The property of the alkaline earth metals that increases with their atomic number is

The solubility of the ionic compounds (in this case is hydroxide of alkaline earth metals ) depends on two factors, which are (i) lattice energy and (ii) hydration energy. The lattice energy decreases more down the group as compare to the hydration energy. Hence, solubility of alkaline earth metal increases with increase in their atomic number. Whereas, other given properties i.e. ionisation energy, electronegativity and solubility of their sulphate in water decreases with atomic number.