Most compounds of nitrogen and phosphorus are of which type?

Nitrogen and phosphorus are non-metallic elements in Group 15 (V group) of the periodic table. Both elements have five valence electrons, and they primarily form covalent compounds by sharing electrons with other non-metals to complete their octet.

Nitrogen compounds:
Nitrogen forms a wide variety of covalent compounds, including ammonia (NH₃), nitrogen trichloride (NCl₃), nitric acid (HNO₃), and nitrous oxide (N₂O). In these compounds, nitrogen shares electrons with hydrogen, oxygen, or other non-metal atoms. The resulting molecules can be polar, but the bonds themselves are covalent.

Phosphorus compounds:
Phosphorus also forms covalent compounds like phosphine (PH₃), phosphorus pentachloride (PCl₅), phosphoric acid (H₃PO₄), and phosphorus trichloride (PCl₃). These compounds involve sharing of electrons between phosphorus and other non-metal atoms. Phosphorus rarely forms purely ionic compounds because it is not metallic enough to completely transfer electrons.

The predominance of covalent bonding is due to the high ionization energy of nitrogen and phosphorus, which makes the complete transfer of electrons (as in ionic compounds) energetically unfavorable. Additionally, the small size of nitrogen allows it to form multiple bonds such as double and triple bonds (e.g., N₂, NO₂). Phosphorus, being larger, prefers single covalent bonds but can also expand its octet in compounds like PCl₅ and PF₅.

Although some compounds may exhibit polarity or partial ionic character, the majority of nitrogen and phosphorus compounds are covalent in structure. This covalent nature contributes to their reactivity, molecular geometry, and use in fertilizers, explosives, and industrial chemicals.

Hence, the correct answer is Covalent (B)