(a) Crude salt contains sodium sulphate, calcium sulphate, calcium chloride and magnesium chloride as impurities along with sodium chloride.
(b) Pure NaCl is obtained from crude salt by removal of insoluble impurities through filtration from the crude salt solution with minimum amount of water.
(c) Sodium chloride can be crystallized by passing HCl gas into this solution.
(d) Calcium and magnesium chloride being more soluble than NaCl, remain in solution.
