When a mixture of common salt and ammonium chloride is heated, it is observed that:
Ammonium chloride, anthracene, napthalene can sublime but common salt cannot sublime. Ammonium chloride evaportaes and forms vapours which rise up the funnel and get deposited in the cooler parts of the funnel. Sodium chloride remains in the china dish as no reaction takes place.
Sublimation is the transition of a
substance directly from the solid to the gas phase without passing through the
intermediate liquid phase.
Hence option C is correct.