Which 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
265In 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
266With 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
267Cathode rays are deflected
towards
A. positive electrode
B. negative electrode
c. both electrode
D. none of these
12
268Which 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
269When 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
270Explain the different types of spectral series in a hydrogen atom.12
271Explain the significance of quantum
number?
12
272The 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
273Radiation of ( lambda=155 ) nm was
irradiated to ( L i text { (work function }=5 e v) )
plate. The stopping potential.
12
274An 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
275The 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
276According 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
277If 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
278The 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
279The cathode ray particles originates in a discharge tube from the
A. Cathode
B. Anode
c. source of high voltage
D. Residual gas
12
280An 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
281Continuous spectrum is produced by
This question has multiple correct options
A. Incandescent electric bulb
B. Sun
C . Hydrogen molecules
D. Sodium vapor lamp
12
282In 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
283The 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
284How many times does the electron go
round the first Bohr orbit of hydrogen atoms in 1 s? (in peta Hz)
12
285Beta particles are essentially:
A. neutrons
B. protons
c. electrons
D. helium nuclei
12
286If 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
287Write the Rutherford – Soddi law of ratio
active decay and draw decay curve.
12
288If ( 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
289An 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
290An 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
291What 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
292Draw the diagram representing the schematic arrangement of the GeigerMarsdon experimental setup tor the alpha particle scattering.12
293The 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
294The Interaction energy between an electron and proton is very small when they are far apart.
A. True
B. False
12
295Assertion
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
296The 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
297Alpha 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
298A 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
299The 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
300Which 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
301The 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
302The 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
303The 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
304Imagine 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
305The 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
306How did Rutherford conclude that ( alpha )
particles were not deflected by the attraction of electrons inside the atom?
12
307Rutherford’s experiment for the first time proved that atom has:
A. Protons
B. Nucleus
c. Neutrons
D. Electrons
12
308Which of the following while in motion cannot be deflected by a magnetic field?
A. Protons
B. Cathode rays
c. Alpha particles
D. Neutrons
12
309Most 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
310Radius 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
311Name the three constituent of an atom
and state their mass and charge of
each. How are they distributed in an atom?
12
312Assertion
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
313An 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
314According to Bohr, ‘Angular momentum of an orbiting electron is quantised’ What is meant by this statement?12
315The 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
316The 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
317The 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
318The 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
319If 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
320Stability of an atom was successfully explained by Rutherford’s atomic model
A. True
B. False
12
321Write the different types of Hydrogen Spectral series. The Lyman series of Hydrogen spectrum lies in the ultraviolet region. Why?12
322A 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
323Name three constituents of an atom
and state mass and charge of each.
12
324When electron remains between orbits,
its momentum is :
A. quantized
B. dequantized
c. emitted
D. changed always
12
325Match 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
326If ( 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
327In 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
328A 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
329Name spectral series of hydrogen which lies in the ultraviolet region of
electromagnetic spectrum
12
330The 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
331As 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
332What 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
333When 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
334The 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
335The 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
336If ( 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
337The 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
338The particle that possesses half integral spin is
A. Photon
B. Pion
c. Proton
D. K-meson
12
339Which of the following particles cannot be deflected by magnetic field?
A. Electrons
B. Neutrons
c. ( alpha ) – particles
D. Protons
12
340A student measures the level of
radiation emitted by a radioactive
sample.

The table shows the readings she
records on the counter over a short
period of time.
Counter
reading/
( mathbf{9 6} )
98
counts per minute
The sample is removed and the counter
then shows a background radiation
reading of 4 counts per minute.
What is the best estimate for the
average count rate due to the
radioactive sample?
A. 96 counts per minute
B. 98 counts per minute
C . 100 counts per minute
D. 104 counts per minute

