Question

The number of atoms contained in an fcc unit cell of a monoatomic substance is:

• A. 1
• B. 2
• C. 4
• D. 6

Answer 1

Answer: (C)

4

FCC unit cell contains 8 corner atoms and 6 face atoms.

Contribution of corner atom toward cell is 1/8.

Contribution of face atom toward cell is 1/2.

Due to corner atoms, no of atoms in FCC unit cell is $8\times 1/8=1atom$

Due to face atoms, no of atoms in FCC unit cell is $6\times 1/2=3atoms$

Total no. of atoms are $3+1=4atoms$