JEE Main 2023 — Chemistry Inorganic Chemistry

2023integermedium

The d-electronic configuration of ${[{\mathrm{CoCl}}_{4}]}^{2-}$ in tetrahedral crystal field is ${e}^{m}{t}_{2}^{n}$ . The sum of $m$ and number of unpaired electrons is

Official previous-year question

Held on 24 Jan 2023 · Verified 6 Jul 2026.

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Solution

The oxidation state of Co in complex ${[{\mathrm{CoCl}}_{4}]}^{2-}$ is

$x-4=-2$

$x=+2$

Electronic configuration of $Co$ is $C27o=[Ar]4{s}^{2}3{d}^{7}$

So, $C{o}^{+2}=[\mathrm{Ar}]3{d}^{7}$

JEE Main 2023 Chemistry, Coordination Compounds — solution figure 1

Since ${\mathrm{Cl}}^{-}$ is a weak field ligand, so the given complex will have a tetrahedral geometry with following Crystal-field splitting

JEE Main 2023 Chemistry, Coordination Compounds — solution figure 2

So, value of $(m)+$ (unpaired electrons) is $(4)+(3)=7$ .

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JEE Main Inorganic Chemistry in other years

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JEE Main 2023 — Chemistry Inorganic Chemistry

2023integermedium

The d-electronic configuration of ${[{\mathrm{CoCl}}_{4}]}^{2-}$ in tetrahedral crystal field is ${e}^{m}{t}_{2}^{n}$ . The sum of $m$ and number of unpaired electrons is

Official previous-year question

Held on 24 Jan 2023 · Verified 6 Jul 2026.

Did you get this right?

Solution

The oxidation state of Co in complex ${[{\mathrm{CoCl}}_{4}]}^{2-}$ is

$x-4=-2$

$x=+2$

Electronic configuration of $Co$ is $C27o=[Ar]4{s}^{2}3{d}^{7}$

So, $C{o}^{+2}=[\mathrm{Ar}]3{d}^{7}$

JEE Main 2023 Chemistry, Coordination Compounds — solution figure 1

Since ${\mathrm{Cl}}^{-}$ is a weak field ligand, so the given complex will have a tetrahedral geometry with following Crystal-field splitting

JEE Main 2023 Chemistry, Coordination Compounds — solution figure 2

So, value of $(m)+$ (unpaired electrons) is $(4)+(3)=7$ .

Your note

JEE Main Inorganic Chemistry in other years

Keep practicing Inorganic Chemistry

Work through every JEE Main Inorganic Chemistry PYQ, year by year.

Browse all Chemistry topics

JEE Main 2023 — Chemistry Inorganic Chemistry

Did you get this right?

Solution

Your note

JEE Main Inorganic Chemistry in other years

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Other Chemistry topics for JEE Main

Physical Chemistry

Organic Chemistry

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JEE Main 2023 — Chemistry Inorganic Chemistry

Did you get this right?

Solution

Your note

JEE Main Inorganic Chemistry in other years

More JEE Main Inorganic Chemistry questions

Other Chemistry topics for JEE Main

Physical Chemistry

Organic Chemistry

Keep practicing Inorganic Chemistry