If `'Z'` is the number of atoms in the unit cell that represents the closet packing sequence……`ABCABC`….. The number of octahedral voids in the unit cell is equal

Options

A. Z
B. 2Z
C. `Z//2`
D. `Z//4`

Answer

To solve the question regarding the number of octahedral voids in a unit cell that represents the closest packing sequence (ABCABC), we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Closest Packing**:
- In closest packing arrangements such as Hexagonal Close Packing (HCP) and Cubic Close Packing (CCP), the arrangement of atoms follows a repeating sequence of layers, typically denoted as ABCABC.

2. **Identifying the Number of Atoms (Z)**:
- Let 'Z' represent the number of atoms in the unit cell. In the context of closest packing, Z corresponds to the number of atoms that fit within the unit cell.

3. **Determining Octahedral Voids**:
- In both HCP and CCP arrangements, the number of octahedral voids present in the unit cell is equal to the number of atoms in the unit cell. This is a characteristic feature of these packing structures.

4. **Conclusion**:
- Since the number of octahedral voids is equal to the number of atoms (Z) in the unit cell, we conclude that the number of octahedral voids is Z.

### Final Answer:
- The number of octahedral voids in the unit cell is equal to **Z**.