Which of the following pairs are isoelectronic ?
Na, Mg

Explanation

To determine which pairs are isoelectronic, we need to understand what isoelectronic means. Isoelectronic species are those that have the same number of electrons. Here’s how to analyze the given pairs:

### Step-by-Step Solution:

1. **Identify the Atomic Numbers**:
- Sodium (Na) has an atomic number of 11.
- Magnesium (Mg) has an atomic number of 12.

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