Magnetic moment values for $[Fe(H_2O)_6]^{3+}$ and $[Fe(CN)_6]^{3-}$ are......

5.92 BM and 1.74 respectively

The correct answer is Option (2) → 5.92 BM and 1.74 respectively

First determine the spin state of each complex.

1. $[Fe(H_2O)_6]^{3+}$

• Fe³⁺ → $d^5$
• $H_2O$ = weak field ligand
• High spin complex
• Number of unpaired electrons = 5

Magnetic moment:

$\mu = \sqrt{n(n+2)} = \sqrt{5(7)} \approx 5.92 \text{ BM}$

2. $[Fe(CN)_6]^{3-}$

• Fe³⁺ → $d^5$
• $CN^-$ = strong field ligand
• Low spin complex
• Number of unpaired electrons = 1

Magnetic moment:

$\mu = \sqrt{1(3)} \approx 1.74 \text{ BM}$

Final Answer: 5.92 BM and 1.74 respectively