In the cubic close 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 each of which is shared by four adjacent unit cells
D. 8 tetrahedral voids within the unit cells .

Explanation

To solve the question regarding the cubic close packing (CCP) and the properties of its unit cell, we can break it down into the following steps:

### Step-by-Step Solution:

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

2. **Determining the Number of Atoms per Unit Cell**:
- In a face-centered cubic (FCC) structure, there are a total of 4 atoms per unit cell. This is calculated as follows:
- 8 corner atoms contribute \( \frac{1}{8} \) of an atom each (since each corner atom is shared by 8 unit cells), totaling 1 atom.
- 6 face-centered atoms contribute \( \frac{1}{2} \) of an atom each (since each face atom is shared by 2 unit cells), totaling 3 atoms.
- Thus, the total number of atoms in the unit cell = \( 1 + 3 = 4 \).

3. **Calculating Tetrahedral Voids**:
- In a cubic close packing structure, the number of tetrahedral voids can be determined using the formula:
\[ \text{Number of tetrahedral voids} = 2 \times \text{Number of atoms in the unit cell} \]
- Since we have established that there are 4 atoms in the unit cell, we can calculate the number of tetrahedral voids:
\[ \text{Number of tetrahedral voids} = 2 \times 4 = 8 \]

4. **Conclusion**:
- Therefore, in the cubic close packing (CCP), the unit cell has **8 tetrahedral voids**.

### Final Answer:
In the cubic close packing, the unit cell has **8 tetrahedral voids**.