How crystallization is better than evaporation?

Q51: How crystallization is better than

evaporation? 

Answer: The process of evaporation gives residue which may contain impurities. When there is requirement to obtain solid without impurity, crystallisation method is preferred. 

In general practice, impure solids are obtained by evaporation and are further purified by crystallisation. e.g. salt obtained from sea is further purified by this method. 

In some cases e.g. sugar crystal cannot be obtained by simple evaporation technique because sugar gets charred on heating to dryness. In such cases, crystallisation technique is applied.