Question

Lthium metal 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 :-
($\sqrt{3}=1.732$)

• A. $300.5\text{pm}$
• B. $240.8\text{pm}$
• C. $149.17\text{pm}$
• D. $75.5\text{pm}$

Answer 1

The correct option is C $149.17\text{pm}$

In BCC,
$Z=1$
$a=351pm$
For, BCC,
$a=\frac{4r}{\sqrt{3}}$
$r=\frac{\sqrt{3}a}{4}=\frac{1.732\times 351}{4}=151.98pm$