NEET Chemistry Question (2026) — Solution

Step-by-step solution

The complex name is tetraammineaquachloridocobalt(III) chloride. The central metal ion is cobalt(III), which means Co is in the +3 oxidation state. The ligands inside the coordination sphere are four ammine ( NH _3) molecules which are neutral, one aqua ( H _2 O ) molecule which is neutral, and one chlorido ( Cl ^-) ion which has a -1 charge. The coordination sphere is [ Co ( NH _3)_4( H _2 O ) Cl ]. The charge on the complex ion is calculated as +3 + 4(0) + 0 + (-1) = +2. To balance the +2 charge of the complex ion, two chloride ( Cl ^-) counter ions are required outside the coordination sphere. Thus, the formula of the complex is [ Co ( NH _3)_4( H _2 O ) Cl ] Cl _2. Answer: [ Co(NH _3)_4( H _2 O ) Cl ] Cl _2