JEE Main 2021 — Chemistry Inorganic Chemistry

2021mcqmedium

Identify the element for which electronic configuration in $+3$ oxidation state is $[\mathrm{Ar}]3{d}^{5}:$

Official previous-year question

Held on 1 Sept 2021 · Verified 6 Jul 2026.

Options

A
$\mathrm{Ru}$
B
$\mathrm{Mn}$
C
$\mathrm{Co}$
D
$\mathrm{Fe}$

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Solution

${\mathrm{Fe}26}^{3+}=3{d}^{5}4{s}^{0}$

$27{\mathrm{Co}}^{3+}=3{d}^{6}4{s}^{0}$

${\mathrm{Cr}24}^{3+}=3{d}^{3}4{s}^{0}$

$25{\mathrm{Mn}}^{3+}=3{d}^{4}4{s}^{0}$

${M}^{+3}=[18\mathrm{Ar}]3{d}^{5}4{s}^{0}$

$M=[\mathrm{Ar}18]3{d}^{6}4{s}^{2}$

so $Z$ for $M=26$ and $M$ is $Fe.$

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JEE Main Inorganic Chemistry in other years

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JEE Main 2021 — Chemistry Inorganic Chemistry

2021mcqmedium

Identify the element for which electronic configuration in $+3$ oxidation state is $[\mathrm{Ar}]3{d}^{5}:$

Official previous-year question

Held on 1 Sept 2021 · Verified 6 Jul 2026.

Options

A
$\mathrm{Ru}$
B
$\mathrm{Mn}$
C
$\mathrm{Co}$
D
$\mathrm{Fe}$

Did you get this right?

Solution

${\mathrm{Fe}26}^{3+}=3{d}^{5}4{s}^{0}$

$27{\mathrm{Co}}^{3+}=3{d}^{6}4{s}^{0}$

${\mathrm{Cr}24}^{3+}=3{d}^{3}4{s}^{0}$

$25{\mathrm{Mn}}^{3+}=3{d}^{4}4{s}^{0}$

${M}^{+3}=[18\mathrm{Ar}]3{d}^{5}4{s}^{0}$

$M=[\mathrm{Ar}18]3{d}^{6}4{s}^{2}$

so $Z$ for $M=26$ and $M$ is $Fe.$

Your note

JEE Main Inorganic Chemistry in other years

Keep practicing Inorganic Chemistry

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

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JEE Main 2021 — Chemistry Inorganic Chemistry

Options

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

JEE Main 2021 — Chemistry Inorganic Chemistry

Options

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