Question

Copper crystallises in F.C.C. with a unit cell length of 361 pm. What is the radius of copper atom?

• A. 108 pm
• B. 127 pm
• C. 157 pm
• D. 181 pm

Answer 1

The correct option is B 127 pm

For, FCC, $\sqrt{2}a$ = 4r(the atoms touches each other along the face diagonal)
$r=\frac{\sqrt{2}a}{4}=\frac{\sqrt{2}\times 361}{4}=127pm$