The isoelectronic set of ions is:

Options

A. `N^(3-) , O^(2-), F^(-) " and " Na^(+)`
B. `Li^(+) , Na^(+) , O^(2-) " and " F^(-)`
C. `N^(3-) , Li^(+) , Mg^(2+) " and " O^(2-)`
D. `F^(-), Li^(+) , Na^(+) " and " Mg^(2+)`

Explanation

To determine the isoelectronic set of ions, we need to identify ions that have the same number of electrons, even if they come from different elements. Here’s a step-by-step solution:

### Step 1: Understand Isoelectronic Species
Isoelectronic species are ions or atoms that have the same number of electrons but different nuclear charges.

### Step 2: Analyze Each Option
We will analyze the given options to check which set of ions has the same number of electrons.

#### Option 1: N³⁻, O²⁻, F⁻, Na⁺
- **N³⁻**: Nitrogen (N) has 7 electrons. With a charge of -3, it gains 3 electrons, resulting in 10 electrons.
- **O²⁻**: Oxygen (O) has 8 electrons. With a charge of -2, it gains 2 electrons, resulting in 10 electrons.
- **F⁻**: Fluorine (F) has 9 electrons. With a charge of -1, it gains 1 electron, resulting in 10 electrons.
- **Na⁺**: Sodium (Na) has 11 electrons. With a charge of +1, it loses 1 electron, resulting in 10 electrons.

All four ions have 10 electrons. Therefore, this option is isoelectronic.

#### Option 2: Li²⁺, Na⁺
- **Li²⁺**: Lithium (Li) has 3 electrons. With a charge of +2, it loses 2 electrons, resulting in 1 electron.
- **Na⁺**: Sodium (Na) has 11 electrons. With a charge of +1, it loses 1 electron, resulting in 10 electrons.

These ions do not have the same number of electrons.

#### Option 3: N³⁻, Li⁺
- **N³⁻**: As calculated, it has 10 electrons.
- **Li⁺**: Lithium (Li) has 3 electrons. With a charge of +1, it loses 1 electron, resulting in 2 electrons.

These ions do not have the same number of electrons.

#### Option 4: F⁻, Li⁺
- **F⁻**: As calculated, it has 10 electrons.
- **Li⁺**: As calculated, it has 2 electrons.

These ions do not have the same number of electrons.

### Step 3: Conclusion
The only set of ions that is isoelectronic is from Option 1: N³⁻, O²⁻, F⁻, and Na⁺.

### Final Answer
The isoelectronic set of ions is: **N³⁻, O²⁻, F⁻, Na⁺**.

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