Consider the hydrated ions of $\mathrm{Ti}^{2+}, \mathrm{V}^{2+}, \mathrm{Ti}^{3+}$ and $\mathrm{Sc}^{3+}$. The correct order of their spin-only magnetic moments is:

(B) $\mathrm{Sc}^{3+}<\mathrm{Ti}^{3+}<\mathrm{Ti}^{2}<\mathrm{V}^{2+}$

(A) $\mathrm{Ti}^{3+}<\mathrm{T}^{2+}<\mathrm{Sc}^{3+}<\mathrm{V}^{2+}$

(C) $\mathrm{V}^{2+}<\mathrm{Ti}^{2+}<\mathrm{Ti}^{3+}<\mathrm{Sc}^{3+}$

(D) $\mathrm{Sc}^{3+}<\mathrm{Ti}^{3+}<\mathrm{V}^{2+}<\mathrm{Ti}^{2+}$

JEE Main · 2019 · 10 Apr 2019 · Shift 1 · d and f Block Elements

Consider the hydrated ions of

Ti^{2 +}, V^{2 +}, Ti^{3 +}

and

Sc^{3 +}

. The correct order of their spin-only magnetic moments is:

Answer: (B)

The spin-only moment is

μ = n (n + 2)

BM, set by the number of unpaired electrons

n

. For

Sc X^{3 +}

([Ar]

3 d^{0}

n = 0

and

μ = 0

; for

Ti X^{3 +}

(

3 d^{1}

μ = 3 \approx 1.73

; for

Ti X^{2 +}

(

3 d^{2}

μ = 8 \approx 2.83

; and for

V X^{2 +}

(

3 d^{3}

μ = 15 \approx 3.87

. The moments rise in the order

Sc X^{3 +} < Ti X^{3 +} < Ti X^{2 +} < V X^{2 +}

JEE Main · 2019 · 10 Apr 2019 · Shift 1 · Single correct option