Which of the following configuration of ions has zero CFSE in both strong and weak ligand fields ?

Options

A. `d^(10)`
B. `d^(8)`
C. `d^(6)`
D. `d^(4)`

Answer

To determine which configuration of ions has zero Crystal Field Stabilization Energy (CFSE) in both strong and weak ligand fields, we need to analyze the electron configurations of the given d-orbitals.

### Step-by-Step Solution:

1. **Understanding CFSE**:
- CFSE is the energy difference between the stabilized state of the d-electrons in a crystal field and the energy of the free d-electrons. It is influenced by the arrangement of d-electrons in the presence of ligands.

2. **Identify Electron Configurations**:
- The common d-electron configurations to consider are d4, d6, d8, and d10.

3. **Calculate CFSE for d10 Configuration**:
- For d10, all d-orbitals are fully filled. In both strong and weak fields, there is no splitting of d-orbitals because all orbitals are filled.
- CFSE = 0 (since there are no unpaired electrons and no energy difference).

4. **Calculate CFSE for d8 Configuration**:
- In a strong field, the filling will lead to pairing of electrons, resulting in a negative CFSE.
- In a weak field, the electrons will fill singly first, leading to a different CFSE calculation, which will also not be zero.

5. **Calculate CFSE for d6 Configuration**:
- In a strong field, the electrons will pair, leading to a negative CFSE.
- In a weak field, the electrons will fill singly first, but the CFSE will still not be zero.

6. **Calculate CFSE for d4 Configuration**:
- In a strong field, the electrons will pair, leading to a negative CFSE.
- In a weak field, the electrons will fill singly, but again the CFSE will not be zero.

7. **Conclusion**:
- The only configuration that results in zero CFSE in both strong and weak ligand fields is **d10**.

### Final Answer:
The configuration of ions that has zero CFSE in both strong and weak ligand fields is **d10**.

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