In the crystal structure of `CsCl:`

Options

A. Body centred cubic
B. Simple cubic
C. Face centred cubic
D. Edge centred cubic

Explanation

To solve the question regarding the crystal structure of CsCl (cesium chloride), we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Crystal Structure**:
- CsCl is a type of ionic compound. To determine its crystal structure, we need to analyze how the ions are arranged in the lattice.

2. **Drawing the Structure**:
- In the CsCl crystal structure, the cesium ions (Cs⁺) and chloride ions (Cl⁻) are arranged in a specific manner.
- The chloride ions are located at the corners of a cube, while the cesium ion is positioned at the center of the cube.

3. **Coordination Number**:
- The coordination number refers to the number of nearest neighboring ions surrounding a particular ion in the lattice.
- In the case of CsCl, each Cs⁺ ion is surrounded by 8 Cl⁻ ions, and each Cl⁻ ion is surrounded by 8 Cs⁺ ions. This indicates a coordination number of 8 for both ions.

4. **Identifying the Type of Lattice**:
- The arrangement of ions in CsCl corresponds to a body-centered cubic (BCC) structure. In a BCC structure, there is one atom at each corner of the cube and one atom at the center of the cube.

5. **Conclusion**:
- Based on the arrangement and coordination number, we conclude that the crystal structure of CsCl is body-centered cubic (BCC).

### Final Answer:
The crystal structure of CsCl is **Body-centered cubic (BCC)**.