JEE Main 2023 — Coordination Compounds Question with Solution
From: JEE Main 2023 (Online) 10th April Evening Shift
Question
The correct order of the number of unpaired electrons in the given complexes is
A.
B.
C.
D.
E.
Choose the correct answer from the options given below:
Choose an option
Show full solutionCorrect option: D
Step-by-step explanation
The number of unpaired electrons in a complex can be determined by the oxidation state of the central metal atom and the ligand field splitting energy. In general, a complex with a high-spin configuration will have more unpaired electrons than a complex with a low-spin configuration.
In the given complexes, the oxidation states of the central metal atoms are:
- Fe(II) in [Fe(CN)6]3-
- Fe(III) in [FeF6]3-
- Co(III) in [CoF6]3-
- Cr(III) in [Cr(ox)3]3-
- Ni(0) in [Ni(CO)4]
The ligand field splitting energy of a complex depends on the type of ligand. In general, ligands that are strong field ligands will split the d orbitals more than ligands that are weak field ligands.
The following table shows the number of unpaired electrons in each complex :
| Complex | Oxidation state | Ligand field splitting energy | Number of unpaired electrons |
|---|---|---|---|
| [Fe(CN)6]3- | Fe(II) | Low-spin | 1 |
| [FeF6]3- | Fe(III) | High-spin | 5 |
| [CoF6]3- | Co(III) | High-spin | 4 |
| [Cr(ox)3]3- | Cr(III) | High-spin | 3 |
| [Ni(CO)4] | Ni(0) | None | 0 |
Therefore, the correct order of the number of unpaired electrons in the given complexes is :
E < A < D < C < B
Practice this on the real CBT interface
Solve this JEE Main question (and the rest of the Coordination Compounds chapter) on PrepSharp's TCS iON-style CBT player — with timer, bookmarks and session analytics.
Solve interactively →About this question
This is a previous-year question from JEE Main 2023, covering the Coordination Compounds chapter of Chemistry. PrepSharp catalogues every PYQ from JEE Main with a verified answer key and step-by-step solution prepared by IIT alumni — so you can search by chapter, topic or year and revise efficiently.