The laughing gas is

With excess of water,$PCl_5$ gives

$PbF_4$ and $PbCl_4$ exist,while $PbBr_4$ and $PbI_4$ do not exist. This is due to:

When $NH_3$ reacts with $Cl_2$,which of the following statements are correct?
$(a)$ $NCl_3$ is formed when $Cl_2$ is in excess.
$(b)$ $N_2$ is formed when $Cl_2$ is in excess.
$(c)$ $N_2$ is formed when $NH_3$ is in excess.
$(d)$ $NCl_3$ is formed when $NH_3$ is in excess.

Phosphine $(PH_3)$ is not obtained by which of the following reactions?

Which of the following acids exists in a polymeric form?