Physical And Chemical Changes Questions

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

Physical And Chemical Changes Questions

List of physical and chemical changes Questions

Question NoQuestionsClass
1( 23 g ) of sodium will react with methyl
alcohol to give:
A. one mole of oxygen
B . 22.4dm ( ^{3} ) of hydrogen gas at NTP
c. 1 mole of ( H_{2} )
D. ( 11.2 L ) of hydrogen gas at NTP
7
2Dissolving sugar in water is an example
of:
A. physical change
B. chemical change
c. neutralisation
D. none of these
7
3A chemical reaction in which energy is
liberated is called :
A. exothermic reaction
B. physical change
c. endothermic reaction
D. photochemical reaction
7
4Anaerobic bacteria digest animal waste and produce biogas(Change-A). The biogas is then burnt as fuel(Change-B). The following statements pertain to these changes. Choose the correct one.
A. Process-A is a chemical change
B. Process-B is a chemical change
C. Both processes A and B are chemical changes
D. None of these processes is a chemical change
7
5Iron and rust are the same substances.
A. True
B. False
7
6Substances react with each other and
form chemical bonds to:
A. become stable compounds
B. to decrease their energy
C. to increase their energy
D. to form newer compounds
7
7What is a chemical change?
A. Change in size, shape
B. Change from one substance to another new substance
C. Change in temperature from lower to higher
D. None of above
7
8Rusting is a special term, given to the corrosion of which metal?
A. zinc
в. copper
c. Nickel
D. Iron
7
9What are the essential conditions for
rusting to take place? This question has multiple correct options
A. Presence of pure water
B. Presence of oxygen
c. Presence of impure water
D. Presence of oxygen alone is enough
7
10An iron ball at ( 50^{circ} C ) is dropped in a
beaker of water at ( 50^{circ} C . ) The heat will
A. Not flow from iron ball to water
B. Not not flow from iron ball to water or from water to iron ball
c. Not flow from water to iron ball
D. Increase the temperature of both
7
11Which of the following is a chemical change:
A. melting of ice
B. boiling of water
c. rusting of iron
D. tearing a paper
7
12Two changes are stated below:
(i) A piece of magnesium gives of bright flames when burnt
(ii) A piece of iron glows red when heated strongly. Which of these is a chemical change?
A. i only
B. ii only
D. None of the above
7
13For rusting of iron to take place, are required.
( A cdot H_{2} O ) and ( O_{2} )
( B cdot C O_{2} ) and ( O_{2} )
( mathbf{C} cdot mathrm{H}_{2} ) and ( mathrm{H}_{2} mathrm{O} )
D. ( mathrm{N}_{2} ) and ( mathrm{H}_{2} mathrm{O} )
7
14Reactions that take place under the influence of electricity are called:
A. Electrolytic reaction
B. Hydrolytic reaction
c. condensation reaction
D. Photolytic reaction
7
15Give four reasons why burning of a magnesium ribbon in air is considered a chemical change.7
16You mix two colorless solutions and the
resulting mixture becomes cloudy What type of reaction was observed?
A . A physical reaction
B. A redox reaction
C . A precipitation reaction
D. An acid base reactions
7
17Which of the following is a feature of physical change?
A. It is reversible
B. It is temporary
c. No new substance is formed
D. All of the above
7
18Which of the following is true about
rusting of iron?
A. The monetary loss due to rusting is huge.
B. For rusting, the presence of both oxygen and water (or water vapor) is essential
C. If the content of moisture in air is high, which means if it is more humid, rusting becomes faster
D. All of the above.
7
19The plant of ONGC got collapsed in the recent years which was a chastic
damage to them. How can we prevent
this?
7
20All of the following processes involve a separation of either a mixture into its components or a compound into elements. For each, decide whether the physical process or chemical reaction is required.
a. Sodium metal is obtained from the
substance Sodium chloride.
b. Iron filings are separated from the sand by using a magnet,
c. Sugar crystals are separated from sugar syrup by evaporation of water.
d. Fine crystals of Silver chloride are separated from a suspension of the crystals in water.
e. Copper is produced when Zinc metal is placed in a solution of Copper (II) sulphate, a compound.
A. a, b, c, d, e-physical
B. a, d, b, c, e – chemical
c. b, c, d- physical ; a, e- chemical
D. e a, b – physical ; c, d- chemical
7
21Which of the following is not a physical change?
A. Boiling of water to give water vapour
B. Melting of ice to give water
c. Dissolution of salt in water
D. combustion of Liquefied Petroleum Gas (LPG)
7
22Reactions take place in
presence of light.
A. Electrolytic reaction
B. Hydrolytic reaction
c. condensation reaction
D. Photochemical reaction
7
23Melting of butter is a physical change.
A. True
B. False
7
24Two changes are stated below:
(i.) A piece of magnesium gives of bright flames when burned.
(ii). A piece of iron glows red when heated strongly. Which of these is a physical change?
A. Only i
c. Both i and ii
D. Neither i nor ii
7
25Which of the following is a chemical change?
A. Boiling of eggs
B. Evaporation of water
c. Precipitation of snow
D. Melting of wax
7
26Formula of rust:
( mathbf{A} cdot F e_{2} O_{3} cdot x H_{2} O )
B. ( F e_{3} O_{4} cdot x H_{2} O )
( mathbf{c} cdot F e_{6} O_{16} cdot x H_{2} O )
D. None of the above
7
27What kind of changes is undergone
when an electric bulb glows?
A. A physical change
B. A chemical change
c. Both a physical and a chemical change
D. A permanent change
7
28Classify the following as physical or chemical properties. Zinc dissolves in hydrochloric acid with the evolution of hydrogen gas.
A. Chemical
B. Physical
c. Both ( A ) and ( B )
D. None of these
7
29Select the one that is not a chemical change?
(a) Dissolution of ammonia in water.
(b) Dissolution of carbon dioxide in water.
(c) Dissolution of oxygen in water.
(d) None of the above is a chemical change.
7
30Explain how painting of an iron gate prevents it from rusting?7
31Statement ( -1: P b O_{2} ) is an oxidising agent and reduced to Pbo.

