Chemistry - Coordination Chemistry Question with Solution | TestHub

Option A is incorrect: The Effective Atomic Number (EAN) for Compound-I (Fe³⁺) is $26-3+12=35$ (does not follow the rule), while for Compound-II (Fe²⁺) it is $26-2+12=36$ (follows the rule).

Option B is incorrect: Due to the strong field CN⁻ ligand, Fe³⁺ ($d^5$) pairs up to leave one unpaired electron (paramagnetic), while Fe²⁺ ($d^6$) pairs completely with zero unpaired electrons (diamagnetic).

Option C is correct: Both central ions undergo inner orbital pairing, utilizing empty $3d$ orbitals to form $d^{2}s{p}^3$ hybridization.

Option D is correct: Compound-I is more stable than Compound-II because Fe³⁺ has a higher positive charge density, leading to stronger electrostatic attraction with the ligands.