Question

A given metal crystallizes out with a cubic structure having edge length of 361 pm. If there are four metal atoms in one unit cell, what is the radius of one atom?

• A. 108 pm
• B. 40 pm
• C. 127 pm
• D. 80 pm

Answer 1

The correct option is

C

127 pm

Since there are 4 atoms in a unit cell, we can assume that it is an FCC structure.

$4r=\sqrt{2}a$

$r=\frac{\sqrt{2}a}{4}=\frac{\sqrt{2}\times 361}{4}=127pm$

Edge-centred and FCC are considered the same.