An ionic hydride of an alkali metal has significant covalent character and is almost unreactive towards oxygen and chlorine. This is used in the synthesis of other useful hydrides. Write the formula of this hydride. Write its reaction with $Al_2Cl_6$.

(N/A) The alkali metal hydride that exhibits significant covalent character and is relatively unreactive towards oxygen and chlorine is lithium hydride,$LiH$.
It is used in the synthesis of other useful hydrides like $LiAlH_4$.
The reaction of $LiH$ with $Al_2Cl_6$ is:
$8LiH + Al_2Cl_6 \rightarrow 2LiAlH_4 + 6LiCl$.