In Body centered cubic structures the atoms are not present at?

Options

A. Body centre
B. Corners
C. Centre of opposite faces
D. None of the above

Answer

To solve the question regarding the body-centered cubic (BCC) structure and where atoms are not present, we can follow these steps:

### Step 1: Understand the BCC Structure
In a body-centered cubic (BCC) structure, atoms are located at specific positions within the unit cell. The BCC unit cell has atoms at the corners and one atom at the center of the cube.

### Step 2: Identify Atom Positions
1. **Corner Atoms**: There are 8 corner atoms in a BCC unit cell. Each corner atom contributes 1/8 of an atom to the unit cell because it is shared among 8 adjacent unit cells.
2. **Body-Centered Atom**: There is 1 atom located at the center of the cube, which contributes fully (1 atom) to the unit cell.

### Step 3: Calculate the Total Number of Atoms
- Contribution from corner atoms: \(8 \times \frac{1}{8} = 1\)
- Contribution from the body-centered atom: \(1 \times 1 = 1\)

Thus, the total number of atoms (Z) in a BCC unit cell is:
\[ Z = 1 + 1 = 2 \]

### Step 4: Identify Where Atoms Are Not Present
The question asks where atoms are not present in the BCC structure. In a BCC unit cell:
- Atoms are present at the 8 corners and at the center of the cube.
- Atoms are **not present** at the center of the opposite faces of the cube.

### Conclusion
Therefore, the correct answer to the question is that atoms are not present at the center of the opposite face in a body-centered cubic structure.

### Final Answer
Atoms are not present at the center of the opposite face.

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