Solution
Core Logic
(1) Phosphorus and Arsenic possess vacant d-orbitals. They can act as π-acceptor ligands, forming dπ-dπ backbonds with transition metals. (Correct) (2) Nitrogen (Period 2) does NOT possess vacant d-orbitals in its valence shell. Oxygen also does not have d-orbitals. Therefore, Nitrogen cannot form a dπ-pπ bond with oxygen. (Incorrect) (3) Nitrogen forms strong pπ-pπ multiple bonds with itself (e.g., in N ≡ N). (Correct) (4) Phosphorus, arsenic, and antimony exhibit catenation (e.g., P₄), although to a lesser extent than carbon. (Correct)
Step 1: Final Conclusion
Statement (2) is incorrect because nitrogen lacks d-orbitals.
Pattern Recognition
Period 2 elements (Li, Be, B, C, N, O, F) NEVER form dπ-pπ bonds using their own d-orbitals because they do not have accessible 2d orbitals.
Chapter Mix
Class 12 Chemistry: The p-Block Elements Class 11 Chemistry: Chemical Bonding and Molecular Structure