If `'a'` stands for the edge length of the cubic systems: simple cubic,body centred cubic and face centred cubic then the ratio of radii of the spheres inthese systems will be respectively,

Options

A. `1/2a: sqrt(3)/2a: sqrt(2)/a`
B. `1a : sqrt(3)a : sqrt(2)a`
C. `1/2a : sqrt(3)/4a : 1/(2sqrt(2))a`
D. `1/2a: sqrt(3)a : 1/sqrt(2)a`

Answer

C

Explanation

`scc alpha = 2r`
`bcc sqrt(3)a = 4r`
`fcc sqrt(2)a = 4r`
`a/2: (sqrt(3)a)/4 : (sqrt(2)a)/4`