Which one of the following alkaline earth metal sulphates has its hydration enthalpy greater than its lattice enthalpy?

Options

A. `CaSO_(4)`
B. `BeSO_(4)`
C. `BaSO_(4)`
D. `SrSO_(4)`

Answer

B, C, D

Explanation

As we move down the group, size of metal increases. Be has lower size while `SO_(2-)` has bigger size, that's why `BeSO_(4)` breaks easily and lattice energy becomes smaller but due to lower size of `Be`, water molecules are gathered around and hence hydration energy increases on the other hand, rest of the metals, i.e. `Ca, Ba, Sr` have bigger size and that's why lattice energy is greater than hydration energy.
Time Saving Technique : In the question of finding hydration energy only check the size of atom. Smaller sized atom has more hydration energy. Thus, in this question `Be` is placed upper most in the group has lesser size and not comparable with the size of sulphates. Hene, `BeSO_(4)` is the right response.