Question

An element possess cubic close packing structure. Calculate the radius $\left(r\right)$ of the atom in the unit cell.

(The edge length of the unit cell is $a=252nm$)

• A. $126nm$
• B. $152nm$
• C. $89.36nm$
• D. $109.1nm$

Answer 1

Answer: (C)

$89.36nm$

In cubic closed pack structure, the face diagonal of the cube is $4\times r$ where $r$ is the radius of the atom

Face Diagonal of CCP=$\sqrt{2}\times a$

thus, $\sqrt{2}\times a=4\times r$

$\sqrt{2}\times 252=4\times r$

$r=89.1nm$

Hence, option $C$ is correct.