Question

The solubility in water of sulphate down the Be group is Be > Mg > Ca > Sr > Ba. This is due to

(a) decreasing lattice energy

(b) high heat of solvation for smaller ions like Be²⁺

(c) increase in melting points

(d) increasing molecular weight.

Answer 1

The correct option is: (b) high heat of solvation for smaller ions like Be²⁺

Explanation:

As we move down the group from BeSO₄ to BaSO₄ the enthalpy of hydration of the positive ion becomes smaller due to increase in ionic size. Salts of heavier metal ions are less soluble than those of lighter ions.