Question

BeO is insoluble in water while BeSO4 is water soluble.

Answer 1

because beryllium oxide hydrates and gives hydroxide and hydrogen ions which react and neutralizes other and therefore random oxide is soluble in water whereas there is no such case in beryllium sulphate and therefore is it is insoluble in water

Answer 2

 BeO is almost insoluble in water andBeSO4 is soluble in water because Be2+ is a small cation with a high polarising power and O2� is a small anion.

When BeO is dissolvedin water, the hydration energy of its ions is not sufficient to overcome the high lattice energy. Therefore, BeO is insoluble in water.