WAEC Chemistry 2013 Paper

Concept:Water of crystallization is the fixed amount of water chemically bound inside a crystal lattice.Explanation:A hydrated salt contains water of crystallization. For example, $\mathrm{MgSO}_4 \cdot 7\mathrm{H_2O}$ is Epsom salt. $\mathrm{Na_2CO_3 \cdot 10H_2O}$ is washing soda. $\mathrm{FeSO_4 \cdot 7H_2O}$ is green vitriol. These all lose water on heating and change into anhydrous forms. Sodium chloride, $\mathrm{NaCl}$, does not form such a hydrated salt. It crystallizes directly as anhydrous sodium chloride without including any water molecules in its crystal lattice.Answer:C. $\mathrm{NaCl}$