Which of the following orders regarding the stability of phosphorus allotropes is correct?

White phosphorus is heated with concentrated $NaOH$ in $CO_2$ atmosphere to form a gas $A$ and compound $B$. When $A$ is bubbled into aqueous $CuSO_4$ solution,copper phosphide and $C$ are formed. $B$ and $C$ are respectively:

Which of the following compounds can exist?

Give an example to show the effect of concentration of nitric acid on the formation of oxidation products.

$P_2O_3 + H_2O \rightarrow X$
$Red \ P_4 + \text{alkali} \rightarrow Y$
$X$ and $Y$ are oxoacids of phosphorus. The number of $P-OH$ bonds in $X$ and $Y$ respectively is:

Each of the following is true for white and red phosphorus except that they