CGPET 2018 Solved Paper

Edge length (a) and radius of sphere (r) in a body centered cubic unit cell are related with each other in the following manner.
Given, √3a=4r
r=1.857×10−8cm
Thus, a=

4×1.857×10−8

√3

or a=

4×1.857×10−8

1.73

a=4.29Å
Hence, (b) is the correct option.