Among the following compounds,which on heating do not produce $N_2$?

Which of the phosphorus oxoacids can create a silver mirror from $AgNO_3$ solution?

Phosphorus pentachloride $(PCl_{5})$:

How can you synthesize nitric oxide $(NO)$ in the laboratory?

In the following reaction,identify the nature of the products formed by the complete hydrolysis of $\underline{P}_4O_8$ at $R.T$:
$\underline{P}_4O_8 + H_2O \longrightarrow H_3PO_3 + H_3PO_4$

Given below are the two statements: one is labeled as Assertion $(A)$ and the other is labeled as Reason $(R)$.
Assertion $(A)$: There is a considerable increase in covalent radius from $N$ to $P$. However,from $As$ to $Bi$,only a small increase in covalent radius is observed.
Reason $(R)$: Covalent and ionic radii in a particular oxidation state increase down the group.
In the light of the above statements,choose the most appropriate answer from the options given below: