JEE Main 2026 — Chemistry Inorganic Chemistry

2026mcqmedium

Given below are two statements :

Statement I: The first ionization enthalpy of Cr is lower than that of Mn .

Statement II: The second and third ionization enthalpies of Cr are higher than those of Mn.

In the light of the above statements, choose the correct answer from the options given below :

Official previous-year question

Held on 22 Jan 2026 · Verified 6 Jul 2026.

Options

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

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Solution

Statement I:

The electronic configuration of $Cr$ is $[Ar] 3d^5 4s^1$ and $Mn$ is $[Ar] 3d^5 4s^2$ .

For $Cr$ , the first electron is removed from $4s^1$ , while for $Mn$ , it is removed from a stable fully filled $4s^2$ subshell.

Additionally, $Mn$ has a higher nuclear charge.

Thus, the first ionization enthalpy ( $IE_1$ ) of $Cr$ ( $653 \text{ kJ/mol}$ ) is lower than that of $Mn$ ( $717 \text{ kJ/mol}$ ).

Statement I is true.

Statement II:

For the second ionization enthalpy ( $IE_2$ ), $Cr^+$ has configuration $[Ar] 3d^5$ (stable half-filled) and $Mn^+$ has $[Ar] 3d^5 4s^1$ .

Removing an electron from the stable $3d^5$ configuration of $Cr^+$ requires more energy than removing it from the $4s^1$ of $Mn^+$ .

Thus, $IE_2$ of $Cr$ ( $1592 \text{ kJ/mol}$ ) is higher than $Mn$ ( $1509 \text{ kJ/mol}$ ).

For the third ionization enthalpy ( $IE_3$ ), $Cr^{2+}$ is $[Ar] 3d^4$ and $Mn^{2+}$ is $[Ar] 3d^5$ .

Removing an electron from the stable half-filled $3d^5$ configuration of $Mn^{2+}$ requires significantly more energy than from the $3d^4$ of $Cr^{2+}$ .

Thus, $IE_3$ of $Mn$ ( $3248 \text{ kJ/mol}$ ) is higher than $Cr$ ( $2987 \text{ kJ/mol}$ ).

Since $IE_3$ of $Cr$ is lower than $Mn$ , Statement II is false.

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Solution

Statement I:

The electronic configuration of $Cr$ is $[Ar] 3d^5 4s^1$ and $Mn$ is $[Ar] 3d^5 4s^2$ .

For $Cr$ , the first electron is removed from $4s^1$ , while for $Mn$ , it is removed from a stable fully filled $4s^2$ subshell.

Additionally, $Mn$ has a higher nuclear charge.

Thus, the first ionization enthalpy ( $IE_1$ ) of $Cr$ ( $653 \text{ kJ/mol}$ ) is lower than that of $Mn$ ( $717 \text{ kJ/mol}$ ).

Statement I is true.

Statement II:

For the second ionization enthalpy ( $IE_2$ ), $Cr^+$ has configuration $[Ar] 3d^5$ (stable half-filled) and $Mn^+$ has $[Ar] 3d^5 4s^1$ .

Removing an electron from the stable $3d^5$ configuration of $Cr^+$ requires more energy than removing it from the $4s^1$ of $Mn^+$ .

Thus, $IE_2$ of $Cr$ ( $1592 \text{ kJ/mol}$ ) is higher than $Mn$ ( $1509 \text{ kJ/mol}$ ).

For the third ionization enthalpy ( $IE_3$ ), $Cr^{2+}$ is $[Ar] 3d^4$ and $Mn^{2+}$ is $[Ar] 3d^5$ .

Removing an electron from the stable half-filled $3d^5$ configuration of $Mn^{2+}$ requires significantly more energy than from the $3d^4$ of $Cr^{2+}$ .

Thus, $IE_3$ of $Mn$ ( $3248 \text{ kJ/mol}$ ) is higher than $Cr$ ( $2987 \text{ kJ/mol}$ ).

Since $IE_3$ of $Cr$ is lower than $Mn$ , Statement II is false.

JEE Main 2026 — Chemistry Inorganic Chemistry

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JEE Main 2026 — Chemistry Inorganic Chemistry

Options

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Solution

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Physical Chemistry

Organic Chemistry

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