Which method,other than the Contact process,is used for the production of sulfuric acid?

What is the shape of rhombic sulphur?

Metals are refined by using different methods. Which of the following metals are refined by electrolytic refining?
$(i)$ $Au$
$(ii)$ $Cu$
$(iii)$ $Na$
$(iv)$ $K$

Name one metal and one non-metal that exist in liquid state at room temperature. Also,name two metals having a melting point less than $310\ K$ $(37\ ^\circ C)$.

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?

Which catalyst is used in the industrial manufacture of hydrogen gas?