Statement – 2 : Stability of Pb (II) > Pb
(IV) on account of inert pair effect.
A. Statement – – lis True, Statement – 2 is True; Statement 2 is a correct explanation for Stetement- –
B. Statement – 1 is True. Statement – 2 is True; Statement 2 is NOT a correct explanation for Statement-
c. Statement – – lis True, Statement – 2 is False
D. Statement-lis False, Statement- – 2 is True

7
32Steel is electroplated with zinc
because zinc has:
A. more lustrous
B. less corrosion resistance
c. more corrosion resistance
D. more heavy
7
338.
A burning of candle represents
(a) physical change (b) volume change
(c) chemical change (d) none of the above
7
34( boldsymbol{H}_{2} boldsymbol{O}_{(l)} rightleftharpoons boldsymbol{H}_{2} boldsymbol{O}_{(g)} )
What type of change is represented by
the equation above?
A. This is a physical change because the equation is balanced
B. This is chemical change because the equation is balanced
c. This a physical change because the same compound is represented as both the reactant and product.
D. This a chemical change because the same compound is represented as both the reactant and product
7
35Assertion
Galvanized iron does not rust.
Reason
Zn has a more negative electrode
potential than Fe.
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
7
36Crystalisation takes place by the
process of :
A. evaporation
B. condensation
c. sublimation
D. liquefication
7
37Which one of the following substances increase in weight by burning in air?
A. woodd
B. Magnesium
c. Paper
D. candle
7
38Three substances given below are kept in the open for a few days and some
changes were observed.

Which of the substances will show
chemical changes?
A. Eggs
B. Plastic bottle
c. Both eggs and moth balls
D. All eggs, plastic bottle and the moth balls

