Which from following cations will form most stable complex with same ligand?

Step-by-step solution

The stability of coordination complexes formed by divalent transition metal ions follows the Irving-Williams series: Mn²⁺ Zn²⁺ . This trend results from decreasing ionic radii and increasing effective nuclear charge across the period, enhanced by crystal field stabilization effects. Among the given ions, Cu²⁺ exhibits the highest stability due to maximum crystal field stabilization energy among first-row transition metals and Jahn-Teller distortion effects. Final Answer: A