Which of the following is/are isoelectronic with `Na^(+)` ?

Options

A. `Ne`
B. `C_(2)`
C. `B_(2)`
D. `O_(2)^(2+)`

Explanation

To determine which species are isoelectronic with Na⁺, we first need to understand what isoelectronic means. Isoelectronic species are atoms or ions that have the same number of electrons.

### Step-by-Step Solution:

1. **Determine the Electron Count of Na⁺:**
- Sodium (Na) has an atomic number of 11, meaning it has 11 electrons.
- Na⁺ means that one electron has been removed from sodium, so:
\[ \text{Electrons in Na⁺} = 11 - 1 = 10 \]

2. **Identify the Candidates:**
- We need to check which of the given species have 10 electrons.

3. **Check Neon (Ne):**
- Neon is a noble gas with an atomic number of 10, meaning it has:
\[ \text{Electrons in Ne} = 10 \]
- Therefore, Ne is isoelectronic with Na⁺.

4. **Check C₂:**
- Each carbon atom has 6 electrons. Thus, for C₂:
\[ \text{Electrons in C₂} = 6 + 6 = 12 \]
- C₂ is not isoelectronic with Na⁺.

5. **Check B₂:**
- Each boron atom has 5 electrons. Thus, for B₂:
\[ \text{Electrons in B₂} = 5 + 5 = 10 \]
- B₂ is isoelectronic with Na⁺.

6. **Check O₂²⁺:**
- Each oxygen atom has 8 electrons. Thus, for O₂:
\[ \text{Electrons in O₂} = 8 + 8 = 16 \]
- Since O₂²⁺ means we remove 2 electrons:
\[ \text{Electrons in O₂²⁺} = 16 - 2 = 14 \]
- O₂²⁺ is not isoelectronic with Na⁺.

### Conclusion:
The species that are isoelectronic with Na⁺ are:
- Neon (Ne)
- B₂

### Final Answer:
- Neon (Ne) and B₂ are isoelectronic with Na⁺.