$Sn$ is dissolved in excess of $NaOH$ solution,the compound obtained is

The atomicity of phosphorus is $X$ and the $P-P-P$ bond angle in the molecule is $Y$. What are $X$ and $Y$?

On heating ammonium dichromate,the gas evolved is

The oxides of nitrogen obtained by the reaction of nitric acid with $(i)$ $P_4O_{10}$ and $(ii)$ $P_4$ respectively are:

Extra pure $N_2$ can be obtained by heating :-

$A$ colourless,neutral,paramagnetic oxide of nitrogen '$P$' on oxidation gives reddish brown gas $Q$. $Q$ on cooling gives colourless gas $R$. $R$ on reaction with $P$ gives blue solid $S$. Identify $P, Q, R, S$ respectively.