A boy buys common salt from the market which is contaminated with Ammonium Chloride (NH4Cl) and sand

A boy buys common salt from the market which is contaminated with Ammonium Chloride (NH4Cl) and sand. 

The procedure he should adopt to obtain pure NaCl is the following : 

(a) to mix the sample in water and evaporate the solution

(b) to mix the sample in water and evaporate the decanted solution

(c) to mix the sample in acetone and evaporate the decanted solution 

(d) to heat the sample, then mix in water and evaporate the decanted solution 

Answer: (d) to heat the sample, then mix in water and evaporate the decanted solution Ammonium chloride sublimes, it can be separated from the mixture of salt and sand by sublimation method. 

Sand can be separated from the mixture of sand and salt by dissolving salt in water and then by filtration. Salt can be separated through the process of evaporation