Question

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

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

Answer 1

Answer: (B)

$128$

In F.C.C,

$a\sqrt{2}=4r$
$361\times \sqrt{2}=4r$
$r=128pm$