On heating, some solid substances change from solid to vapour state without passing through liquid state. The technique used for the purification of such solid substances based on the above principle is known as

Step-by-step solution

(1) Sublimation : It is the purification technique based on principle that on heating, some solid substances change from solid to vapour state without passing through liquid state. (2) Distillation : It is used to separate volatile liquids from non-volatile impurities and the liquids having sufficient difference in their boiling point. (3) Chromatography : It is based on separation by using stationary and mobile phase. (4) Crystallization : It is based on difference in the solubilities of the compound and impuritie