$Y$ in the given sequence of reactions is
$P_4 + x NaOH + y H_2O \xrightarrow{CO_2} X + z NaH_2PO_2$
$X + CuSO_4 \rightarrow Y + H_2SO_4$

Due to $p\pi - p\pi$ bonding interactions, nitrogen forms $N_2$ but phosphorus forms $X$ and does not form a diatomic molecule. Identify $X$.

Given below are two statements:
Statement $I$: Like nitrogen that can form ammonia,arsenic can form arsine.
Statement $II$: Antimony cannot form antimony pentoxide.
In the light of the above statements,choose the most appropriate answer from the options given below:

At what temperature is white phosphorus heated to obtain red phosphorus (in $K$)?

How many isotopes of nitrogen gas are stable? Which are they?

The reaction of $P_4$ with $X$ leads selectively to $P_4O_6$. The $X$ is