The oxidation and coordination numbers of cobalt in the compound [Co(NH₃)₅Cl]Cl₂ are, respectively: A) 2 and 6. B) 2 and 8. C) 3 and 6. D) 3 and 8. E) None of these choices is correct.

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To determine the oxidation state of cobalt, we look at the charge of the ligands and the overall charge of the complex. - Each sulfide (S) ion has a charge of -2. There are two sulfide ions, so the total charge contributed by sulfide ions is -4. - The chloride ion (Cl) has a charge of -1. There is one chloride ion, so the total charge contributed by chloride ions is -1. - The ligand NH₃ has a neutral charge (since it is a derivative of a neutral molecule). - Therefore, the total charge of the complex is (−4−1)+1 = −4. - Since the complex is neutral, this must be balanced by the charge on the cobalt ion. - Therefore, cobalt must have a charge of +3, and its oxidation state is therefore +3. Next, we can use the known oxidation state of cobalt to determine its coordination number. The ligand NH₃ is a derivative of 1,10-phenanthroline, which is a bidentate ligand. This means that each ligand can bind to the metal at two points. - One NH₃ ligand binds to the metal via one nitrogen atom (N), and the other NH₃ ligand binds via two nitrogen atoms. This means that there are a total of three nitrogen atoms binding to the cobalt ion. - Since cobalt has an oxidation state of +3, it must have six ligands in total (since each ligand contributes one electron to the metal ion). - Therefore, there must be three additional ligands binding to the metal ion. These are the two sulfide ions and the chloride ion. - The total coordination number of the cobalt ion is therefore 6, and the answer is (C) 3 and 6.

The Oxidation and Coordination Numbers of Cobalt in the Compound