JEE Main · 2024 · 04 Apr 2024 · Shift 2 · d and f Block Elements

A first row transition metal in its +2 oxidation state has a spin-only magnetic moment value of 3.86 BM. The atomic number of the metal is

Answer: (D)

Solution

Spin-only magnetic moment:

μ = n (n + 2)

BM. Setting

n (n + 2) = 3.86

gives

n = 3

(since

3 \times 5 = 15 \approx 3.87

).
Three unpaired electrons in a

+ 2

ion of a first-row transition metal corresponds to a

d^{3}

configuration, i.e.

V^{2 +}

(

[A r] 3 d^{3}

), atomic number 23. (Ti

^{2 +}

d^{2}

, Mn

^{2 +}

d^{5}

, Fe

^{2 +}

d^{6}

JEE Main · 2024 · 04 Apr 2024 · Shift 2 · Single correct option