What is sublimation? Give its uses and examples.

(N/A) Definition: Sublimation is the process in which a solid substance changes directly into its vapour state upon heating,without passing through the liquid state.
Uses: It is used to separate sublimable organic compounds from non-sublimable impurities.
Examples: The sublimation technique is used for the purification of a mixture of $CaSO_4$ (calcium sulphate) and camphor. Camphor undergoes sublimation and is collected as a solid upon cooling,while $CaSO_4$ remains as a residue at the bottom.