Give the reaction involved during extraction of zinc from its ore by:

(a) roasting of zinc ore.
(b) calcination of zinc ore.

(a) Roasting of zinc ore: The sulphide ore of zinc ( ZnS) heated in presence of air above its melting point and convert into ZnO(s) and sulphor dioxide. The reaction is represented as:

$\text{2ZnS (s)}+2{\text{O}}_2\to \left(g\right)\stackrel{\text{Heat}}{\to }2\text{ZnO(s)}+2{\text{SO}}_2\text{(g)}$

(b) Calcination of zinc ore: The carbonate ore of zinc is heated below its melting point and absence of air to change into ZnO(s) and carbon dioxide. The reaction is represented as:

${\text{ZnCO}}_3\text{(s)}\stackrel{\text{Heat}}{\to }\text{ZnO(s)}+{\text{CO}}_2\text{(g)}$