7
39Insoluble impurities from solution during crystallization are removed by :
A. drying
B. filtration
c. heating
D. cooling
7
40Which of the following is a physical change?
A. Photosynthesis
B. Melting of steel
c. Burning of wood
D. Radioactive decay
7
41Which of the following is a physical change?
A. Magnetisation of iron
B. Curdling of milk
c. Burning of a candle
D. cooking of food
7
42In early winter mornings, we can see drops of water on the blades of grass. This is because of :
A. photosynthesis
B. transpiration
c. condensation
D. water cycle
7
43While forming crystals, it is important
to:
A. evaporate to dryness to get purest possible crystals
B. attach gas syringes to collect fumes
C . not evaporate water of crystallization
D. use high flames
7
44Large crystals of pure substances can be formed from their solutions during
A. crystallization
B. evaporation
c. expansion
D. contraction
7
45Which of the following is NOT a chemical change?
A. Digestion of food
B. Precipitation of rain and snow
c. Rusting of iron
D. Burning of paper
7
46Which of the following are physical changes?
(i) Melting of iron metal
(ii) Rusting of iron
(iii) Bending of an iron rod
(iv) Drawing a wire of iron metal
A. (i), (ii) and (iii)
B. (i), (ii) and (iv)
c. (i), (iii) and (iv)
D. (ii), (iii) and (iv)
7
47When magnesium is burnt in air, the weight of magnesium:
A. increases
B. decreases
c. remains same
D. Depends on the atmosphere
7
48energy in plants is used by man in the form of food.
A. Chemical
B. Electrical
( c cdot ) Bio
D. Physical
7
49Chemical changes are
A. temporary, reversible and a new substance is produced
B. always accompanied by exchange of light
C . permanent, irreversible and a new substance is produced
D. never accompanied by exchange of light and heat energy
7
50Churning of milk cream to get butter is
( a )
changes.
7
51Crystallisation is an example of chemical change.
A. True
B. False
7
52Which of the following is not a physical change?
A. Tearing a paper
B. Bending an iron rod
c. Freezing water into ice
D. curdling of milk
7
53Dissolution of salt in water is a
change
7
54Corrosion is the natural process which
converts a refined metal to its:
A . oxide
B. hydroxide
c. sulphide
D. all of these
7
55Explain energy changes in a chemical change.7
56The reacting surface is reduced when the particle size is:
A . small
B. large
c. moderate
D. both a and c
7
57In basic medium, which of the following
colour is obtained when
phenolphthalein is added?
A. Pink
B. Colourless
c. Yellow
D. Green
7
58Neutralization is a:
A. physical change
B. chemical change
C. sometimes physical and sometimes chemical change
D. neither physical nor chemical change
7
59Take some clean iron nails and place them in the three test tubes prepared as
under:

Test tube A: Contains boiled water and a
thin layer of oil

Test tube B: Contains a small cloth bag
containing soda lime Test tune C: Contains ordinary water. Some nails are kept under water and
some more are suspended above the
water surface
All the test tubes are tightly closed after
placing the nails. After some time what
will you observe?
This question has multiple correct options
A. Nail A rusts
B. Nail B rusts
C. Nail C rusts
D. Nail A does not rust

