Which of the following oxides of nitrogen is coloured?

Define the order of $d_{P-O}$ (single bond length) in the given compounds $X$ and $Y$:
$P_4 \xrightarrow{O_2} 'X'$
$P_4 \xrightarrow{O_2 \text{ (excess)}} 'Y'$

When a brown compound of manganese $(A)$ is treated with $HCl$,it gives a gas $(B)$. The gas taken in excess,reacts with $NH_3$ to give an explosive compound $(C)$. Identify compounds $A$,$B$,and $C$.

Reaction of thionyl chloride with white phosphorus forms a compound $[A]$,which on hydrolysis gives $[B]$,a dibasic acid. $[A]$ and $[B]$ are respectively

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

On reaction of $Lead$ $Sulphide$ with dilute nitric acid,which of the following is not formed?