Which response given the correct coordination number (C.N) and oxidation number (O.N) of the transition metal atom in `[Co (NH_3)_2(H_2O)_2Cl_2]^+` ?

Options

A. `C.N. = 3,O.N = +1`
B. `C.N. = 4,O.N = +2`
C. `C.N. = 6,O.N = +1`
D. `C.N. = 6,O.N = +3`

Answer

To determine the coordination number (C.N) and oxidation number (O.N) of the transition metal atom in the complex \([Co(NH_3)_2(H_2O)_2Cl_2]^+\), we can follow these steps:

### Step 1: Identify the Ligands
The complex contains:
- 2 Ammonia (NH₃) ligands
- 2 Water (H₂O) ligands
- 2 Chloride (Cl⁻) ligands

### Step 2: Count the Coordination Number
The coordination number is determined by the number of ligands attached to the central metal atom (cobalt in this case).
- Each NH₃ is a monodentate ligand (binds through one site).
- Each H₂O is also a monodentate ligand.
- Each Cl⁻ is a monodentate ligand.

Adding these together:
- NH₃: 2 ligands
- H₂O: 2 ligands
- Cl⁻: 2 ligands

Total coordination number (C.N) = 2 (NH₃) + 2 (H₂O) + 2 (Cl⁻) = 6.

### Step 3: Determine the Oxidation Number
To find the oxidation number of cobalt (Co), we can set up an equation based on the overall charge of the complex.

Let the oxidation number of cobalt be \(x\).

The charges of the ligands are as follows:
- NH₃: 0 (neutral)
- H₂O: 0 (neutral)
- Cl⁻: -1 (each chloride contributes -1, and there are 2 Cl⁻)

The overall charge of the complex is +1. Therefore, we can write the equation:
\[ x + 0 + 0 - 2 = +1 \]
Solving for \(x\):
\[ x - 2 = 1 \\ x = 1 + 2 \\ x = +3 \]

### Conclusion
The coordination number (C.N) of cobalt in the complex is 6, and the oxidation number (O.N) is +3.

### Final Answer
- Coordination Number (C.N): 6
- Oxidation Number (O.N): +3