Which of the following is used to dry ammonia gas?

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	$(iv)$ $B_2H_6$

Which compound is formed on catalytic hydrogenation of carbon monoxide at high $p$ and high $T$ in the presence of $ZnO-Cr_2O_3$ catalyst?

The reaction of diborane in diethylether with $\underline{X}$ gives metal borohydride. $X$ is a

Explain the laboratory preparation of dihydrogen.

Which of the following pairs will not produce $H_2$ gas?