Assertion : Coordination number of Fe and Co in `[Fe(C_(2) O_(4))_(3)]^(3-)` and `[Co(en)_(3)]^(3+)` respectively is 6 .
Reason : `C_(2)O_(4)^(2-)` and en (ethane-1 , 2 - diamine) are didentate ligands.

Options

A. If both Assertion and reason are true and reason is the correct explanation of assertion
B. If both assertion and reason are true but reason is not the correct explanation of assertion
C. If assertion is true but reason is false
D. if both assertion and reason are false

Answer

To solve the question, we need to analyze the assertion and reason provided regarding the coordination numbers of the complexes `[Fe(C₂O₄)₃]³⁻` and `[Co(en)₃]³⁺`.

### Step-by-Step Solution:

1. **Understanding Coordination Number:**
The coordination number of a metal in a coordination complex is defined as the total number of coordinate bonds formed between the central metal atom and the ligands surrounding it.

2. **Identifying the Ligands:**
- In the complex `[Fe(C₂O₄)₃]³⁻`, the ligand is oxalate, represented as `C₂O₄²⁻`.
- In the complex `[Co(en)₃]³⁺`, the ligand is ethylenediamine (en), which is represented as `NH₂CH₂CH₂NH₂`.

3. **Analyzing the Ligands:**
- **Oxalate (C₂O₄²⁻)**: This is a bidentate ligand, meaning it can form two coordinate bonds with the central metal atom (Fe in this case). Since there are three oxalate ligands in the complex, the total number of coordinate bonds contributed by the ligands is:
\[ 3 \text{ (oxalate ligands)} \times 2 \text{ (bonds per oxalate)} = 6 \text{ coordinate bonds} \]
- **Ethylenediamine (en)**: This is also a bidentate ligand. Each ethylenediamine ligand can form two coordinate bonds with the central metal atom (Co in this case). Since there are three ethylenediamine ligands in the complex, the total number of coordinate bonds contributed by the ligands is:
\[ 3 \text{ (ethylenediamine ligands)} \times 2 \text{ (bonds per ethylenediamine)} = 6 \text{ coordinate bonds} \]

4. **Conclusion on Coordination Numbers:**
- For the complex `[Fe(C₂O₄)₃]³⁻`, the coordination number of Fe is 6.
- For the complex `[Co(en)₃]³⁺`, the coordination number of Co is also 6.

5. **Evaluating the Assertion and Reason:**
- **Assertion**: The coordination number of Fe and Co in `[Fe(C₂O₄)₃]³⁻` and `[Co(en)₃]³⁺` respectively is 6. This is **True**.
- **Reason**: `C₂O₄²⁻` and en (ethylenediamine) are bidentate ligands. This is also **True**.

Since both the assertion and reason are true, and the reason correctly explains the assertion, we conclude that the answer is correct.

### Final Answer:
Both the assertion and reason are true, and the reason correctly explains the assertion.

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