Solubility of an ionic compound in water is mainly dependent on:
a.Lattice enthalpy , b. Hydration enthalphy
Both these factors oppose each other and the resultant of these determines the solubility of an ionic compound in water. If lattce enthalpy has greater value, the compound is less soluble.
In case hydration enthalpy has greater value, the compound is highly soluble in water.
Compound of alkaline earth metals are less soluble than alkali metals, due to:

Options

A. Their high hydration enthalpy
B. Their high lattice enthalpy
C. Their increases covalent character
D. Their high ionisation enthalpy.

Answer

B

Explanation

Alkaline earth metal compounds `MX_(2)` have `M^(2)` ion which have more charge and smaller size as compared to alkali metal compound `MX` having `M^(o+)` ion hence lattice enthalpy of `MX` is less than `MX_(2)`.
Lattice enthalpy `prop(1)/(r_(o+)r_(Θ))`