7
60What do you mean by Corrosion?7
61A process in which a change is brought by a ferment such as yeast, enzymes which convert sugar into ethyl alcohol is
called:
A. polymerisation
B. acetylation
c. hydrogenation
D. fermentation
7
62Drying of a shirt in the sun is an
example of changes.
7
63The melting point of cadmium bromide
is ( 568^{circ} mathrm{C} ). Which of the following
equations best describes what occurs when cadmium bromide is heated to
( 568^{circ} C ? )
A ( cdot operatorname{CdBr}(s) rightarrow operatorname{CdBr}(l) )
B . ( operatorname{CdBr}_{2}(s) rightarrow operatorname{CdBr}_{2}(l) )
c. ( operatorname{CdBr}_{2}(s) rightarrow C d(s)+B r_{2}(g) )
D. ( operatorname{CdBr}_{2}(s) rightarrow C d^{2+}(a q)+2 B r^{-}(a q) )
7
64What is chemical change?7
65Chemical combination involves:
A. Combination of two atoms.
B. Combination of only same type of elements.
C. Combination of only same type of compounds
D. Combination of any two or more elements or compounds.
7
66Corrosion is a chemical reaction that
involves:
A. The inside of the object changing from an element to a compound
B. The surface of the object changing from an element to a compound
C. Nothing happens
D. The surface of the object changes from one element into another element
7
67If an ice cube is wrapped in a black cloth and another in an aluminium foil
and both are placed in sunlight, which will melt first?
7
68On decreasing temperature, a liquid turns into solid. This is:
A. condensation
B. melting
c. freezing
D. sublimation
7
69A change that alters the composition of a substances is known as a chemical
change.
7
70In a chemical change:
A. Molecules of substance do not change
B. Molecules of substance change
C. Substance remain the same
D. Change is reversible
7
71Explain why rusting of iron objects is faster in coastal area than in deserts.7
72Match the columns
begin{tabular}{ll|l}
& I & \
(a) & Physical change & (I) & Curdling of milk \
(b) & Chemical change & (ii) & Demagnetisation of magnets \
& (iii) & Digestion of food \
& (iv) & Crystallisation of substance \
& (v) & Rusting of iron
end{tabular}
( A cdot a-i, i i, ) iii, ( b-i v, v )
B. ( a-i i, ) iv, ( b-i, ) iii, iv
( mathbf{C} cdot a-i i, i v, b-i, ) iii, ( v )
( mathbf{D} cdot a-i i i, v, b-i, ) ii, iv
7
73When metals corrodes, it is being:
A. dissolved into surrounding moisture
B. weakened structurally
C. chemically combined with another metal
D. reacted with oxygen
7
74Which factor when increased will cause
an uncatalyzed reaction to proceed more quickly?
A. Exothermic
B. Particle Size
c. Endothermic
D. catalyst
7
75To find the n-factor in the following chemical changes. ( boldsymbol{K}_{2} boldsymbol{C r}_{2} boldsymbol{O}_{7} stackrel{boldsymbol{H}^{+}}{rightarrow} boldsymbol{C r}^{3+} )7
76State whether true or false:
Cutting a log of wood into pieces is a chemical change.
A. True
B. False
7
77Iron rusts in presence of air and moisture.
A . True
B. False
7
78Which of the following is not a physical change?
A. Melting of wax
B. Tearing a piece of paper
c. cutting wood
D. Digestion of food
7
79Pick up the correct statement:
A. Boiling points of alkyl halides are greater than those of the corresponding alkanes.
B. In water, the solubility decreases as ( C H_{3} O H> ) ( C_{2} H_{5} O H>C_{6} H_{5} O H )
C. Aniline is a weaker base than ammonia.
D. All of the above.
7
80Which of the following is a condition for burning?
A. Ignition temperature
B. Combustible substance
c. Gaseous environment
D. All of above
7
81hemical change when
A change is said to be a chemical char
of new substances
physical properties
(a) it is accompanied by energy change
(b) it is accompanied by formation of new
(c) it is accompanied by change in physical
(d) All the above are correct
mesa decomposition reaction 2
7
82Boiling water is a ( —- ) change
because
A. Physical, the gaseous water produced is chemically identical to the liquid water the process began with
B. Physical, the water was disappeared
C. Chemical, heat was required for the change
D. Chemical, the process produced a gas
7
83When a candle burns, both physcial and chemical changes takle place. Identify these changes. Give another example of a familiar process in which both the
chemical and physical changes take place
7
84When magnesium ribbon burns in air, it forms white ash. The chemical name of
white ash is:
A. Magnesium dioxide
B. Milk of magnesium
c. Milk of magnesia
D. Magnesium oxide
7
85When a little sulfuric acid is added to
water in a beaker, the water becomes
hot.
7
86When lemonjuice is added to milk it curdles. This is an example of:
A. coaguluation
B. sublimation
c. chemical decomposition reaction
D. photochemical change
7
87For a chemical change to occur the particles should be in:
A . equilibrium
B. same temperature
c. close contact
D. high pressure
7
