Suggest a method to purify : (i) Camphor containing traces of common salt.
(ii) Kerosene oil containing water.
(iii) A liquid which decomposes at its boiling point.

Explanation

(i) Sublimation. Camphor sublimes while common salt remains as residue in the china dish.
(ii) Since the two liquids are immiscible, the technique of solvent extraction with a separating funnel is used. The mixture is thoroughly shaken and the separating funnel is allowed to stand. Kerosene being lighter tha water forms the upper layer while forms the layer. The lower water layer is run off when kerosene oil is obtained. It is dried over anhydrous `CaCl_(2)` or `MgSO_(4)` and then distilled to give pure kerosene oil.
(iii) Distillation under reduced pressure. Since the b.p. of a liquid depends upon the pressure acting on it. Therefore, a liquid which decomposes at its b.p. can be purified safely at a lower temperature if the pressure acting on it reduced.