Which of the following has largest radius?

Options

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

Answer

To determine which of the given species has the largest radius, we will analyze the relationship between ionic charge and atomic size. Here’s a step-by-step solution:

### Step 1: Identify the Species
Let's assume we are comparing the following ions:
- N³⁻ (Nitride ion)
- Na⁺ (Sodium ion)
- F⁻ (Fluoride ion)
- Al³⁺ (Aluminum ion)

### Step 2: Understand Ionic Charges
- N³⁻ has gained 3 electrons, resulting in a negative charge.
- Na⁺ has lost 1 electron, resulting in a positive charge.
- F⁻ has gained 1 electron, resulting in a negative charge.
- Al³⁺ has lost 3 electrons, resulting in a positive charge.

### Step 3: Compare Cations and Anions
- Cations (like Na⁺ and Al³⁺) are smaller than their parent atoms because they lose electrons and thus have a higher effective nuclear charge acting on the remaining electrons.
- Anions (like N³⁻ and F⁻) are larger than their parent atoms because they gain electrons, which increases electron-electron repulsion and decreases effective nuclear charge per electron.

### Step 4: Analyze the Size Based on Charge
- Among the cations, Na⁺ is larger than Al³⁺ because it has lost fewer electrons.
- Among the anions, N³⁻ is larger than F⁻ because it has gained more electrons (3 electrons vs. 1 electron).

### Step 5: Conclusion
Since anions are generally larger than cations and N³⁻ has a greater negative charge than F⁻, we conclude that N³⁻ will have the largest radius among the given species.

### Final Answer
**N³⁻ has the largest radius.**

---