Among the following which has the highest cation to anion size ratio ?

Options

A. CsF
B. LiF
C. NaF
D. CsI

Answer

To determine which compound has the highest cation to anion size ratio among the given options, we need to analyze the sizes of the cations and anions involved.

**Step 1: Identify the Cations and Anions**
- The cations provided are: Cs⁺, Na⁺, and Li⁺.
- The anions provided are: I⁻ and F⁻.

**Step 2: Determine the Size Order of Cations**
- The sizes of the cations can be ranked as follows:
- Cs⁺ > Na⁺ > Li⁺
- This indicates that Cs⁺ is the largest cation, while Li⁺ is the smallest.

**Step 3: Determine the Size Order of Anions**
- The sizes of the anions can be ranked as follows:
- I⁻ > F⁻
- This indicates that I⁻ is the largest anion, while F⁻ is the smallest.

**Step 4: Analyze the Cation to Anion Size Ratio**
- To maximize the cation to anion size ratio, we need a large cation and a small anion.
- From our previous analysis:
- The largest cation is Cs⁺.
- The smallest anion is F⁻.

**Step 5: Identify the Compound with the Highest Ratio**
- The compound that contains the largest cation (Cs⁺) and the smallest anion (F⁻) is CsF.
- Therefore, CsF has the highest cation to anion size ratio.

**Final Answer: CsF has the highest cation to anion size ratio.**

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