Suggest a method for the purification of camphor contaminated with salt.

State whether the following statements are True or False:
$(i)$ The purification of a solid is done by crystallisation.
$(ii)$ Crystallisation purifies the solid and distillation purifies the liquid.
$(iii)$ $A$ liquid is purified by sublimation.
$(iv)$ To separate a mixture of ammonium chloride and sodium chloride,the distillation method is applied.

Chromatography is used for the purification of which of the following?

Which method is used to separate glycerol from spent lye in the soap industry?

Which two organic compounds are purified by the sublimation technique?

Give a brief description of the principles of the following techniques taking an example in each case.
$(a)$ Crystallisation
$(b)$ Distillation
$(c)$ Chromatography