AIPMT 2010 Physics and Chemistry Paper

Hydration energy varies inversely with size and in sulphates of alkaline earth metals lattice energy remains almost constant. The order of size of alkaline earth metals is
Be2+<Ca2+<Sr2+<Ba2+
Thus, the order of hydration energy is
Be2+>Ca2+>Sr2+>Ba2+
Hence, BeSO4 has the hydration enthalpy higher than the lattice enthalpy.