What is the coordination number of the central metal ion in $[\text{Co}({\text{NH}}_3{)}_6]{\text{Cl}}_3$?

Solution

1. The complex is $[\text{Co}({\text{NH}}_3{)}_6]{\text{Cl}}_3$.
2. There are 6 ammonia ligands attached to the cobalt ion.
3. Since ammonia is a monodentate ligand, the coordination number is $6\times 1=6$.
4. Hence the answer is (C).