Which of the following is an ionic hydride?

Consider the following sequence of reactions: $Na + NH_{3(g)} \to [X]$ $\xrightarrow{N_2O} [Y]$ $\xrightarrow{\text{Heat}} [Z] (\text{Gas, Pure})$. Identify $[Z]$ gas.

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

$H_2S$ reacts with $O_2$ to form:

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

High purity $(>99.95\,\%)$ dihydrogen is obtained by: