Question

Lithium metal crystallises in a body-centred cubic crystal. If the length of the side of the unit cell of lithium is $351\text{pm}$, the atomic radius of lithium will be:

• A. $151.8\text{pm}$
• B. $300.5\text{pm}$
• C. $75.5\text{pm}$
• D. $240.8\text{pm}$

Answer 1

The correct option is A $151.8\text{pm}$

Since, $Li$ crystallises in body centered cubic crystal, atomic radius,
$r=\frac{\sqrt{3}a}{4}$ ( a = edge length)
$r=\frac{\sqrt{3}}{4}\times 351=151.8\text{pm},a=351\text{pm}$