12
341Cathode 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
342In 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
343The 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
344The 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
345In
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
346Describe the JJ. Thomson method for
determining the specific charge of an
electron.
12
347For a neutral atom, the first ionization energy is equal to its electron affinity.
A. True
B. False
12
348Electrons 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
349When 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
350In a cathode ray tube, why is the
filament made of tungsten?
12
351An 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
352Monochromatic 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
353Rutherford’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
35421. 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
355There 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
356The 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
357The 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
358Assertion
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
359The 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
360If 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
361In which of the following fields cathode rays show minimum deflection?
A. Electric field
B. Magnetic field
c. Plasma field
D. Gravitational field
12
362Q 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
363The 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
364In 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
365To 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
366If 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
367An 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
368A 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
369Among the following, is unstable in free space.
A. Electron
B. Proton
c. Neutron
D. ( alpha ) -particle
12
370For 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
371The value of ( z ) is
A. 5
B. 4
( c .3 )
D. 2
12
372Check 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
373If ( 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
374An 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
375Which 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
376If 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
377The 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
378How many spectral lines are observed in spectra of ( boldsymbol{H} boldsymbol{e}^{+} ) ion?
A .2
B. 4
( c cdot 6 )
D.
12
379What 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
380The 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
381In 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
382How 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
383An 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
384As 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
385For 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
386What 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
387The 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
388In 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
389Rutherford’s alpha ( ( alpha ) ) particle scattering experiment resulted in discovery of:
A . electron
B. proton
c. nucleus in the atom
D. atomic mass
12
390The 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
391Magnetic 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
392Alpha particles are projected towards fixed at a nucleus. Which of the paths
shown in figure, is not possible
( A )
B.
( c )
( D )
12
393Line 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
394How 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
395The 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
396The 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
397The 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
398What is the shortest wavelength present in the Paschen series of
spectral lines?
12
399The 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
400Statement 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
401The 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
402An element has number of proton ( =7 ) Then what will be its atomic number?
A . 9
B. 7
( c cdot 16 )
( D )
12
403The 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
404Balmer 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
405Why 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
406The 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
407Which 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
408The 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
409The 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
410A 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
411What 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
412In 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
413In 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
414A 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
415If 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
416What 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
417In 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
418In 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
419The 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
420Find the value of ( boldsymbol{T} times mathbf{1 0}^{mathbf{1 7}} ) where ( boldsymbol{T} ) is
the orbital period of the electron?
12
421In 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
422Which 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
423Total 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
424The 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
the ( n^{t h} ) orbit of such a
hypothetical atom will be proportional to
( mathbf{A} cdot n^{6} )
B . ( n^{4} )
c. ( n^{2} )
D. ( n )

12
425How 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
426Which 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
427Nucleon is a common name for
A. Proton and electron
B. electron and neutron
c. neutron only
D. neutron and proton
12
428When 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
429In 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
430ILLUSTRATION 29.2 What is the angular momentum of an
electron in Bohr’s hydrogen atom whose energy is -3.4 eV?
12
431If 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
432A photon is a/an
A. Quantum of light
B. Quantum of matter
C. Positively charged paticle
D. Instrument for measuring light intensity
12
433A 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
434Write 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
435The 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
436A 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
437Surface 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
438Number of spectral lines in hydrogen
atom is
A . 8
B. 6
c. 15
D.
12
439Whenever 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
440The total of subshells in fourth energy
level of an atom is
A . 4
B. 8
( c cdot 16 )
D. 32
12
441In 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
442A 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
443What 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
444What is the rutherford’s atomic model?12
445A 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
446ILLUSTRATION 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
447A modified discharge tube is used as a
A. cathode ray oscilloscope
B. fluorescent tube
c. x-ray tube
D. all the above
12
448According 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
449In 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
450If 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
451According 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
452Answer the following question based on a hot cathode ray tube. Name the charged particles.12
453A 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
455When 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
456The 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
457The 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
458The 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
459State whether true or false:
( underline{e} ) ratio of proton is greater than that of ( bar{m} )
electron.
A . True
B. False
12
460The 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
461When is ( H_{alpha} ) line in the emission
spectrum of hydrogen atom obtained? Calculate the frequency of the photon emitted during this transition.
12
4621. 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
463A 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
464Branch 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
465Hydrogen 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
466Assuming 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
467Cathode 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
468The 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
469The 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
470The idea of quantum nature of light has emerged in an attempt to explain:
A . interference
B. diffraction
c. black body radiation
D. polarisation
12
471Thomson experimented with
A. protrons
B. cathode rays
c. alpha particles
D. gold foil
12
472A 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
473An 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
474which an electron in hydrogen atom
jumps from the third excited state to the ground state
12
475If 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
476An 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
477What 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
478The radius of nucleus varies with mass
no. as ( A^{1 / n} . ) The value of ( n ) is :
12
479In 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
480according to Ruther-fordis atomic
model, the mass of the atom is evenly distributed throughout the atom
A. True
B. False
12
481In ( 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
482If 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
483Which 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
484The nuclear radius is of the order of
B. ( 10^{-6} ) m
( mathbf{c} cdot 10^{-15} m )
D. ( 10^{-14} m )
12
485Diagram 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
486A 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
487In 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
488Draw a simplified labelled diagram of a hot cathode ray tube.12
489The 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
491The 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
492Particles having half integral spin are :
This question has multiple correct options
A . Electron
B. Photon
c. Proton
D. Neutron
12
493The 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
494The 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
495The 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
496The 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
497With 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
498ILLUSTRATION 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
499ne / ( m ) experiment we assume nature
of electron as
A. wave
B. particle.
c. photon
D. both a and b
12
500A 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
501The 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
502In Rutherford’s alpha scattering
experiment:

