Question

Copper crystallises in fcc with a unit cell length of 361 pm. What is the radius of copper atom?

• A. 127 pm
• B. 157 pm
• C. 181 pm
• D. 108 pm

Answer 1

Answer: (A)

127 pm

For FCC , relationship between radius(r) and unit cell length(a) is :

r = $\frac{a}{2\sqrt{2}}$

a = 361 pm ,

Hence , r = $\frac{361}{2\sqrt{2}}$

r = 127 pm