Question

If face centred atom contributes one third atom per unit cell then calculate the total number of atoms in FCC unit cell.
(correct answer +2, wrong answer -0.5)

• A. $4$
• B. $3$
• C. $6$
• D. $1$

Answer 1

The correct option is B $3$

$8$ corner atoms $\times$ contribution of 1 corner atom in unit cell -
$8$ $\times$ $\frac{1}{8}=1$
$6$ face centred atoms $\times$ contribution of 1 face centred atom in unit cell -
$6$ $\times$ $\frac{1}{3}=2$
Total number of atoms $=1+2=3$