Which is the correct statement for the given acids?

Red phosphorus can be obtained from white phosphorus by:

$A$ tetra-atomic molecule $(A)$ on reaction with nitrogen $(I)$ oxide,produces two substances $(B)$ and $(C).$ $(B)$ is a dehydrating agent in its monomeric form while substance $(C)$ is a diatomic gas which shows almost inert behaviour. The substances $(A)$,$(B)$,and $(C)$ respectively will be

$(NH_4)_2Cr_2O_7$ on heating gives:

$Mg_3N_2(s) + H_2O \xrightarrow{R.T.} P \downarrow + Q \uparrow$. Excess $Q$ gas does not form a coloured complex with:

Concentrated $HNO_3$ is a yellow-colored liquid due to: