Laughing gas is prepared by heating

Two oxides of nitrogen, $NO$ and $NO_2$, react together at $253 \ K$ to form a compound of nitrogen $X$. $X$ reacts with water to yield another compound of nitrogen $Y$. The shape of the anion of $Y$ is:

Which among the following oxides of nitrogen is called nitrogen sesquioxide?

What is the $P-P-P$ bond angle in white phosphorus?

Which is an incorrect match?

In the following reaction,identify the nature of the product formed by the complete hydrolysis of the underlined atom at $R.T.$:
$\underline{N}Cl_3 + 3H_2O \longrightarrow 3HOCl + NH_3$