Be and Mg do not react with water. This is because of:
Formation of protective oxide layer
High ionization enthalpy
High electron gain enthalpy
High enthalpy of atomization
Be and Mg are kinetically inert to water due to formation of protective oxide film on the surface of it.
BeSO4 is water soluble while CaSO4 is not. This is because of:
The element having very high ionization enthalpy but zero electron gain enthalpy is