(b) How is sodium obtained from molten sodium chloride ? Give equation of the reactions.

Sodium is obtained from sodium chloride using electrolysis. 

Following reactions are involved in the reaction:

The following equation represents the breaking apart of NaCl_(l):

2NaCl_(l) → 2Na_(l) + Cl_{2 (g)}

The half-reactions involved in this process are:

Reduction: 2Na⁺_(l) + 2e^- → Na_(s) 

Oxidation  2Cl^-_(l) → Cl_{2 (g)} + 2 e^-