Which among the following group-$15$ elements forms hydrogen bonding in its hydride compounds?

Which of the following statements regarding $N_2O_4$ is not correct?

$H_3PO_2$ $\xrightarrow{140^{\circ}C}$ $A$ $\xrightarrow{250^{\circ}C}$ $B$ $\xrightarrow{316^{\circ}C}$ $C$
Compound $(C)$ is

$NH_3 + O_2 \xrightarrow[500 \ K]{Pt} W + H_2O$
$W + O_2 \rightleftharpoons X$
$X + H_2O \rightleftharpoons Y + W$
Which of the following statements is correct?

Which of the following oxides of nitrogen is the anhydride of nitrous acid?

State the oxoacids of phosphorus with their formula,methods of preparation,and the presence of characteristic bonds in their structure.