Question

Why is the crystallization better than evaporation to dryness?
A. Solids get charred in evaporation.
B. Solids get decomposed in evaporation.
C. Impurities do not get removed in evaporation.
 D. All of the above.

Answer 1

Hint: Evaporation is the process by which liquid changes into gas or vapors. In crystallization the chemical changes into crystals which are highly organized and non polluting substances. But in evaporation it changes into vapors and we know that some polluting substances are present in vapors.

Complete step by step answer:
> Evaporation is the process by which any element or compound changes its state from liquid state to gaseous state below the temperature at which it boils. It is an important part of the exchange of energy in the Earth-atmosphere system. The rate of evaporation depends on many factors such as temperature difference between the evaporating surface and the air, the relative humidity and also on wind.
Crystallization is the process by which a chemical is converted from liquid solution into solid crystalline state. The process of crystallization can be used for both separation and purification.
During the evaporation process solids get charred in evaporation, but during crystallization nothing like this happens. Evaporation is a surface phenomenon so it's impossible to remove all the impurities during evaporation, also sometimes solids get decomposed in evaporation.
So from above we can conclude that crystallization is better than evaporation to dryness, therefore Option D is correct.

Note: Always remember that evaporation is a surface(the phenomenon that takes place at the surface) phenomenon and crystallization is a bulk phenomenon. Due to bulk phenomenon crystallization is always better than evaporation for dryness.