Question

What is the difference between the number of atoms per unit cell in face centred cube and the number of atoms per unit cell in body centred cube ?

• A. 1
• B. 2
• C. 4
• D. 6

Answer 1

The correct option is B 2

Number of atoms in face centred cubic unit cell, $X_F=8$ (cornered atoms)$\times \frac{1}{8}+6$ (face centred atom) $\times \frac{1}{2}=1+3=4$ atoms/unit cell

Number of atoms in body centred unit cell, $X_b$
=8 (cornered atoms) $\times \frac{1}{8}+1$ (body centred atom)
$=1+1=2$

$X_F-X_b=4-2=2$