Final answer:
The oxidation state of cobalt in [Co(NH3)6]Cl3 is +3, the number of d electrons is 6, and all d electrons are paired resulting in zero unpaired electrons; hence, none of the provided options are correct.
Step-by-step explanation:
The student is asking about the oxidation state of the metal, the number of d electrons, and the number of unpaired electrons for the coordination compound [Co(NH3)6]Cl3.
To find these properties, we look at the complex ion [Co(NH3)6]3+ and use the knowledge that ammonia (NH3) is a neutral ligand and chloride ions have a charge of -1. The overall charge of the complex ion is +3, which means cobalt must have an oxidation state of +3 to balance the charge of the six neutral NH3 ligands.
Cobalt in its elemental form has an electron configuration that ends in 3d7 4s2. When cobalt loses three electrons to become Co3+, it loses the two 4s electrons and one 3d electron, leaving it with six d electrons (3d6). In this configuration, cobalt has no unpaired electrons as the d orbitals are fully paired in a low spin configuration due to the strong field produced by the NH3 ligands.
Therefore, the correct answer is that the oxidation state of cobalt in the complex [Co(NH3)6]Cl3 is +3, the number of d electrons is 6, and the number of unpaired electrons is 0. So none of the options provided (a, b, c, d) are correct.