On heating compound (A) gives a gas (B) which is a constituent of air. This gas when treated with 3 moles of hydrogen $\left(\mathrm{H}_2\right)$ in the presence of a catalyst gives another gas (C) which is basic in nature. Gas $C$ on further oxidation in moist condition gives a compound (D) which is a part of acid rain. Identify compounds (A) to (D) and also give necessary equations of all the steps involved.
The main constituents of air are nitrogen (78%) and oxygen (21%). Only $\mathrm{N}_2$ reacts with three moles of $\mathrm{H}_2$ in the presence of a catalyst to give $\mathrm{NH}_3$ (ammonia) which is a gas having basic nature. On oxidation, $\mathrm{NH}_3$ gives $\mathrm{NO}_2$ which is a part of acid rain. So, the compounds $A$ to $D$ are as
$$A=\mathrm{NH}_4 \mathrm{NO}_2 ; B=\mathrm{N}_2 ; C=\mathrm{NH}_3 ; D=\mathrm{HNO}_3$$
Reactions involved can be given, as
(i) $$\mathop {N{H_4}N{O_2}}\limits_{[A]} \buildrel \Delta \over \longrightarrow \mathop {{N_2}}\limits_{[B]} + 2{H_2}O$$
(ii) $$\mathop {{N_2}}\limits_{[B]} + 3{H_2}$$ $\rightleftharpoons$ $$\mathop {2N{H_3}}\limits_{[C]} $$
(iii) $$4N{H_3} + 5{O_2}\buildrel {Oxidation} \over \longrightarrow 4NO + 6{H_2}O$$
(iv) $\mathrm{2NO+O_2 \rightarrow 2NO_2}$
(v) $$3N{O_2} + {H_2}O \to \mathop {2HN{O_3}}\limits_{[D]} + NO$$