Question

In an atomic bcc, what fraction of edge is not covered by atoms?

• A. 0.32
• B. 0.16
• C. 0.134
• D. 0.268

Answer 1

The correct option is C 0.134

Edge not covered by atom = a - 2r
In bcc, $4r=\sqrt{3}a$
Edge not covered = $a-\frac{\sqrt{3}a}{2}=a\left[\frac{2-\sqrt{3}}{2}\right]$
$\Rightarrow$ fraction of edge not covered by atoms= $\frac{2-\sqrt{3}}{2}=0.134$