how to solve? ans is option 3
I think it was in jee mains 2016
-The ligand, No. of ligand, and oxidation no. is the same but central atoms are different.
A central atom which have more Φ value, Δ will be more.
-The oxidation no. is more then Δ will be more. (Other are the same- ligand, no of ligand etc.)