Which of the following ammonium compounds yields nitrogen gas upon heating?

The cyanamide process is used in the formation of:

Extra pure $N_2$ can be obtained by heating

Which element does not show the inert pair effect?

What are $X$ and $Y$,respectively in the following reactions?
$Au + \text{aqua regia} \longrightarrow AuCl_4^{-} + H_2O + X$
$Pt + \text{aqua regia} \longrightarrow PtCl_6^{2-} + H_2O + Y$

The incorrect statement about $PH_3$ is: