Question

Choose the correct statement(s) regarding unit cell.

• A. Particle at the face-centre is shared by 8 unit cells.
• B. Particle at the corner of a unit cell is shared by eight-unit cells
• C. Particle at the corner of a unit cell is shared by four unit cells
• D. Particle at face centre contributes $\frac{1}{2}$ part to one unit cell.

Answer 1

Answer: (B), (D)

Particle at face centre contributes $\frac{1}{2}$ part to one unit cell.

Contribution of corner particles:
A particle at the corner of a unit cell is shared by eight-unit cells. So, each particle contributes $\frac{1}{8}$ part to the unit cell.

Contribution of face-centred particle:
A particle at the face-centre is shared by two-unit cells.
So, each particle contributes $\frac{1}{2}$ part to the unit cell.
Thus, statements (b) and (d) are correct.