If `Na^(+)` ion is larger than `Mg^(2+)` ion and `S^(2-)` ion is larger than `Cl^(-)` ion, which of the following will be least soluble in water?

Options

A. Sodium chloride
B. Sodium sulphide
C. Magnesium chloride
D. Magnesium sulphide

Answer

D

Explanation

Magnesium sulphide. Higher the lattice energy lower the solublity. Out of the four combination possible, the lattice energy of `MgS` (Bi-bivalent ionic solid) is higher than those of `Na2S, MgCl2` (uni-bivalent or biunivalent ionic solids) and `NaCl` (uniunivalent ionic solids) and hence `MgS` is the least soluble.