Among $\mathrm{Co}^{3+}$, $\mathrm{Ti}^{2+}$, $\mathrm{V}^{2+}$ and $\mathrm{Cr}^{2+}$ ions, one if used as a reagent cannot liberate $\mathrm{H}_{2}$ from dilute mineral acid solution, its spin-only magnetic moment in gaseous state is _____ B.M. (Nearest integer)

JEE Main · 2022 · 25 Jul 2022 · Shift 1 · d and f Block Elements

Among

Co^{3 +}

Ti^{2 +}

V^{2 +}

and

Cr^{2 +}

ions, one if used as a reagent cannot liberate

H_{2}

from dilute mineral acid solution, its spin-only magnetic moment in gaseous state is _____ B.M. (Nearest integer)

Answer: 5

To liberate

H X_{2}

from dilute acid, the metal ion must be a reducing agent (able to donate electrons).

Co X^{3 +}

is a strong oxidizing agent and cannot reduce

H X^{+}

H X_{2}

, so it cannot liberate hydrogen.

Co X^{3 +}

has electronic configuration

d^{6}

(in gaseous state, high-spin). With 4 unpaired electrons:

μ = n (n + 2) = 4 (4 + 2) = 24 = 4.90

B.M.

Nearest integer: 5 B.M.

JEE Main · 2022 · 25 Jul 2022 · Shift 1 · Integer answer