p Block Elements Part 3

(A) In the case of nitrogen, all oxidation states from +1 to +4 tend to disproportionate in acid solution. For example.
$3{\mathit{H}\mathit{N}\mathit{O}}_2⟶{\mathit{H}\mathit{N}\mathit{O}}_3+{\mathit{H}}_2\mathrm{O}+2\mathrm{NO}$
(B) Nitrogen form ${\mathit{p}}_{\mathit{\pi }}-{\mathit{p}}_{\mathit{\pi }}$ bonds with itself and other elements with small size and high electronegativity, ${\mathit{d}}_{\mathit{\pi }}-{\mathit{p}}_{\mathit{\pi }}$ is not possible with itself as it has no d-orbital.
(C) The single $\mathrm{N}-\mathrm{N}$ bond is weaker than the single $\mathrm{P}-\mathrm{P}$ bond because of high intereelecronic repulsion of the non-bonding electrons (lone pair), owing to the small bond length.
(D) Nitrogen has lowest density in its group.
(E) The maximum covalency of nitrogen is four.