Which one of the following has minimum value of size of cation/anion ratio ?

Options

A. `NaCl`
B. `KCl`
C. `MgCl_2`
D. `CaF_2`

Explanation

To determine which compound has the minimum value of the size of the cation/anion ratio among NaCl, KCl, MgCl2, and CaF2, we can follow these steps:

### Step 1: Understand the Concept of Cation/Anion Ratio
The size of the cation/anion ratio is calculated by comparing the ionic radii of the cation (positively charged ion) and the anion (negatively charged ion). A smaller ratio indicates that the cation is smaller relative to the anion.

### Step 2: Identify the Ions in Each Compound
- **NaCl**: Na⁺ (sodium cation) and Cl⁻ (chloride anion)
- **KCl**: K⁺ (potassium cation) and Cl⁻ (chloride anion)
- **MgCl2**: Mg²⁺ (magnesium cation) and Cl⁻ (chloride anion)
- **CaF2**: Ca²⁺ (calcium cation) and F⁻ (fluoride anion)

### Step 3: Compare the Sizes of Cations
- **Na⁺**: Smaller than **K⁺** (since Na is above K in Group 1)
- **Mg²⁺**: Smaller than **Ca²⁺** (since Mg is above Ca in Group 2)

### Step 4: Compare the Sizes of Anions
- **Cl⁻**: Larger than **F⁻** (since Cl is below F in the periodic table)

### Step 5: Determine the Cation/Anion Ratio for Each Compound
- **NaCl**: Size ratio = size of Na⁺ / size of Cl⁻
- **KCl**: Size ratio = size of K⁺ / size of Cl⁻
- **MgCl2**: Size ratio = size of Mg²⁺ / size of Cl⁻
- **CaF2**: Size ratio = size of Ca²⁺ / size of F⁻

### Step 6: Analyze the Ratios
To find the minimum cation/anion ratio, we need:
- The smallest cation size and the largest anion size.

From our analysis:
- **Mg²⁺** is the smallest cation among the options.
- **Cl⁻** is the largest anion among the cations listed.

### Conclusion
The compound with the minimum cation/anion ratio is **MgCl2**.

### Final Answer
**MgCl2**

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