An ionic hydride of an alkali metal has significant covalent character and is almost unreactive towards oxygen and chlorine . This is used in the synthesisi of other useful hydrides. Write the formula of this is used in the synthesis of other hydrides. Write the formula of this hydride. Write its reaction with `Al_(2)Cl_(6)`.

Explanation

Since an ionic hydride of an alkali metal has significant covalent character, therefore, the hydride will be of the smallest alkali metal (Li) , i.e., LiH, Since LiH is very stable, therefore, it is almost unreactive towards `O_(2) and Cl_(2)`
It reacts with `Al_(2)Cl_(6)` to form lithium aluminium hydride.
`8LiH + Al_(2)Cl_(6) to 2LiAlH_(4) + 6LiCl`.