Question

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

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

Answer 1

Answer: (A)

$128$

Answer 2

$Cu \rightarrow$ fcc lattice $4 r=\sqrt{2} a$ $r=\frac{1}{2 \sqrt{2}} a$ $r=\frac{1}{2 \sqrt{2}} \times 361=128$