Specify the oxidation numbers of the metals in the following coordination entities:
(i). `[Co(H_2O)(CN)(en)_2]^(2+)`
(ii). `[CoBr_2(en)_2]^(o+)`
(iii). `[PtCl_4]^(2-)` (iv). `K_3[Fe(CN)_6]`
(v). `[Cr(NH_3)_3Cl_3]`

Explanation

To determine the oxidation numbers of the metals in the given coordination entities, we can follow these steps:

### Step-by-Step Solution:

#### (i) For `[Co(H_2O)(CN)(en)_2]^(2+)`:

1. **Identify the ligands**:
- H2O (water) is a neutral ligand, oxidation number = 0.
...