Name the process of change of state by which napthalene changes into vapour. Name an element that can undergo the same change of state.

Dilute hydrochloric acid is added first to a mixture of iron and sulphur and then to a compound formed by iron and sulphur. Name the gases formed in each case.

Complete the following equations and state in each case if the reaction represents oxidation or reduction :

(a) Fe²⁺ ⟶ Fe³⁺

(b) Cl^- ⟶ Cl

(c) Cu²⁺ ⟶ Cu

(d) Ag ⟶ Ag⁺

(e) H ⟶ H⁺

(f) Al ⟶ Al³⁺

Reactions can be classified as follows :

Direct combination, decomposition, simple displacement, double decomposition, redox (oxidation-reduction) reactions.

State which of the above types take place in the reactions given below :

(a) Cl₂ + 2KI ⟶ 2KCl + I₂

(b) SO₂ + 2H₂O + Cl₂ ⟶ 2HCl + H₂SO₄

(c) 4HNO₃ ⟶ 4NO₂ + 2H₂O + O₂

(d) 2Mg + O₂ ⟶ 2MgO

(e) AgNO₃ + HCl ⟶ AgCl + HNO₃