The most abundant element in the universe is

How do you expect the metallic hydrides to be useful for hydrogen storage? Explain.

The hydride that is $NOT$ electron deficient is

The hydride ions $({H^{-}})$ are isoelectronic with

$LiAlH_4$ is obtained by reacting an excess of $LiH$ with an ethereal solution of $AlCl_3$. Identify the reactant that is used in excess.

What do you understand by $(i)$ electron-deficient,$(ii)$ electron-precise,and $(iii)$ electron-rich compounds of hydrogen? Provide justification with suitable examples.