NEET UG 2024 — Chemistry Inorganic Chemistry

2024mcqmedium

Given below are two statements : Statement I: Both $\left[\mathrm{Co}\left(\mathrm{NH}_3\right)_6\right]^{3+}$ and $\left[\mathrm{CoF}_6\right]^{3-}$ complexes are octahedral but differ in their magnetic behaviour. Statement II: $\left[\mathrm{Co}\left(\mathrm{NH}_3\right)_6\right]^{3+}$ is diamagnetic whereas $\left[\mathrm{CoF}_6\right]^{3-}$ is paramagnetic. In the light of the above statements, choose the correct answer from the options given below:

Official previous-year question

Held on 30 Apr 2024 · Verified 9 Jul 2026.

Options

A
Both Statement I and Statement II are false
B
Statement I is true but Statement II is false
C
Statement I is false but Statement II is true
D
Both Statement I and Statement II are true

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Solution

In $\left[\mathrm{Co}\left(\mathrm{NH}_3\right)_6\right]^{3+}, \mathrm{Co}^{3+}$ ion is having $3 \mathrm{~d}^6$ configuration. Electronic configuration of $\mathrm{Co}^{3+}$ : NEET 2024 Chemistry, Coordination Compounds — solution figure 1

In presence of $\mathrm{NH}_3$ ligand, pairing of electrons takes place and it becomes diamagnetic complex ion. In presence of $\mathrm{NH}_3$ ligand : NEET 2024 Chemistry, Coordination Compounds — solution figure 2

$\therefore \quad\left[\mathrm{Co}\left(\mathrm{NH}_3\right)_6\right]^{3+}$ is octahedral with $\mathrm{d}^2 \mathrm{sp}^3$ hybridisation and it is diamagnetic in nature. In case of $\left[\mathrm{CoF}_6\right]^{3-}$ , Co is in +3 oxidation state and it is having $3 \mathrm{~d}^6$ configuration. In presence of weak field $\mathrm{F}^{-}$ ligand, pairing does not take place. In presence of $\mathrm{F}^{-}$ ligands : NEET 2024 Chemistry, Coordination Compounds — solution figure 3

$\therefore$ In $\left[\mathrm{CoF}_6\right]^{3-}, \mathrm{Co}^{3+}$ is $\mathrm{sp}^3 \mathrm{~d}^2$ hybridised with four unpaired electrons, so it is paramagnetic in nature.

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Solution

$\therefore$ In $\left[\mathrm{CoF}_6\right]^{3-}, \mathrm{Co}^{3+}$ is $\mathrm{sp}^3 \mathrm{~d}^2$ hybridised with four unpaired electrons, so it is paramagnetic in nature.

NEET UG 2024 — Chemistry Inorganic Chemistry

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NEET UG 2024 — Chemistry Inorganic Chemistry

Options

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Solution

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NEET UG Inorganic Chemistry in other years

More NEET UG Inorganic Chemistry questions

Other Chemistry topics for NEET UG

Physical Chemistry

Organic Chemistry

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