Question

Copper crystallises in a structure of face centred cubic unit cell. The atomic radius of copper is $1.28A^{\circ }$. What is the edge length of a unit cell of copper?

• A. $2.16A^{\circ }$
• B. $3.62A^{\circ }$
• C. $3.94A^{\circ }$
• D. $4.15A^{\circ }$

Answer 1

The correct option is B $3.62A^{\circ }$

Since it is FCC, we can establish the relation as: $a=\frac{4r}{\sqrt{2}}$
$a=\frac{4\times 1.28}{\sqrt{2}}=3.62A^o$