ChemicalReactions
and Equations
Multiple Choice Questions (MCQs)
Q. IWhich of the following is not a physical change?
(a) Boiling of water to give water vapour
(b) Melting of ice to give water
(c) Di_solution of salt in water
d Combustion of Liquefied Petroleum Gas (LPG)
Thinking Process
)Chemical change takes place on the molecular level and it produces a new substance.
(1) Physical change involves change in physical properties and it does not produce a
new substance.
Ans. (d) Combustion of Liquefied Petroleum Gas (LPG) is a chemical change. Because it is an
irreversible reaction and new products, carbon dioxide and water vapour are formned
and lot of heat is also produced during the reaction.
Rest three are physical changes as no new products are formed.
Q.2The following reaction is an example of a
4NH, (g) + 50, (g) - 4NO (g) + 6H,0 (g)
1. displacement reaction
2. combination reaction
3. redoX reaction
4. neutralisation reaction
(a) 1and 4 (b) 2 and 3 (c) 1and 3 Va) 3 and 4
Thinking Process
In this reaction, NH, is changing into NO Removal of hydrogen froma substance is
called oxidation. So, NH, is undergoing oxidation. O, is changing into H,0 The addition
of hydrogen to a substance is called reduction. So, o, is undergoing reduction.
Ans. (d) It is a redox reaction because oxidation and reduction both take place simultaneously
in this reaction. Also, it is a displacement reaction because H of NH, has been
displaced by oxygen.
, NCERT Exemplar (Class X) Solutions
given reaction are correct?
Q. 3Which of the following statements about the
3Fe(s) + 4H,0(g) ’ Fe ,0, (s) + 4H, (g)
1. Iron metal is getting oxidised.
2. Water is getting reduced.
3. Water is acting as reducing agent.
4. Water is acting as oxidising agent.
a L2 and 3 (b) 3and 4
Ð1, 2 and 4 (d) 2 and 4
Ans. (c) Fe is gaining oxvgen to give Fe,0, H,O is losing oxygen to give H,. The substance
which UIses the other substance in a chemical reaction is known as an oxid1sing
agent. So. water is ating as oxid1sing agent.
Q. 4 Which of the following are exothermic processes?
1. Reaction of water with quick lime
2. Dilution of an acid
3. Evaporation of water
4. Sublimation of camphor (crystals)
a 1and 2 (b) 2and 3
(c) Iand 4 (d) 3 and 4
Thinking Process
ExothermIc processes are those in which heat is released along with the formation of
Ans. (a) When quick lime reacts with water, a large amount of heat is released along with the
fomationof calcium hydroOxide. Similarly, the process of dissolving an acid or base in
water s a highly exothermic reaction. Evaporation of water and sublimation of
campnor are endothermicreactions.
0.5 Three beakers labelled as A, Band Ceach containing 25 mL of water were
taken. Asmall amount of NaOH, anhydrous CuSO, and NaCl were added to
the beakers A, B and C respectively. It was observed that there was an
increase in the temperature of the solutions contained in beakers Aand B,
whereas in case of beaker C, the temperature of the solution falls. Which
one of the following statement(s) is(are) correct?
1. In beakers Aand B, exothermic process has occurred.
2. In beakers Aand B, endothermic process has occurred.
3. In beaker C, exothermic process has occurred.
4. In beaker C, endothermic process has occurred.
(a) Only 1 (b) Only2
l and 4 (d) 2 and 3
Ans. (c) ks in case of beakers Aand Bheat is given out, so temperature became high, hence it
s an exothermic reaction while in beaker C. heat is absorbed from water, so temperature
fals, nercA it is an endothermicprocess
, Chemical Reactions and Equations 3
Q.6 Adilute ferrous sulphate solution was gradually added to the beaker
Containing acidified permanganate solution. The light purple colour of the
solution fades and finallydisappears. Which of the following is the correct
explanation for the observation?
