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 : sqrt3/4a : 1/(2sqrt2)a`
B. `1/2a:sqrt3a:1/sqrt2a`
C. `1/2a:sqrt3/2a:sqrt2/2a`
D. `1a:sqrt3a: sqrt2a`

Answer

A

Explanation

For simple cubic , `r=a/2`
for bcc , `r=(sqrt(3)a)/(4)`
For fcc , `r=(a)/(2sqrt2)`
Therefore, the ratio of radii of scc , bcc and fcc
`=a/2 : (sqrt3)/(4)a:(a)/(2sqrt2)`