Question

The number of atoms contained in a fcc unit cell of a monatomic substance is

• A. 1
• B. 2
• C. 3
• D. 4

Answer 1

The correct option is D 4

In face centred cubic unit cell (fcc) each particle is at the corner and at face centres.

Corner atoms contribute $\frac{1}{8}$ per unit cell and face centre atoms contribute $\frac{1}{2}$.

Now,

No. of atoms $=8\times \frac{1}{8}+6\times \frac{1}{2}=4$

Option D is correct.