88A change in the physical state can be
brought about:
A. only when energy is given to the system
B. only when energy is taken out from the system
c. when energy is either given to, or taken out from the
D. without any energy change
7
89Sun tanning is a/an:
A . physical change
B. chemical change
( c . ) both a and ( b )
D. intermediate
7
903.
Above phenomena represents ?
(a) Physical change
(b) Chemical change
© Both physical and chemical
(d) None of the above
7
91Heating of sugar solution is a chemical change
A . True
B. False
7
92An experiment is conducted to fully
oxidize a sample of magnesium ribbon.
Which factor would do the most to
make the reaction proceed more
quickly?
A. Vigorous heating of the reaction vessel
B. Addition of carbon dioxide to the reaction vessel.
C. Removal of oxygen from the reaction vessel.
D. Carefully folding the magnesium sample into a small, cubic shape.
E. Addition of nitrogen gas the the reaction vessel.
7
93Photosynthesis in plants is a change
A. chemical
B. physical
c. both ( A ) and ( B )
D. none of the above
7
94VIOLI
How many of them are chemical changes.
melting of ice, glowing of bulb, souring of milk, burning of
paper, burning of candles av o ts
7
95Which of the following is a physical change?
a) Hammering of a red hot iron rod to
make a flat sheet.
b) Formation of ice by cooling of water.
c) Rising up of water vapors from sea to
make clouds.
d) Heating of charcoal in air to high temperature till it begins to flow.
( A cdot a, b ) and ( c )
B. b, cand d
c. ( c, ) d and a
D. ( d, ) a and ( b )
7
96Assertion
The burning of a candle is both a
physical and a chemical change.
Reason
Burning of candle melts the wax and hence physical state of wax has changed from solid to liquid. Again the wax combines with the atmosphere oxygen and changes to carbon dioxide, heat and light.
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
7
97Chemical change are characterised by
A. formation of new substance
B. release of energy
c. absorption of energy
D. reversible
7
98Which of the following represents
correct statement(s)?
A. Salt can be obtained by the evaporation of sea water.
B. The salt obtained during crystallisation is pure and its crystals are large.
C. After crystallisation, the shape of the crystals can be seen clearly.
D. Large crystals of pure substances cannot be formed from their solutions.
7
99Why does a blacksmith heat the metal
rim to fix it on a cart wheel?
7
100Statement (1) : Composition and molecular structure of the reactants
can be changed by having a chemica
change
BECAUSE
Statement (2): It is said to be a
chemical reaction when new
substances and new bonds are formed
and old bonds are broken.
( A cdot(1) ) is true
(2) is true, (2) is the correct explanation of
(1)
B. (1) is false, (2) is true
c. (1) is true,
(2) is true
D. (1) is false,
(2) is false
( E .(1) ) is true,
(2) is false
7
101Classify the following as physical or chemical change.
Metallic sodium is soft enough to be cut
with a knife.
A. Chemical
B. Physical
c. Both ( A ) and ( B )
D. None of these
7
102Give reasons to show that the following are chemical changes:
Burning of magnesium in the air.
Select the correct statements:
This question has multiple correct options
A. New substance is formed with different properties
B. New substance is formed and has the same properties
c. The reaction is reversible
D. The reaction is irreversible
7
103Milk curdles when lemon juice is added.
This is :
A. evaporation
B. coagulation
c. reversible
D. photochemical change
7
104Conversion of milk into curd is :
A. a physical property of milk
B. a chemical property of milk
C . a physical change
D. a chemical change
7
105Rusting of iron is a chemical change because:
A. it is temporary
B. it can be cleaned and the original substance recovered
c. it is a slow reaction
D. a new substance is formed
7
106Identify the physical change in the following:
A. Reaction of zinc metal with dilute sulphuric acid
B. Formation of solutions of soluble substances in water
c. Burning of coal
D. Photosynthesis
7
107Q Type your question-
a. ( boldsymbol{F e}(boldsymbol{s}) rightarrow boldsymbol{F} boldsymbol{e}^{2+}(boldsymbol{a} boldsymbol{q})+boldsymbol{2} boldsymbol{e}^{-}( ) at anodic
site)
b. ( O_{2}(g)+4 H^{oplus}(a q)+4 e^{-} rightarrow 2 H_{2} O(l) )
(at cathodic site)
c. ( 4 F e^{2+}(a q)+O_{2}(g)+4 H_{2} O(l) rightarrow )
( mathbf{2} boldsymbol{F} boldsymbol{e}_{mathbf{2}} boldsymbol{O}_{3}(boldsymbol{s})+boldsymbol{8} boldsymbol{H}^{oplus} )
d. ( boldsymbol{F e}_{2} boldsymbol{O}_{3}(boldsymbol{a} boldsymbol{q})+boldsymbol{x} boldsymbol{H}_{2} boldsymbol{O}(boldsymbol{l}) rightarrow )
( boldsymbol{F} boldsymbol{e}_{2} boldsymbol{O}_{3} cdot boldsymbol{x} boldsymbol{H}_{2} boldsymbol{O} )
Reason
Rusting is accelerated in the presence
of ( N a C l ) and ( C O_{2} )

