The mass of a unit cell of CsCl corresponds to the combined masses of :

Options

A. ` 8 Cs^(+)` and `1 Cl^(–)` ions
B. `1 Cs^(+)` and `6 Cl^(–)` ions
C. `1 Cs^(+)` and `1 Cl^(–)` ions
D. `4 Cs^(+)` and `1 Cl^(–)` ions

Answer

To determine the mass of a unit cell of CsCl (cesium chloride) and what it corresponds to, we need to analyze the structure of CsCl and the arrangement of its ions in the unit cell.

### Step-by-Step Solution:

1. **Understanding the Structure of CsCl**:
- CsCl crystallizes in a body-centered cubic (BCC) structure. In this structure, ions are arranged in a specific manner.

2. **Identifying the Ions in the Unit Cell**:
- In the BCC structure of CsCl, there are:
- 1 cesium ion (Cs⁺) located at the center of the cube.
- 8 chloride ions (Cl⁻) located at the corners of the cube.

3. **Counting the Contribution of Corner Ions**:
- Each corner of the cube contributes 1/8 of an ion to the unit cell because each corner is shared by 8 adjacent unit cells.
- Since there are 8 corners, the total contribution from the chloride ions is:
\[ 8 \text{ corners} \times \frac{1}{8} = 1 \text{ Cl}^- \]

4. **Total Ions in the Unit Cell**:
- Therefore, in total, the unit cell of CsCl contains:
- 1 Cs⁺ ion (from the center)
- 1 Cl⁻ ion (from the corners)

5. **Conclusion**:
- The mass of a unit cell of CsCl corresponds to the combined masses of 1 cesium ion and 1 chloride ion.

### Answer:
The mass of a unit cell of CsCl corresponds to the combined masses of **1 Cs⁺ ion and 1 Cl⁻ ion**.