Write in brief on
(i) ionic hydrides

Explanation

Ionic hydrides: These are formed by the highly electorpositive s-block metals. In s-block metals. In s-block metal hydrdes `LiH, BeH_(2) and MgH_(2)` have some covalent character. The ionic hydrides are crystalline. They are non-volatile compounds. They are non-volatile compounds. They are non-conducting in solid state. But in molten condition, if electrolysed they give metal at cathode and hydrogen at anode.
`CaH_(2) overset("electrolysis")(rarr) Ca + H_(2)`
This reaction confirms that ionic hydrides contain `H^(-)` ion.
Ionic hydrides liberate hydrogen forming alkaline solution when dissolved in water.
`NaH + H_(2)O rarr NaOH + H_(2)`
So ionic hydrides are used as a source of hydrogen.