Question

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

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

Answer 1

The correct option is D $128$

Since, $Cu$ crystallises in a face centered cubic lattice,
Atomic radius, $r=\frac{a}{2\sqrt{2}}(a=edgelength=361\text{pm})\therefore r=\frac{361}{2\sqrt{2}}=127.6=128\text{pm}$