We analyze each complex using oxidation state, ligand strength and crystal field theory.
A. [Co(NH3)6]3+
Oxidation state of Co = +3 → electronic configuration = d6.
NH3 is a medium field ligand and Co3+ has high pairing energy.
Electrons pair in 3d orbitals.
Hybridization = d2sp3 (inner orbital complex).
Statement A is correct.
B. [MnCl6]3−
Oxidation state of Mn = +3 → electronic configuration = d4.
Cl− is a weak field ligand.
No pairing occurs; electrons remain unpaired.
Hybridization = sp3d2 (outer orbital complex).
Statement B is correct.
C. [CoF6]3−
Oxidation state of Co = +3 → d6.
F− is a weak field ligand.
This gives sp3d2 hybridization, not d2sp3.
Statement C is incorrect.
D. [FeF6]3−
Oxidation state of Fe = +3 → d5.
F− is weak field → no pairing.
Hybridization = sp3d2 (outer orbital complex).
Statement D is correct.
E. [Ni(CN)4]2−
Oxidation state of Ni = +2 → d8.
CN− is a strong field ligand.
This complex is square planar with dsp2 hybridization, not sp3.
Statement E is incorrect.
Hence, the correct set is A, B & D only.
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