Unit Cells

Step 1: Understanding the Concept:
CsCl has a body-centred cubic (BCC) type structure.

Step 2: Detailed Explanation:
In CsCl, each Cs ion is surrounded by 8 Cl ions (at the corners of a cube), and each Cl ion is surrounded by 8 Cs ions (at the body centre positions of adjacent cubes). So coordination number is 8:8.

Step 3: Final Answer:
8, 8