Is Matter Around Us Pure — Science STD 9 — Question

The mixture of common salt, sand and ammonium chloride will be heated first. Ammonium chloride sublimes on heating and can be recovered in the form of sublimate by cooling its vapours leaving behind mixture of common salt and sand. Salt is soluble in water whereas sand is insoluble in water. The mixture of sand and salt is dissolved in water, then it is filtered with the help of filter paper. Sand remains as residue on the filter paper while salt solution is obtained as filtrate .The filtrate is then evaporated to get crystals of salt.