(a) KMnO, is an oxidising agent, it oxidises FeSO,
(b) FeSO, acts as an oxidising agent and oxidises KMnO,
(c) The colour disappears due to dilution, no reaction is involved
(d) KMnO, is an unstable compound and decomposes in the presence of FeSO, to
a colourless compound
Ans. (a) Potassium permanganate (KMnO,) in presence of dil H,SO,. i.e., in acidic medum
acts as strong oxidisingagent. In acidic medium, KMnO, oxidises ferrous sulphate to
ferric sulphate.
2KMnO, + 8H,SO, +10Fe SO, ’K,SO, + 5Fe,(SO,)+2MnSO, + 8H,0
Ferrous Ferric
sulphate sulphate
Q.7Which among the following is (are) double displacement reaction(s)?
(i) Pb + CuCl, ’ PbCl, + Cu
(ii) Na,So, + BaCl, ’ BaSO, + 2NaCL
(ii) C+ 0, ’ C0,
(iv) CH, + 20, ’ C0, + 2H,0
(a) (i) and (iv) (b) Only (ii) (c) (i) and (i) (d) (ii) and (iv)
Ans. (b) Indouble displacement reaction, two compounds exchange their ions to form two new
Compounds.
Only in reaction (ü), exchange of ions is taking place (cations and anions of both
reactants are exchanged).
Na,SO,+ BaCl, ’BaSO, + 2NaCl
White ppt
Q. 8 Which among the following statement(s) is /are true? Exposure of silver
chloride to sunlight for along duration turns grey due tß"
(i) the formation of silver by decomposition of silver chloride.
(i) sublimation of silver chloride.
(ii) decomposition of chlorine gas from silver chloride.
(iv) oxidation of silver chloride.
(a) (i) Only (b) () and (ii) (c) (ii) and(ii) (d) Only (iv)
Ans. (a) Decomposition of silver chloride takes place in the presence of sunlight.
Sunlight
2AgCi ’ 2Ag(s) +Cl,
Silver Sliver
chloride (grey)
In this reaction, the white colour of silver chloride changes greyish white due to the
formation of silver metal.
and Equations
Multiple Choice Questions (MCQs)
Q. IWhich of the following is not a physical change?
(a) Boiling of water to give water vapour
(b) Melting of ice to give water
(c) Di_solution of salt in water
d Combustion of Liquefied Petroleum Gas (LPG)
Thinking Process
)Chemical change takes place on the molecular level and it produces a new substance.
(1) Physical change involves change in physical properties and it does not produce a
new substance.
Ans. (d) Combustion of Liquefied Petroleum Gas (LPG) is a chemical change. Because it is an
irreversible reaction and new products, carbon dioxide and water vapour are formned
and lot of heat is also produced during the reaction.
Rest three are physical changes as no new products are formed.
Q.2The following reaction is an example of a
4NH, (g) + 50, (g) - 4NO (g) + 6H,0 (g)
1. displacement reaction
2. combination reaction
3. redoX reaction
4. neutralisation reaction
(a) 1and 4 (b) 2 and 3 (c) 1and 3 Va) 3 and 4
Thinking Process
In this reaction, NH, is changing into NO Removal of hydrogen froma substance is
called oxidation. So, NH, is undergoing oxidation. O, is changing into H,0 The addition
of hydrogen to a substance is called reduction. So, o, is undergoing reduction.
Ans. (d) It is a redox reaction because oxidation and reduction both take place simultaneously
in this reaction. Also, it is a displacement reaction because H of NH, has been
displaced by oxygen.
, NCERT Exemplar (Class X) Solutions
given reaction are correct?
Q. 3Which of the following statements about the
3Fe(s) + 4H,0(g) ’ Fe ,0, (s) + 4H, (g)
1. Iron metal is getting oxidised.
2. Water is getting reduced.
3. Water is acting as reducing agent.
4. Water is acting as oxidising agent.
a L2 and 3 (b) 3and 4
Ð1, 2 and 4 (d) 2 and 4
Ans. (c) Fe is gaining oxvgen to give Fe,0, H,O is losing oxygen to give H,. The substance
which UIses the other substance in a chemical reaction is known as an oxid1sing
agent. So. water is ating as oxid1sing agent.
