Identify the pair of species in which the first species contains exclusively p - p multiple bonds and the second species contains d - p multiple bonds.

Step-by-step solution

Nitrogen belongs to the second period and its valence shell configuration is 2s^2 2p^3 . Since it lacks vacant d-orbitals, it can only form p - p multiple bonds (e.g., in N ₂ , NO ₂^- , NO ₃^- ). Phosphorus and sulphur belong to the third period and have vacant d-orbitals in their valence shells. Thus, they can form d - p multiple bonds with oxygen (e.g., in PO ₄³⁻ , SO ₄²⁻ ). In the given options, NO ₃^- contains exclusively p - p bonds, while PO ₄³⁻ contains d - p bonds. Therefore, the correct pair is NO ₃^- and