In the cubic close packing, the unit cell has

Options

A. 4 tetrahedral voids each of which is shared by four adjacent unit cells
B. 4 tetrahedral voids within the unit cell
C. 8 tetrahedral voids cach of which is shared by four adjacent unit cells
D. 8 tetrahedral voids within the unit cells

Explanation

To solve the question regarding the number of tetrahedral voids in a cubic close packing unit cell, we will follow these steps:

### Step-by-Step Solution:

1. **Understanding Cubic Close Packing (CCP)**:
- Cubic close packing is also referred to as face-centered cubic (FCC) structure. In this arrangement, atoms are densely packed in a three-dimensional structure.

2. **Identifying Tetrahedral Voids**:
- Tetrahedral voids are the empty spaces in the crystal lattice where smaller atoms can fit. In a cubic close packing, tetrahedral voids are located along the body diagonals of the unit cell.

3. **Locating Tetrahedral Voids**:
- Each body diagonal of the cube contains 2 tetrahedral voids. The body diagonal runs from one corner of the cube to the opposite corner.

4. **Counting Body Diagonals**:
- A cube has 4 body diagonals. Therefore, the total number of tetrahedral voids can be calculated by multiplying the number of body diagonals by the number of tetrahedral voids per diagonal.

5. **Calculation**:
- Total Tetrahedral Voids = Number of Body Diagonals × Tetrahedral Voids per Diagonal
- Total Tetrahedral Voids = 4 (body diagonals) × 2 (voids per diagonal) = 8 tetrahedral voids.

6. **Conclusion**:
- Therefore, in a cubic close packing unit cell, there are a total of 8 tetrahedral voids within the unit cell.

### Final Answer:
The unit cell in cubic close packing has **8 tetrahedral voids within the unit cell**.

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