Read the above assertion and reason
and choose the correct option regarding
it
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

7
108What are the essential things required
for rust?
A. Strong acid, oxygen, an electrical current
B. Sunlight, air, salt
c. water, oxygen, a metal
D. An anode, a cathode, salt
7
109What do you mean by corrosion? How
can you prevent it?
7
110When heated in air, brown copper
powder turns black. This black powder would turn brown again when heated
with:
A. ( C O )
в. ( O_{2} )
( mathrm{c} cdot mathrm{H}_{2} )
D. ( N H_{3} )
7
111The surface area of the reacting particle can be increased by:
A. Mixing
B. Powdering
c. cooling
D. Both a and
7
112Which of the following are chemical changes?
(i) Melting of iron metal
(ii) Rusting of iron
(iii) Bending of an iron rod
(iv) Drawing a wire of iron metal
A. only (ii)
B. (ii) and (iii)
c. (iii) and (iv)
D. (i) and (iv)
7
113Rust forms on:
A. Tin
B. copper
c. Iron
D. Lead
7
114The process of obtaining salt by evaporation of seawater is known as:
A. crystallisation
B. sedimentation
c. galvanization
D. amalgamation
7
115Renewable sources of energy
are produced in nature:
A. biennial
B. annually
c. continuously
D. quarterly
7
116What conditions are required for
rusting to take place?
A. Water only
B. Oxygen only
c. water and oxygen
D. water and carbon dioxide
7
117Crystallisation is an example of
A. physical change
B. biological change
c. chemical change
D. fundamental change
7
118Which observation is definite sign that a chemical change has occurred?
A. color change
B. Bubble formation
c. change in temperature
D. Precipitate formation
E. Salt dissolving
7
119In acid medium, which of the following
colour is obtained when
phenolphthalein is added?
A. Pink
B. Yellow
c. Green
D. Colourless
7
120Which of the following is a true term regarding chemical reactions?
A. Reversible
B. Irreversible
c. Interchangeable
D. reliable
7
121Photosynthesis requires:
A. water
B. sunlight
c. chlorophyll
D. all of the above
7
122The process of forming large crystals of pure substances from their solutions is
known as
A. evaporation
B. purification
c. condensation
D. crystallisation
7
123Which of the following is a physical change?
A. Burning of coal
B. Photosynthesis
c. Dissolving sugar in water
D. Digestion of food
7
124Which of the following is a physical change ?
A. solubility in water
B. combustibility
c. aerial oxidation
D. reaction with water
7
125The thermodynamic efficiency of a cell is given by:
A ( cdot frac{Delta H}{Delta G} )
B. ( frac{n F E_{c l l}}{Delta G} )
( mathrm{c} cdot-frac{n F E_{c l}}{Delta H} )
D. zero
7
126Melting of wax is a change.
A. physical
B. chemical
c. both ( A ) and ( B )
D. none of the above
7
127Assertion
Fe is protected from corrosion by
connecting Mg metal with it.
Reason
Fe acts as cathode and Mg as anode
which gradually disappears.
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
7
128The change given below is an example
of :
Hydrogen ( + ) Oxygen ( stackrel{text {heat}}{longrightarrow} quad ) Water
A. Physical change
B. Chemical change
c. Both A and B
D. Neutralization reaction
7
1293.
Select the incorrect statements.
(a) A physical change can be easily reversed by a slight
change of conditions.
(b) A physical change is accompanied by a change in color
of the reacting substances.
(c) It is possible to characterise a chemical reaction by
only a change in state
(d) All the above are incorrect.
7
130Which of the following statements is
true?
A. Chemical changes are reversible
B. Only very few chemical reactions are reversible
C. Growth of a tree is periodic change
D. Rusting of iron is a fast change
7
131To protect iron from corrosion and rusting , it is electroplated with
A. zinc
B. Chromium
c. Nickel
D. Aluminum
7
132The reaction can be aided by increasing the:
A. Time
B. Pressure
c. surface area of particle
D. All of above
7
133Assertion : The formation of rust is a chemical change.
Reason: For the formation of rust iron must be exposed to
air and water.
7
134A synthetic indicator phenolphthalein
gives colour in basic
solution.
A . red
B. blue
c. pink
D. colourless
7
135Burning of wood is a ( _{-}-_{-}-_{-} ) change.
A . reversible
