MHTCET 19 Apr 2026 Shift 1 Paper

Concept:The oxidation state of a metal in a complex ion is found by equating the sum of charges of the metal and ligands to the overall charge of the complex.Explanation:In $\left[\mathrm{Co}\left(\mathrm{NH}_{3}\right)_{6}\right]^{3+}$, ammonia $\left(\mathrm{NH}_{3}\right)$ is a neutral ligand, so each contributes a charge of $0$.Let the oxidation state of cobalt be $x$.The total charge of the complex is $+3$.Therefore, $x + 6(0) = +3$.This simplifies to $x = +3$.Answer:The oxidation state of cobalt is $+3$, which is Option C.