Of the following the ion with the largest size is

Options

A. `Na^+ `
B. `N^(3– )`
C. `F^– `
D. `Al^(3+)`

Answer

To determine which ion has the largest size among the given options, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Ions and Their Atomic Numbers:**
- Sodium (Na): Atomic number = 11
- Nitrogen (N): Atomic number = 7
- Fluorine (F): Atomic number = 9
- Aluminium (Al): Atomic number = 13

2. **Determine the Number of Protons and Electrons in Each Ion:**
- Sodium ion (Na⁺): Loses 1 electron → Protons = 11, Electrons = 10
- Nitrogen ion (N³⁻): Gains 3 electrons → Protons = 7, Electrons = 10
- Fluorine ion (F⁻): Gains 1 electron → Protons = 9, Electrons = 10
- Aluminium ion (Al³⁺): Loses 3 electrons → Protons = 13, Electrons = 10

3. **Calculate the Proton-to-Electron Ratio:**
- Sodium (Na⁺): 11 protons / 10 electrons = 1.1
- Nitrogen (N³⁻): 7 protons / 10 electrons = 0.7
- Fluorine (F⁻): 9 protons / 10 electrons = 0.9
- Aluminium (Al³⁺): 13 protons / 10 electrons = 1.3

4. **Analyze the Effective Nuclear Charge:**
- The effective nuclear charge (Z_eff) is higher when there are more protons attracting the same number of electrons. This leads to a smaller ionic size.
- Since all ions have 10 electrons, the one with the least number of protons will have the largest size due to the lower effective nuclear charge.

5. **Determine the Ion with the Largest Size:**
- Among the ions, Nitrogen (N³⁻) has the least number of protons (7) attracting 10 electrons, which means it will have the largest ionic size.

### Conclusion:
The ion with the largest size is **Nitrogen ion (N³⁻)**.