Question

Lithium mettal crystallises in a body centred cubic crystal.If the length of the side of the unit cell of lithium is 351pm, the atomic radius of the lithium will be:

• A. 151.8pm
• B. 75.7pm
• C. 300.5pm
• D. 240.8pm

Answer 1

Answer: (A)

151.8pm

Edge length $=351$ pm
For BCC structure,
$a\sqrt{3}=4r$
$r=a\frac{\sqrt{3}}{4}$
$r=351\times \frac{1.7321}{4}$
$r=151.8pm$