JEE Advanced 2015 · Paper 1 · Chemistry Q24

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ChemistryInteger+4Question 24 of 60

For the octahedral complexes of $\ce{Fe^{3+}}$ in $\ce{SCN-}$ (thiocyanato-S) and in $\ce{CN-}$ ligand environments, the difference between the spin-only magnetic moments in Bohr magnetons (when approximated to the nearest integer) is

[Atomic number of Fe = 26]

Your answer

Answer and worked solution

Official answer: 4

Fe³⁺ is $d^5$ .

Thiocyanato-S (weak field): high spin, 5 unpaired, $\mu=\sqrt{35}=5.92$ BM.
Cyanide (strong field): low spin, 1 unpaired, $\mu=\sqrt3=1.73$ BM.

Difference. $4.19\approx4$ .

Answer: 4

Topics:Magnetic properties and colour Crystal field theory

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JEE Advanced 2015 · Paper 1, Chemistry question 24