Question

All hydrides of group I and group II metals decompose on heating before the melting point. True or False?

• A. True
• B. False

Answer 1

The correct option is B

False

All hydrides except LiH decompose on heating before melting point is reached. As we move down the group, although the ionic character increases, the thermal stabilities of group I and group II hydrides decreases.

Stability order is: $LiH$ $>$ $NaH$ $>$ $KH$ $>$ $RbH$ $>$ $CsH$ $>$ $Ca{H}_2$ $>$ $Sr{H}_2$ $>$ $Ba{H}_2$

LiH does not decompose before its melting point.