Which process is used to convert sulphide ores into oxides by heating them in the presence of excess air?

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?

$(i)$ Given below are the steps for the extraction of copper from its ore. Write the reactions involved:
$(a)$ Roasting of copper $(I)$ sulphide
$(b)$ Reduction of copper $(I)$ oxide with copper $(I)$ sulphide
$(c)$ Electrolytic refining
$(ii)$ Draw a neat and well-labelled diagram for the electrolytic refining of copper.

Make the correct pairs from below mentioned $X$ and $Y$:

$X$	$Y$
$1$. Extraction of sulphur	$p$. Contact process
$2$. Production of nitric acid	$q$. Frasch method
$3$. Production of sulphuric acid	$r$. Haber's process
$4$. Production of ammonia gas	$s$. Ostwald's method

An electrolytic cell consists of
$(i)$ positively charged cathode
$(ii)$ negatively charged anode
$(iii)$ positively charged anode
$(iv)$ negatively charged cathode

Give reasons for the following:
$(i)$ Metals conduct electricity.
$(ii)$ Non-metals in general do not displace hydrogen from dilute acids.
$(iii)$ Aluminium easily combines with oxygen but still it can be used for making kitchen utensils.