In case of FCC(Face centered cubic) structure the atoms are not present at?

Options

A. body centre
B. Corners
C. faces
D. None of the above

Answer

To solve the question regarding the FCC (Face Centered Cubic) structure and where the atoms are not present, we can follow these steps:

### Step 1: Understand the FCC Structure
In a Face Centered Cubic (FCC) structure, atoms are located at specific positions within the unit cell. The key positions are:
- At the corners of the cube
- At the centers of each face of the cube

### Step 2: Identify Atom Positions
1. **Corner Atoms**: There are 8 corner atoms in an FCC unit cell. Each corner atom contributes \( \frac{1}{8} \) of an atom to the unit cell because it is shared among 8 neighboring unit cells.
2. **Face-Centered Atoms**: There are 6 face-centered atoms. Each face-centered atom contributes \( \frac{1}{2} \) of an atom to the unit cell because it is shared between 2 unit cells.

### Step 3: Calculate the Effective Number of Atoms (Z)
To find the total number of effective atoms (Z) in the FCC structure:
- From corners: \( 8 \text{ corners} \times \frac{1}{8} = 1 \text{ atom} \)
- From faces: \( 6 \text{ faces} \times \frac{1}{2} = 3 \text{ atoms} \)

Adding these together gives:
\[ Z = 1 + 3 = 4 \]

### Step 4: Determine Where Atoms Are Not Present
In the FCC structure, atoms are present at:
- Corners
- Face centers

However, atoms are **not** present at:
- The body center of the cube.

### Conclusion
Thus, in the FCC structure, the atoms are not present at the body center.

### Final Answer
The atoms are not present at the body center in the FCC structure.

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