What happens when $PCl_{5}$ is heated?

Given below are two statements:
Statement $I$: The $N-N$ single bond is weaker and longer than the $P-P$ single bond.
Statement $II$: Compounds of group $15$ elements in $+3$ oxidation state readily undergo disproportionation reactions.
In the light of the above statements,choose the correct answer from the options given below:

The $15^{th}$ group of the periodic table contains elements $N, P, As, Sb,$ and $Bi$. As we move from $N$ to $Bi$,how do the oxides with the general formula $E_2O_3$ behave?

Which of the following allotropes of phosphorus is the most stable?

Pure concentrated $HNO_3$ makes iron passive as the surface is covered with a protective layer of:

In an Ostwald process:
$NH_3 + O_2 \xrightarrow[Pt]{\Delta} x + H_2O$
$x + O_2 \to y$
$y + H_2O (excess) \to x + z$
The incorrect option is: