Choose the correct stability order of group $13$ elements in their $+1$ oxidation state.

Phosphorus pentachloride $(PCl_{5})$:

When chlorine reacts with a gas $X,$ an explosive inorganic compound $Y$ is formed. Then $X$ and $Y$ will be

Phosphorus has three allotropic forms:
$(i)$ white phosphorus
$(ii)$ red phosphorus and
$(iii)$ black phosphorus.
Write the difference between white and red phosphorus on the basis of their structure and reactivity.

Which of the following pentahalides is $NOT$ formed?

Phosphorus can be stored in