The number of $P-OH$ bonds present in pyrophosphoric acid and hypophosphoric acid is respectively

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

Strong reducing behaviour of $H_3PO_2$ is due to

What are the products formed when ammonia reacts with excess chlorine?

Phosphorus pentoxide $(P_4O_{10})$ is used as a ........ .

When concentrated nitric acid is heated,it decomposes to give