Answer:
The complex ion that contains a central ion with an oxidation state of +3 is D. [Co(NH3)4Cl₂]*.
Step-by-step explanation:
The oxidation state of an atom in a compound is a measure of the number of electrons that an atom has gained or lost in a chemical reaction. The oxidation state of the central ion in a complex ion is determined by the number of electrons it donates to the ligands (atoms, ions, or molecules that are bonded to the central ion) in the complex ion.In the complex ion D. [Co(NH3)4Cl₂]*, the central ion is cobalt, which has an oxidation state of +3. This is because cobalt donates 3 electrons to the ligands in the complex ion, which are the four ammonia molecules (NH3) and the two chlorine ions (Cl2).The other complex ions listed do not contain a central ion with an oxidation state of +3. In complex ion A. [PtCl6]2-, the central ion is platinum, which has an oxidation state of +4. In complex ion B. [Cu(H₂O)4(OH)₂], the central ion is copper, which has an oxidation state of +2. Finally, in complex ion C. [Ni(NH3),(H2O)]*, the central ion is nickel, which has an oxidation state of +2.