Name the classes of hydrides to which $H_2O$,$B_2H_6$ and $NaH$ belong.

The highest industrial consumption of molecular hydrogen is to produce compounds of element ...... .

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	$(iv)$ $B_2H_6$

Atomic hydrogen combines with almost all elements but molecular hydrogen does not. Explain.

Which one of the following statements is not correct for ortho and para hydrogen?

Calcium imide on hydrolysis will give gas $(B)$ which on oxidation by bleaching powder gives gas $(C)$. Gas $(C)$ on reaction with magnesium gives compound $(D)$. $(D)$ on hydrolysis gives again gas $(B)$. $(B)$,$(C)$ and $(D)$ are