Use mu = sqrtn(n+2) BM. Cyanide is a strong-field ligand, so [Fe(CN)6]^3- is low spin. Its spin-only magnetic moment is

JEE Main levelSingle correct optionDifficulty 2 of 3cc023

Use $μ = n (n + 2)$ BM. Cyanide is a strong-field ligand, so $[Fe (CN) X_{6}] X^{3 -}$ is low spin. Its spin-only magnetic moment is

Fe is

+ 3

(

d^{5}

). In the low spin case all five electrons go into

t_{2 g}

t_{2 g}^{5}

, leaving

n = 1

unpaired electron.

μ = 1 \times 3 = 1.73

BM.