Question

The solubilities of $Na _{2} SO _{4}, BeSO _{4}, MgSO _{4}$ and $BaSO _{4}$ will follow the order

• A. $BeSO _{4}> MgSO _{4}> Na _{2} SO _{4}> BaSO _{4}$
• B. $BeSO _{4}> Na _{2} SO _{4}> MgSO _{4}> BaSO _{4}$
• C. $MgSO _{4}> BeSO _{4}> Na _{2} SO _{4}> BaSO _{4}$
• D. $Na _{2} SO _{4}> BeSO _{4}> MgSO _{4}> BaSO _{4}$

Answer 1

Answer: (D)

Alkali metal sulphates are more soluble as compared to alkaline earth metal sulphates. Thus, $Na _{2} SO _{4}$ is most soluble.
Among alkaline earth metal sulphates, $BeSO _{4}$ is most soluble. This is because, on moving downward, the magnitude of lattice energy remains almost constant (due to large sized sulphate ion) but hydration energy decreases. Hence, the order of solubility is
$Na _{2} SO _{4}> BeSO _{4}> MgSO _{4}> BaSO _{4}$