Co-ordination Compounds - 1 - Free MCQ Test with solutions for JEE Chemistry

The correct answer is Option C.

More basic and chelate forming ligand stabilises the complex to more extent C₂O₄²- is a bidentate chelating ligand thus stabilises the complex [Fe(C₂O₄)₃]^3- to a high extent.

Spin only magnetic moment = √(n(n+2)) B.M.

Where n = number of unpaired electron

Given, √(n(n+2)) = 2.84

n(n + 2) = 8.0656

n = 2

In an octahedral complex, for a d4 configuration in a strong field ligand, number of unpaired electrons = 2

Hence A is correct.

The correct answer is Option A.
∆о is the magnitude of splitting of d-orbitals in the octahedral field. Strong field ligands cause large splitting of d-orbitals into t2g and eg orbitals where t2g has lower energy than d-orbitals and eg has higher energy than d-orbitals.
Spectrochemical series is the series in which ligands are arranged in the order of their increasing splitting ability. The CN- ligands are at the right most end indicating the high splitting power.