Question

What is the percentage of free space in body centered cubic unit cell?

• A. 0.32
• B. 0.2
• C. 0.34
• D. 0.28

Answer 1

Answer: (A)

0.32

Answer 2

For bcc unit cell,
Packing fraction $=\frac{\text { Total volume of spheres }}{\text { Volume of the unit cell }}$
$=\frac{\frac{8}{3} \pi r^{3}}{\frac{64}{3 \sqrt{3}} r^{3}}=0.68$.
$\therefore \%$ of occupied space
$=0.68 \times 100$
$=68$
$\therefore \%$ of free space $=100-68=32$