(A) In the case of nitrogen, all oxidation states from +1 to +4 tend to disproportionate in acid solution. For example. 3HNO2⟶HNO3+H2O+2NO (B) Nitrogen form pπ−pπ bonds with itself and other elements with small size and high electronegativity, dπ−pπ is not possible with itself as it has no d-orbital. (C) The single N−N bond is weaker than the single P−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.