JEE Main 2026 — Jan 22, Shift 2 — Chemistry solution

JEE Main2026Jan 22, Shift 2Chemistry

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 :

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

Solution

Configurations: $C r = [A r] 3 d^{5} 4 s^{1}$ (half-filled $d$ , single $4 s$ electron) and $M n = [A r] 3 d^{5} 4 s^{2}$ .

$I E_{1}$ : Removing one $4 s$ electron from Cr is easier than removing one from the paired $4 s^{2}$ in Mn, so $I E_{1} (C r) < I E_{1} (M n)$ . Statement-I is correct.

$I E_{2}$ : For Cr, removal of the second electron disrupts the stable half-filled $d^{5}$ (since $C r^{+}$ is $3 d^{5}$ ), so $I E_{2} (C r) > I E_{2} (M n)$ . However, $I E_{3} (C r) < I E_{3} (M n)$ because $M n^{2 +}$ has a stable $3 d^{5}$ configuration whereas $C r^{2 +}$ does not. Statement-II is not entirely correct.

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