Question

Copper crystallise in $fcc$ with a unit cell length of $361pm$. What is the radius of copper atom?

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

Answer 1

The correct option is C $127pm$

For $fcc$ crystal,

$a=2\sqrt{2}r$

$r=\frac{a}{2\sqrt{2}}$

$r=\frac{361}{2\sqrt{2}}$

$r=127.6pm$.

Hence, option "C" is the correct answer.