Which of the following pairs will form the most stable ionic bond ?

Options

A. Na and Cl
B. Mg and F
C. Li and F
D. Na and F

Explanation

To determine which pair will form the most stable ionic bond, we need to analyze the options based on the charges of the ions involved and the concept of lattice energy.

### Step-by-Step Solution:

1. **Understanding Ionic Bonds**: Ionic bonds are formed between positively charged ions (cations) and negatively charged ions (anions). The stability of these bonds is influenced by the lattice energy, which is the energy released when ions form a solid lattice from gaseous ions.

2. **Identifying the Options**: The given pairs are:
- A) Na and Cl
- B) Mg and F
- C) Li and F
- D) Na and F

3. **Determining Charges**:
- For Na and Cl: Na⁺ (charge +1) and Cl⁻ (charge -1)
- For Mg and F: Mg²⁺ (charge +2) and F⁻ (charge -1)
- For Li and F: Li⁺ (charge +1) and F⁻ (charge -1)
- For Na and F: Na⁺ (charge +1) and F⁻ (charge -1)

4. **Analyzing Lattice Energy**: Lattice energy is affected by the charges of the ions:
- Higher charges lead to greater lattice energy, which means a more stable ionic bond.
- Mg²⁺ has a higher charge (+2) compared to Na⁺ and Li⁺ (+1).

5. **Comparing Lattice Energies**:
- Na and Cl: Lattice energy is moderate due to +1 and -1 charges.
- Mg and F: Lattice energy is high due to +2 and -1 charges.
- Li and F: Lattice energy is moderate due to +1 and -1 charges.
- Na and F: Lattice energy is moderate due to +1 and -1 charges.

6. **Conclusion**: Since Mg²⁺ has the highest charge among the cations, the pair Mg and F will form the most stable ionic bond due to the significantly higher lattice energy.

### Final Answer:
The pair that will form the most stable ionic bond is **B) Mg and F**.