MHT CET Chemistry Question (2026) — Solution

Step-by-step solution

In the given complex [ M(en) _2 C _2 O _4] Cl , the ligands present inside the coordination sphere are ethylenediamine (en) and oxalate ( C _2 O _4^ 2- ). Both ethylenediamine and oxalate are bidentate ligands. Coordination number of M = 2 2 (from en) + 1 2 (from oxalate) = 4 + 2 = 6. To find the oxidation number of M, let its oxidation state be x. The charge on ethylenediamine is 0, the charge on oxalate is -2, and the charge on the chloride ion outside the coordination sphere is -1. Equating the sum of oxidation states to the overall charge of the neutral compound: x + 2(0) + 1(-2) + 1(-1) = 0 x - 3 = 0 x = +3 The oxidation number of M is 3. Sum of coordination number and oxidation number = 6 + 3 = 9.