The edge lengths of the unit cells in terms of the radius of spheres constituting fcc, bcc and simple cubic unit cell respectively

Options

A. `2sqrt2r, (4r)/sqrt3, 2r`
B. `(4r)/sqrt3, 2sqrt2r , 2r`
C. `2r, 2sqrt(2r), (4r)/sqrt3`
D. `2r, (4r)/sqrt3 , 2sqrt2r`

Answer

a

Explanation

For fcc, `r=a/(2sqrt2)` or `a=2sqrt2` for bcc, `r=sqrt3/4a` or `a=4r//sqrt3`
For simple, r=a/2 or a=2r