Exemplar Questions and Solutions

MCQs

1) Which 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)

Ans) (d) Combustion of Liquefied Petroleum Gas (LPG)

2) The following reaction is an example of a

4NH₃ (g) + 5O₂ (g) → 4NO + 6H₂O

(i) Displacement reaction

(ii) Combination reaction

(iii) Redox reaction

(iv) Neutralisation reaction

a) (i) and (iv)

b) (ii) and (iii)

c) (i) and (iii)

d) (iii) and (iv)

Ans) (d) (iii) and (iv)

3) Which of the following statements about the given reaction are correct?

3Fe (s) + 4H₂O (g) → Fe₃O₄ (s) + 4H₂ (g)

i) Iron metal is getting oxidised

ii) Water is getting reduced

iii) Water is acting as reducing agent

iv) Water is acting as oxidising agent

a) (i), (ii) and (iii)

b) (iii) and (iv)

c) (i), (ii) and (iv)

d) (ii) and (iv)

Ans) (c) (i), (ii) and (iv)

4) Which of the following are exothermic processes?

(i) Reaction of water with quick lime

(ii) Dilution of an acid

(iii) Evaporation of water

(iv) Sublimation of camphor (crystals)

(a) (i) and (ii) (b) (ii) and (iii)

(c) (i) and (iv) (d) (iii) and (iv)

Ans) (a) (i) and (ii)

5. Three beakers labelled as A, B and C each containing 25 mL of water were taken. A small amount of NaOH, anhydrous CuSO4 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 A and B, whereas in case of beaker C, the temperature of the solution falls. Which one of the following statement(s) is (are) correct?

(i) In beakers A and B, exothermic process has occurred.

(ii) In beakers A and B, endothermic process has occurred.

(iii) In beaker C exothermic process has occurred.

(iv) In beaker C endothermic process has occurred.

(a) (i) only (b) (ii) only

(c) (i) and (iv) (d) (ii) and (iii)

Ans) (c) (i) and (iv)

6. A dilute ferrous sulphate solution was gradually added to the beaker containing acidified permanganate solution. The light purple colour of the solution fades and finally disappears. Which of the following is the correct explanation for the observation?

(a) KMnO₄ is an oxidising agent, it oxidises FeSO₄

(b) FeSO₄ acts as an oxidising agent and oxidises KMnO₄

(c) The colour disappears due to dilution; no reaction is involved

(d) KMnO₄ is an unstable compound and decomposes in presence of FeSO₄ to a colourless compound.

Ans) (d) KMnO₄ is an unstable compound and decomposes in presence of FeSO₄ to a colourless compound.