Question

Lithium metal crystallises in a body centred cubic
crystal. If the length of the side of the unit cell of
lithium is 351 pm, the atomic radius of the lithium
will be:
(a) 151.8 pm (b) 75.5 pm
(c) 300.5 pm (d) 240.8 pm

Answer 1

(a) 151.8 pm

Explanation:

Given Edge Length = 351 pm

For bcc structure, a​√3 = 4r

So r = a√3/4 = 351 * √3 / 4 = 151.98 pm

Among the given options, the closest value is 151.8 pm.

Hence Option A is the answer.