Which alloy is used for making aircraft parts?

Which of the following are not ionic compounds?
$(i)$ $KCl$
$(ii)$ $HCl$
$(iii)$ $CCl_4$
$(iv)$ $NaCl$

A non-metal $A$, which is the largest constituent of air, when heated with $H_2$ in a $1 : 3$ ratio in the presence of a catalyst $(Fe)$, gives a gas $B$. On heating with $O_2$, it gives an oxide $C$. If this oxide is passed into water in the presence of air, it gives an acid $D$, which acts as a strong oxidising agent.
$(a)$ Identify $A$, $B$, $C$, and $D$.
$(b)$ To which group of the periodic table does this non-metal belong?

Distinguish between the following:
$(i)$ Electrolytic reduction and electrolytic refining
$(ii)$ Mineral and ore
$(iii)$ Alloys and amalgams

Write chemical equations for the reactions taking place when:
$(i)$ iron is strongly heated in air.
$(ii)$ lead carbonate is calcined.
$(iii)$ chromium oxide $(Cr_{2}O_{3})$ is heated with aluminium powder.

Which of the following reactions does $NOT$ occur during the extraction of iron in a blast furnace?