Fe is converted to `Fe^(2+)`, the decreases in the number of electrons with magnetic quantum number zero are

Options

A. 0
B. 1
C. 2
D. 4

Answer

To solve the question regarding the decrease in the number of electrons with the magnetic quantum number \( m_l = 0 \) when iron (Fe) is converted to \( Fe^{2+} \), we can follow these steps:

### Step-by-Step Solution:

1. **Determine the Atomic Number of Iron (Fe)**:
- Iron has an atomic number of 26. This means it has 26 electrons in its neutral state.

2. **Write the Electronic Configuration of Neutral Iron (Fe)**:
- The electronic configuration of Fe is:
\[ 1s^2 \, 2s^2 \, 2p^6 \, 3s^2 \, 3p^6 \, 4s^2 \, 3d^6 \]

3. **Identify the Electronic Configuration of \( Fe^{2+} \)**:
- When iron loses two electrons to become \( Fe^{2+} \), the electrons are removed from the outermost shell first. The 4s electrons are removed before the 3d electrons.
- Therefore, the electronic configuration of \( Fe^{2+} \) will be:
\[ 1s^2 \, 2s^2 \, 2p^6 \, 3s^2 \, 3p^6 \, 3d^6 \]

4. **Identify the Electrons with Magnetic Quantum Number \( m_l = 0 \)**:
- The magnetic quantum number \( m_l \) describes the orientation of the orbital. For the s-orbitals (1s, 2s, 3s, 4s), \( m_l = 0 \).
- In the electronic configuration of \( Fe \), the 4s orbital has 2 electrons, both of which have \( m_l = 0 \).

5. **Determine the Change in the Number of Electrons with \( m_l = 0 \)**:
- Since the 4s orbital loses both of its electrons when transitioning from Fe to \( Fe^{2+} \), the number of electrons with \( m_l = 0 \) decreases from 2 to 0.
- Thus, the decrease in the number of electrons with \( m_l = 0 \) is:
\[ 2 - 0 = 2 \]

### Final Answer:
The decrease in the number of electrons with magnetic quantum number zero when Fe is converted to \( Fe^{2+} \) is **2**.

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