This question has multiple correct options
A. distance of closest approach is of the order of ( 10^{-14} mathrm{m} )
B. at the distance of closest approach, the kinetic energy of the ( alpha- ) particle is transformed into electrostatic
potential
C. the ( alpha- ) particles moving towards the nucleus will stop
moving and then start retracing its path
D. maximum number of ( alpha- ) particles went straight
through the metal foil

12
503How many electrons, protons and
neutrons are there in ( 16 g ) of ( _{8} O^{16} ? )
12
504The 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
505the 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
506The 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
507A 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
508A 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
509ILLUSTRATION 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
510The 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
511An 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
512The 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
513Which 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
514Linear 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
515Whenever 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
516In 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
517Identify 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
518Hydrogen 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
519If ( 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
520The 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
521When 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
522An 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
523If ( 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
524A 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
525Which person had convinced people that matter could be divided forever?
A. Dalton
B. Democritus
c. Thomson
D. Aristotle
E. Rutherford
12
526Which 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
527In 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
528Mark 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
529If 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
530The 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
531Two nuclei have mass numbers in the
ratio ( 1: 64 . ) What is the ratio of their
nuclear radii ?
12
532In 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
533lonized 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
534Radiation 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
535The 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
536When 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
537The 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
538Find the velocity of an electron having
an energy of 1280 electron volt. ( boldsymbol{m}= )
( 9.1 times 10^{-31} k g )
12
539In 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
540Bohr’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
541Which 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
542The spin of photon is
A.
B. ( frac{1}{2} )
c. ( frac{1}{3} )
D. None
12
543What were the three major observations
Rutherford made in the gold foil
experiment?
12
544The 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
545In 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
546The 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
547In 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
549Find the radius of a ( H e^{+} ) ion in the
state ( boldsymbol{n}=mathbf{1} )
12
550Pick 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
551The 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
552When 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
553The 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
554Three 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
555In 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
556In 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
557The 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
558Use 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. )
1.2 fermi).
A. ( =11.2 times 10^{-15} mathrm{m} )
В. ( =7.2 times 10^{-15} mathrm{m} )
( mathbf{c} .=8.2 times 10^{-15} mathrm{m} )
D. ( =9.2 times 10^{-15} mathrm{m} )

12
559The 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
560We 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
561Taking 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
562Assertion
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
563In 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
564Rutherford’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
565Ultraviolet 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
566If 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
567From 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
569The 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
570As 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
571The 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
572How 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
573The 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
574An 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
575According 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
576In 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
577When 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
578To get line spectrum, the substances are excited in their
A. Solid state
B. Molecular state
c. Gaseous state
D. Atomic state
12
579When 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
580If 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
581An 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
583In ( _{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
584A 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
585In 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
586Identify which of the following is the smallest discrete value of
electromagnetic energy?
A. photon
B. proton
c. electron
D. neutron
E. quark
12
587A 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
588State 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
589The 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
590A 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
591A 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
592With 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
593The 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
594According 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
595Let 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
596The 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
597What conclusion was drawn by Rutherford based on Geiger-Marsden’s experiment on scattering of alpha particles?12
598An 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
599The visible region of hydrogen spectrum was first studied by
A. Lyman
B. Balmer
c. Pfund
D. Brackett
12
600The 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
601State the postulate of Bohr’s theory regarding emission off a photon12
602The 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
603This particle balances the charges from the protons to make the atom neutral-
A. neutron
B. electron
c. nucleus
D. none of these
12
604Why 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
605Suppose 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
606Energy 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
607The 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
608Let ( 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
609If 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
610In 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
611The 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
612A 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
613Two 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
614According to drop model of nucleus which of the following cannot be explained?
A. Fission
B. Fusion
D. All of these
12
615The 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
61617. 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
617In 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
satisfied, if :
A. B is increased 208 times
B. E is increased 208 times
c. ( B ) is increased 14.4 times
D. None of the above

