Q. A fcc unit cell of aluminium contains the equivalent of how may atoms?
A) 1
B) 2
C) 3
D) 4
Explanation
(d)
In fcc atoms are present at faces and corners.
Number of atoms in fcc = atoms at corners
+ atoms at faces of unit cell.
= (no. of corners $\times$ contribution by one atom)
+ (no. of faces $\times$ contribution by one atom)
$= \left( 8 \times \frac{1}{8} \right) + \left( 6 \times \frac{1}{2} \right) = 1 + 3 = 4$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.