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Indian Forest Service (Mains)

Chemistry optional

  • 2 papers
  • 200 marks each
  • 3 h per paper

Paper I covers physical and inorganic chemistry.

Indian Forest Service (Mains), Chemistry optional · 2022 · Paper I

Q6(c)(ii). Magnetism of octahedral and tetrahedral Ni(II)

Question

Calculate the spin-only magnetic moment for Ni²⁺ (d⁸) in octahedral and tetrahedral complexes. In which case is the experimental value expected to be much higher than the calculated spin-only value? Give reasons.

Answer in brief

Both geometries have two unpaired electrons, so μso = √8 = 2.83 μB; tetrahedral Ni(II) usually shows the larger excess orbital contribution.

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Topic notes: crystal field theory, with every Civil Services, IFoS and Geo-Scientist PYQ →

Coversspin-only magnetic momentNi(II) complexesorbital contributionoctahedral vs tetrahedralquenching of orbital angular momentum

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