Complete and balance the following equations:

(a) H₂ + ……………….. ⟶ 2HCl

(b) H₂ + S ⟶ ……………………

(c) Zn + ……………. ⟶ ZnCl₂ + H₂

(d) CuO + ………….. ⟶ Cu + ………….

(e) Fe + H₂O ⟶ …………….. + ……………

(f) K + H₂O ⟶ ……………… + ……………

Define:

(a) catalytic hydrogenation

(b) oxidation

(c) reduction

(d) redox reaction

(e) electrolysis

(f) electrolyte

Give reasons for the following:

(a) Hydrogen can be used as a fuel.

(b) Though hydrogen is lighter than air it cannot be collected by downward displacement of air.

(c) A pop sound is produced when hydrogen gas is burnt.

(d) Helium has replaced hydrogen in weather observation balloons.

(e) Nitric acid is not used for the preparation of hydrogen gas.

The chemical equation given below represents a redox reaction.

PbO (Lead monoxide) + H₂ ⟶ Pb (Lead) + H₂O

(a) Name the reactant which gets :
(i) reduced
(ii) oxidised.

(b) Which of the reactants acts as an oxidising agent ?