The number of d-electrons retained in `Fe^(2+)` (At. no. of Fe = 26) ions is

Options

A. 3
B. 4
C. 5
D. 6

Explanation

To determine the number of d-electrons retained in the Fe²⁺ ion, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Atomic Number of Iron (Fe)**:
The atomic number of iron (Fe) is given as 26.

2. **Write the Ground State Electron Configuration of Iron**:
The electron configuration for a neutral iron atom (Fe) with atomic number 26 is:
\[ \text{Fe: } 1s^2 \, 2s^2 \, 2p^6 \, 3s^2 \, 3p^6 \, 4s^2 \, 3d^6 \]

3. **Determine the Charge of the Ion**:
We need to find the configuration for the Fe²⁺ ion, which means iron has lost 2 electrons.

4. **Remove Electrons to Form the Ion**:
Electrons are removed from the outermost shell first. In this case, the outermost shell is the 4s orbital. Therefore, we remove the two electrons from the 4s orbital:
\[ \text{Fe}^{2+}: 1s^2 \, 2s^2 \, 2p^6 \, 3s^2 \, 3p^6 \, 3d^6 \]

5. **Count the Remaining d-Electrons**:
After removing the 4s electrons, the remaining configuration shows that there are 6 electrons in the 3d orbital:
\[ \text{d-electrons in Fe}^{2+} = 6 \]

6. **Conclusion**:
The number of d-electrons retained in the Fe²⁺ ion is 6.

### Final Answer:
The number of d-electrons retained in Fe²⁺ is **6**.

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