When Conc. $H_2SO_4$ is added to charcoal :-

Among the elements of group $16$,which element exists in a metallic lattice in its monoatomic state and also exhibits two crystalline forms,$\alpha$ and $\beta$?

Excess of $PCl_{5}$ reacts with conc $H_{2}SO_{4}$ to give:

Which among the following $P$-block elements forms a colourless and odourless hydride?

Bleaching action of $SO_2$ is due to its

What is the number of allotropes of selenium?