(i) Among alkaline earth metal hydroxides, the anion being common the cationic radius will influence the lattice enthalpy.
Since lattice enthalpy decreases much more than the hydration enthalpy with increasing ionic size, the solubility of alkaline earth metal hydroxides in water increases down the group.
(ii) The size of anions being much larger compared to cations the lattice enthalpy will remain almost constant with in a particular group.
Since the hydration enthalpies decrease down the group, so, solubility of alkaline earth metal carbonates and sulphates in water decrease down the group.
