MHTCET 13 Apr 2026 Shift 1 Paper

Concept:For octahedral complexes, $\Delta_o$ depends on the ligand field strength and the oxidation state of the metal ion.Explanation:Strong field ligands like $\mathrm{CN}^-$ produce larger $\Delta_o$ than weak field ligands like $\mathrm{H_2O}$.For the same ligand, a higher metal oxidation state increases $\Delta_o$ because the metal attracts ligand electrons more strongly.Compare I and II: both contain $\mathrm{H_2O}$, but II has $\mathrm{Co}^{3+}$ while I has $\mathrm{Co}^{2+}$.Hence, $\Delta_o(\mathrm{I}) < \Delta_o(\mathrm{II})$. So option A is correct.Compare I and III: both contain $\mathrm{H_2O}$, but III has $\mathrm{Fe}^{3+}$, which has a higher oxidation state than the $\mathrm{Co}^{2+}$ in I.Therefore, $\Delta_o(\mathrm{I}) < \Delta_o(\mathrm{III})$. So option B is also correct.Compare IV with II: IV contains the strong field ligand $\mathrm{CN}^-$, while II contains the weak field ligand $\mathrm{H_2O}$.So, $\Delta_o(\mathrm{IV}) > \Delta_o(\mathrm{II})$, making option C ($\mathrm{IV} < \mathrm{II}$) incorrect.Option D is the reverse of option A, so it is also incorrect.Answer:Both A and B are correct.