The ionic character of the alkali metal hydrides increases from Li to Cs. Explanation: Since ionisation enthalpy of alkali metals decreases down the group, tendency to form cations as well as the ionic character of the hydrides increases.

Dear these diffrences in ionic chracter of alkaline metal hydrides are due to exceptional structural behaviour of BeH2 and MgH2

BeH2 Show this exceptional behaviour due to 3c-2e bonding.....

In alkali metal ionic character increase down the grp ,then why melting point decreases .Instead m.p should increase as ionic character increases