In a coordination entity the central atoms or ions are referred to as:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → Lewis acid
In a coordination entity, the ligands donate electron pairs to the central atom or ion, which accepts them into its vacant orbitals. An electron pair acceptor is a Lewis acid (and an electron pair donor is a Lewis base). So the central atoms/ions are referred to as Lewis acids; for example, in \( \ce{[Ni(CO)4]} \) and \( \ce{[Co(NH3)6]^3+} \), Ni and \( \ce{Co^3+} \) accept electron pairs from CO and \( \ce{NH3} \).
NCERT (2026-27 edition):
Central Atom/Ion
Note: The same/similar question has been asked in different years by NTA as per the details given below:
| 2026 | 2025 | 2024 | 2023 | 2022 |
|---|---|---|---|---|
| – | – | 29-05 S1 | 08-06 S3 | – |