B. physical
c. irreversible
D. all of these
7
136Which of the following is not a physical change?
A. Dissolution of sugar or salt in water
B. Powdering of sugar
c. Mixing of iron particles and sand
D. Burning of paper
7
137One of most common solvent used for
crystallization is:
A. syrup
B. normal saline
c. water
D. sulphuric acid
7
138The dissolution of copper sulfate in
water is a physical change where as
that of granulated zinc in dilute hydrochloric acid is a Chemical Change.
7
139What are the conditions for a chemical
change?
A. Combining particles are in close contact.
B. Energy is suppliedd
c. Both A and B
D. None of these.
7
140Does the size of the paper change after
making an aeroplane by folding it or by cutting it?
7
141Solvent dissolve large amount of solute
at
A. room temperature
B. boiling temperature
c. freezing temperature
D. less than room temperature but more than freezing temperature
7
142Assertion
Catalyst is a substance which takes
part in a chemical reaction, undergoes chemical change and alters the rate of a
reaction
Reason
Catalyst is a substance which does not
take part in a chemical reaction, but changes the rate of reaction
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
7
143Steel is preferred over iron in construction of ships because:
A. melting point of steel is higher than iron
B. steel is more uniform than iron
c. steel does not rust
D. tensile strength of steel is not high
7
144Which metal is protected by a layer of its own oxide?
A . ( A l )
в. ( A g )
c. ( A u )
D. ( F e )
7
145For rusting of iron to take place
are required.
( A cdot O_{2} ) and ( C O_{2} )
B. ( H_{2} O ) and ( N_{2} )
( mathbf{c} cdot H_{2} O ) and ( O_{2} )
D. ( H_{2} O ) and ( H_{2} )
7
146LULUIU O CULTOUUUUUU
1.
Assertion : Burning of paper is a physical change.
Reason: The products formed on burning of paper can not
be easily converted back to paper.
7
147Which of the following is a chemical change?
A. Breaking of a brick
B. Evaporation of a liquid
c. Burning of a candle
D. Moving of a wheel
7
148Why does a lump of cotton wool shrink
in water?
7
149Which of the following statements is
not correct?
A. In a chemical change, color of the object may change.
B. In a chemical change, heat will always be released.
C. A chemical change always involves a physical change.
D. Rusting of iron becomes faster when humidity is high.
7
150The diagram shows experiments involving the rusting of iron. The following results were suggested. 1 In tube ( P ), the iron nails rust.
2 In tube ( Q ), the iron nails do not rust.
3 In tube ( R ), the iron nails do not rust.
Which results are correct?
A . 1 and 2 only
B. 1 and 3 only
c. 2 and 3 only
D. 1,2 and 3
7
151Give the two methods by which rusting of iron can be prevented.7
152Glowing of an electric bulb is a
change.
A. physical
B. chemical
c. both physical and chemical changes
D. none of these
7
153Some pieces of chalk were taken and mixed with water. In this change, how many new substances are formed?
( A )
B. 2
( c cdot 3 )
D. No new substance is formed
7
154Condensation of steam is not a
chemical change.
A. True
B. False
7
155Initiate chemical change without themselves undergoing any permanent change
A . Reactants
B. Catalyst
c. Products
D. All of above
7
156Heating of sugar solution is a chemical
change. State whether the statement is true or false
A. True
B. False
c. Either
D. Neither
7
157Which of the following are chemical changes?
(a) Growth of a plant
(b) Rusting of Iron
(c) Mixing of iron fillings and sand
( (d) ) Cooking of food
(e) Digestion of food
( (f) ) Freezing of water
( (g) ) Burning of a candle.
7
158Dissolution of common salt or sugar in water is an example of:
A. physical change
B. chemical change
c. both A and B
D. none of the above
7
159Dissolution of carbon dioxide gas in
water is ( -ldots-ldots- ) change.
A . chemical
B. physical
c. both of ( A ) and ( B )
D. none of the above
7
160When baking soda is mixed with lemon juice, bubbles are formed with the evolution of a gas.What type of change is it? Explain.7
161Explain how a metal rim slightly
smaller than a wooden wheel can be
fixed on it.
7

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