Complete the reaction: $8LiH + Al_2Cl_6 \to ?$

Hydrogen resembles in many of its properties

The isotopes of hydrogen are

Action of water or dilute mineral acids on metals can give

Match the following types of hydrides in List-$I$ with their examples in List-$II$.

List-$I$ (Type of hydride)	List-$II$ (Example)
$(A)$ Electron precise	$(i)$ $SiH_4$
$(B)$ Saline	$(ii)$ $H_2O$
$(C)$ Electron deficient	$(iii)$ $MgH_2$
$(D)$ Electron rich	$(iv)$ $B_2H_6$

What do you understand by the term "non-stoichiometric hydrides"? Do you expect this type of the hydrides to be formed by alkali metals? Justify your answer.