MHT CET Chemistry Question (2026) — Solution

Step-by-step solution

Let the oxidation state of cobalt be x. The given coordination compound dissociates into a complex cation [ Co(NH _3)_5 Br ]^ 2+ and a sulfate anion SO _4^ 2- . The overall charge on the complex cation is +2. Ammonia ( NH _3) is a neutral ligand with an oxidation state of 0, and bromide ( Br ^-) has an oxidation state of -1. Summing the oxidation states of the central metal atom and the ligands: x + 5(0) + (-1) = +2 x - 1 = +2 x = +3 The oxidation state of cobalt in the complex is +3. Answer: +3