The number of d-electrons in ` Fe^(2+) (Z= 26 ) ` is not equal to that of :

Options

A. p-electrons in `Ne (Z=10)`
B. p-electrons in `Me (Z=12)`
C. p-electrons in `Fe (Z=26)`
D. p-electrons in `Cl (Z=17)`

Explanation

To find the number of d-electrons in \( \text{Fe}^{2+} \) (Z = 26) and compare it with other elements, we can follow these steps:

### Step 1: Determine the electron configuration of neutral Iron (Fe)
- The atomic number of Iron (Fe) is 26, which means it has 26 electrons.
- The electron configuration for neutral Iron is:
\[ \text{Fe: } 1s^2 \, 2s^2 \, 2p^6 \, 3s^2 \, 3p^6 \, 4s^2 \, 3d^6 \]
- This can be simplified to:
\[ \text{Fe: } [\text{Ar}] \, 4s^2 \, 3d^6 \]

### Step 2: Determine the electron configuration of \( \text{Fe}^{2+} \)
- When Iron loses 2 electrons to form \( \text{Fe}^{2+} \), the electrons are removed first from the 4s subshell before the 3d subshell.
- Therefore, the electron configuration for \( \text{Fe}^{2+} \) is:
\[ \text{Fe}^{2+}: [\text{Ar}] \, 3d^6 \]

### Step 3: Count the number of d-electrons in \( \text{Fe}^{2+} \)
- From the configuration \( 3d^6 \), we see that there are 6 d-electrons in \( \text{Fe}^{2+} \).

### Step 4: Compare the number of d-electrons with other elements
- We need to compare the number of d-electrons in \( \text{Fe}^{2+} \) with the d-electrons in other elements.
- Let's consider the following elements:
- Neon (Ne): \( 1s^2 \, 2s^2 \, 2p^6 \) → No d-electrons (0)
- Magnesium (Mg): \( 1s^2 \, 2s^2 \, 2p^6 \, 3s^2 \) → No d-electrons (0)
- Chlorine (Cl): \( 1s^2 \, 2s^2 \, 2p^6 \, 3s^2 \, 3p^5 \) → No d-electrons (0)
- Scandium (Sc): \( [\text{Ar}] \, 4s^2 \, 3d^1 \) → 1 d-electron
- Titanium (Ti): \( [\text{Ar}] \, 4s^2 \, 3d^2 \) → 2 d-electrons
- Vanadium (V): \( [\text{Ar}] \, 4s^2 \, 3d^3 \) → 3 d-electrons
- Chromium (Cr): \( [\text{Ar}] \, 4s^2 \, 3d^5 \) → 5 d-electrons
- Manganese (Mn): \( [\text{Ar}] \, 4s^2 \, 3d^5 \) → 5 d-electrons

### Conclusion
- The number of d-electrons in \( \text{Fe}^{2+} \) is 6, which is not equal to that of Neon, Magnesium, Chlorine, Scandium, Titanium, Vanadium, Chromium, and Manganese.

### Final Answer
The number of d-electrons in \( \text{Fe}^{2+} \) is not equal to that of Neon, Magnesium, or Chlorine.