Which of the following pairs can form a compound with the maximum ionic character ?

Options

A. Na and Cl
B. Cs and F
C. Cs and I
D. Na and F

Explanation

To determine which pair can form a compound with the maximum ionic character, we need to analyze the properties of the ions involved, specifically their sizes. Ionic character is influenced by the size of the cations and anions: larger cations and smaller anions generally lead to a higher ionic character.

### Step-by-Step Solution:

1. **Identify the Ions**:
- We are given three anions: Cl⁻ (chloride), F⁻ (fluoride), and I⁻ (iodide).
- We need to consider cations that can pair with these anions. For this example, let's consider cesium (Cs⁺) as a potential cation.

2. **Analyze the Sizes of the Ions**:
- **Cations**: Cesium (Cs⁺) is a large cation as it is from the 6th period of the periodic table.
- **Anions**: Among the anions, fluoride (F⁻) is the smallest, followed by chloride (Cl⁻), and iodide (I⁻) is the largest.

3. **Determine the Ionic Character**:
- The ionic character of a compound is maximized when the cation is large and the anion is small.
- In this case, Cs⁺ (large cation) and F⁻ (small anion) would form a compound with maximum ionic character.

4. **Conclusion**:
- Therefore, the pair that can form a compound with the maximum ionic character is **Cesium Fluoride (CsF)**.

### Final Answer:
The pair that can form a compound with the maximum ionic character is **Cesium Fluoride (CsF)**.

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