The correct order of the solubility of alkaline-earth metal sulphates in water is :

$\mathrm{Mg}>\mathrm{Sr}>\mathrm{Ca}>\mathrm{Ba}$ is the proper order of the alkaline-earth metal sulphates' solubility in water.

Alkaline earth metal sulphate is less soluble in water as the atomic number increases.

Moving down the group causes a considerably greater loss in hydration energy than lattice energy.