12
618The 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
619Name the phenomenon which shows the
quantum nature of electromagnetic radiation.
12
620An 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
621Energy of electron is an orbit of H-atom is
A. Positive
B. Zero
c. Negative
D. Unity
12
622The 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
623Assertion
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
624Calculate energy in kcal/mole
necessary to remove an electron in a hydrogen atom in fourth principal quantum number to infinity.
12
625Number of visible lines in Balmer
series.
A . 2
B. 4
( c .3 )
( D )
12
626An ( 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
627According 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
628Draw a neat labelled energy level diagram of the Hydrogen atom.12
629On 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
for all gases.
A. cathode rays
B. Anode rays
c. Both (1) and (2)
D. Neither (1) nor (2)

12
630Complete the following:
Mass ( = ) ( times ) density
A. Volume
B. Area
c. width
D. Density
12
631The Rydberg constant for Hydrogen is ( 1.097 times 10^{7} m^{-1} . ) Calculate the short
wavelength limit of Lyman series.
12
632In 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
633Which 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
634Name the phenomenon which shows the
quantum nature of electromagnetic radiation.
12
635For the following statements, write T for
True and ( F ) for False.
The mass of an electron is ( 1 / 2000 )
times that of proton.
12
636The photoelectric effect was experimentally studied by
A. Einstein
B. Lennard
c. Hertz
D. Rutherford
12
637An 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
638The 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
639A 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
640Who is known as the father of nuclear
physics?
A. Ernest Rutherford
B. Dalton
c. J.J. Thomson
D. E. Goldstein
12
641The ( 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
642The 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
643238
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
644The 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
645Consider 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
646Cathode 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
647A 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
648Both 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
649What is ionization potential of an atom?12
650Two 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
651When 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
653Assertion
In Rutherford’s gold foil experiment very
few ( boldsymbol{alpha} ) – particles are deflected back.
Reason

Nucleus present inside the atom is heavy.
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
654The e/m ratio of anode rays is constant irrespective of the gas filled inside the discharge tube
A. True
B. False
12
655An ( 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
656The 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
657The 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
658The maximum number of electrons in a
shell is
A ( cdot n^{2} )
B ( cdot 2 n^{2} )
( c cdot 2 n )
D. ( n )
12
659The 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
660The 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
661What 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
662JJ 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
664Discovery of the nucleus of an atom was due to the experiment carried out by:
A. Bohr
B. Rutherford
c. moseley
D. Thomson
12
665A 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
666The visible region of hydrogen spectrum was first studied by
A. Lyman
B. Balmer
c. Pfund
12
667Give the main postulates of Bohr’s model of an atom.12
668An 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
669In 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
670Rutherford’s alpha scattering experiment showed for the first time
that the atom has:
A . electrons
B. protons
c. nucleus
D. neutrons
12
671According 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
672the 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
673Packets of which of the following quantity best describe photons?
A. energy
B. mass
c. volume
D. power
E. waves
12
674The 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
675Energy 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
676ILLUSTRATION 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
677The 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
678A 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
679Let ( 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
680If 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
681Rutherford experiment of scattering of ( alpha ) -particles shows for the first time that
the atom has:
A. proton
B. nucleus
c. electron
D. neutron
12
682Doubly 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
683How 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
684The 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
685The 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
686Explain emission and absorption
spectra
12
687What is the effective mass of photon
having wavelength ( lambda ? )
12
688White 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
689In 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
690An 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
691The 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
692A 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
693If 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
694The number of neutrons in ( _{92} U^{235} )
nucleus is:
A . 327
в. 235
c. 143
D. 92
12
695The 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
696Describe 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
697State True or False.
Nucleus always contains proton.
A. True
B. False
12
698Diagram shows an electron gun inside
cathode ray tube. Label the screen with
the letter ( S ).
12
699State 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
700Explain the spectral series of hydrogen atom (diagram not necessary)12
701What 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
702The 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
703Explain emission and absorption
spectra
12
70434. 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
705The 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
706The 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
707A 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
708In 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
709An incandescent filament emits a
spectrum which is :
A. line spectrumm
B. band spectrum
c. continuous spectrum
D. characteristic spectrum
12
710Identify the principal quantum number for the last electron that is added to
sodium?
A.
B. 2
( c cdot 3 )
D. 5
E. 4
12
711Hydrogen 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
712Using 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
713The 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
714Which 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
715In 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
716The 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
717In 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
718If an element has 22 electrons then
what will be its atomic number?
A . 10
B. 25
c. 15
D. 22
12
719A 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
720There 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
721List out any two limitations of Bohr atom model.12
722In 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
723The 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
724Magnetic 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
725In 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
726With 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
7279. 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
728One 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
729A 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
730The photoelectric effect proves that light consists of:
A. Photons
B. Electrons
c. Electromagnetic waves
D. Mechanical waves
12
731What 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
732In 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
733Schrodinger 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
734In 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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