Among ${\text{CaH}}_2,{\text{BeH}}_2,{\text{BaH}}_2$, the order of ionic character is:

For group 2 elements, as we move down the group ($\text{Be}\to \text{Mg}\to \text{Ca}\to \text{Sr}\to \text{Ba}$), the size of the cation increases and electronegativity decreases. This leads to a decrease in polarizing power (Fajans' Rules) and an increase in the ionic character of their hydrides.Order: ${\text{BeH}}_2<{\text{CaH}}_2<{\text{BaH}}_2$.