MHTCET 17 Apr 2026 Shift 1 Paper

Concept:EAN is the total number of electrons around the central metal ion in a complex.It is calculated as:$$\text{EAN} = Z - \text{oxidation state} + \text{electrons donated by ligands}$$Explanation:For cobalt, the atomic number is $Z = 27$.In $\left[\mathrm{Co}\left(\mathrm{NH}_{3}\right)_{6}\right]^{3+}$, ammonia is a neutral ligand.Thus, the oxidation state of Co is given by:$$x + 6(0) = +3$$So, $x = +3$.Each $\mathrm{NH}_{3}$ ligand donates 2 electrons.Therefore, 6 ammonia ligands donate:$$6 \times 2 = 12 \text{ electrons}$$Now, calculate EAN:$$\text{EAN} = 27 - 3 + 12$$$$\text{EAN} = 36$$Answer:The EAN of Co in $\left[\mathrm{Co}\left(\mathrm{NH}_{3}\right)_{6}\right]^{3+}$ is $36$.Correct option: C.