The possible oxidation states of $Tl$ are

Nitrogen forms $N_2$,but phosphorus prefers to exist as $P_4$ rather than $P_2$. Which of the following is the reason for this?

Which of the following compounds will not give $NH_3$ on heating?

Which of the following is a cyclic phosphate?

In the following reaction,identify the nature of the product formed by the complete hydrolysis of the underlined atom at $R.T.$:
$\underline{P}Cl_5 + H_2O \longrightarrow H_3PO_4 + HCl$

In the nitrogen group,as we move from $N$ to $Sb$,the $H-M-H$ bond angle in the hydrides approaches $90^o$ because ......