Which of the following is iso-electronic with neon-

Options

A. `O^(2-)`
B. `F^(+)`
C. `Mg`
D. `Na`

Explanation

To determine which species is iso-electronic with neon, we need to find a species that has the same number of electrons as neon.

### Step-by-Step Solution:

1. **Identify the number of electrons in Neon:**
- Neon (Ne) has an atomic number of 10, which means it has 10 electrons.

2. **Understand the concept of isoelectronic species:**
- Isoelectronic species are atoms or ions that have the same number of electrons.

3. **Evaluate the given options:**
- We need to analyze the number of electrons in each species provided in the options.

4. **Check the first option: O²⁻ (oxide ion):**
- Oxygen (O) has an atomic number of 8, meaning it has 8 electrons in its neutral state.
- The O²⁻ ion has gained 2 additional electrons, resulting in:
\[ 8 + 2 = 10 \text{ electrons} \]
- Therefore, O²⁻ is isoelectronic with Ne.

5. **Check the second option: F⁺ (fluorine ion):**
- Fluorine (F) has an atomic number of 9, meaning it has 9 electrons in its neutral state.
- The F⁺ ion has lost 1 electron, resulting in:
\[ 9 - 1 = 8 \text{ electrons} \]
- Therefore, F⁺ is not isoelectronic with Ne.

6. **Check the third option: Mg (magnesium):**
- Magnesium (Mg) has an atomic number of 12, meaning it has 12 electrons in its neutral state.
- Therefore, Mg is not isoelectronic with Ne.

7. **Check the fourth option: Na (sodium):**
- Sodium (Na) has an atomic number of 11, meaning it has 11 electrons in its neutral state.
- Therefore, Na is not isoelectronic with Ne.

8. **Conclusion:**
- The only species that is isoelectronic with neon is O²⁻.

### Final Answer:
- The species that is iso-electronic with neon is **O²⁻**.