Find the element, which displays greater ability to form $p \pi-p \pi$ multiple bonds to itself and to other elements in the same block.

$A$ hydride of nitrogen which is acidic is

$8 NH_{3} + 3 Cl_{2} \rightarrow X$ (Excess $NH_{3}$)
$NH_{3} + 3 Cl_{2} \rightarrow Y$ (Excess $Cl_{2}$)
What are $X$ and $Y$ in the above reactions?

In the following reaction,identify the nature of the product formed by the complete hydrolysis of the underlined atom at $R.T.$:
$\underline{N}F_3 + H_2O \longrightarrow \text{No reaction}$

Which of the following oxides is least acidic?

$N_2$ forms $NCl_3$,whereas $P$ can form both $PCl_3$ and $PCl_5$. Why?