Question

Copper crystallises in face centred cubic lattice with a unit all length of $361pm$. What is the radius of copper atom in $pm$?

• A. $128$
• B. $157$
• C. $181$
• D. $108$

Answer 1

The correct option is A $128$

In FCC unit cell,

$4r=a\sqrt{2}$ (along the face diagonal)

$a=361$ $pm$

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

$⟹r=128$ $pm$