Q. 4 Which of the following are exothermic processes?
1. Reaction of water with quick lime
2. Dilution of an acid
3. Evaporation of water
4. Sublimation of camphor (crystals)
a 1and 2 (b) 2and 3
(c) Iand 4 (d) 3 and 4
Thinking Process
ExothermIc processes are those in which heat is released along with the formation of
Ans. (a) When quick lime reacts with water, a large amount of heat is released along with the
fomationof calcium hydroOxide. Similarly, the process of dissolving an acid or base in
water s a highly exothermic reaction. Evaporation of water and sublimation of
campnor are endothermicreactions.
0.5 Three beakers labelled as A, Band Ceach containing 25 mL of water were
taken. Asmall amount of NaOH, anhydrous CuSO, and NaCl were added to
the beakers A, B and C respectively. It was observed that there was an
increase in the temperature of the solutions contained in beakers Aand B,
whereas in case of beaker C, the temperature of the solution falls. Which
one of the following statement(s) is(are) correct?
1. In beakers Aand B, exothermic process has occurred.
2. In beakers Aand B, endothermic process has occurred.
3. In beaker C, exothermic process has occurred.
4. In beaker C, endothermic process has occurred.
(a) Only 1 (b) Only2
l and 4 (d) 2 and 3
Ans. (c) ks in case of beakers Aand Bheat is given out, so temperature became high, hence it
s an exothermic reaction while in beaker C. heat is absorbed from water, so temperature
fals, nercA it is an endothermicprocess
, Chemical Reactions and Equations 3
Q.6 Adilute ferrous sulphate solution was gradually added to the beaker
Containing acidified permanganate solution. The light purple colour of the
solution fades and finallydisappears. Which of the following is the correct
explanation for the observation?
(a) KMnO, is an oxidising agent, it oxidises FeSO,
(b) FeSO, acts as an oxidising agent and oxidises KMnO,
(c) The colour disappears due to dilution, no reaction is involved
(d) KMnO, is an unstable compound and decomposes in the presence of FeSO, to
a colourless compound
Ans. (a) Potassium permanganate (KMnO,) in presence of dil H,SO,. i.e., in acidic medum
acts as strong oxidisingagent. In acidic medium, KMnO, oxidises ferrous sulphate to
ferric sulphate.
2KMnO, + 8H,SO, +10Fe SO, ’K,SO, + 5Fe,(SO,)+2MnSO, + 8H,0
Ferrous Ferric
sulphate sulphate
Q.7Which among the following is (are) double displacement reaction(s)?
(i) Pb + CuCl, ’ PbCl, + Cu
(ii) Na,So, + BaCl, ’ BaSO, + 2NaCL
(ii) C+ 0, ’ C0,
(iv) CH, + 20, ’ C0, + 2H,0
(a) (i) and (iv) (b) Only (ii) (c) (i) and (i) (d) (ii) and (iv)
Ans. (b) Indouble displacement reaction, two compounds exchange their ions to form two new
Compounds.
Only in reaction (ü), exchange of ions is taking place (cations and anions of both
reactants are exchanged).
Na,SO,+ BaCl, ’BaSO, + 2NaCl
White ppt
Q. 8 Which among the following statement(s) is /are true? Exposure of silver
chloride to sunlight for along duration turns grey due tß"
(i) the formation of silver by decomposition of silver chloride.
(i) sublimation of silver chloride.
(ii) decomposition of chlorine gas from silver chloride.
(iv) oxidation of silver chloride.
(a) (i) Only (b) () and (ii) (c) (ii) and(ii) (d) Only (iv)
Ans. (a) Decomposition of silver chloride takes place in the presence of sunlight.
Sunlight
2AgCi ’ 2Ag(s) +Cl,
Silver Sliver
chloride (grey)
In this reaction, the white colour of silver chloride changes greyish white due to the
formation of silver metal.
