The edge length of a face-centred cubic unit cell is `508 pm`. If the radius of the cation is `110 pm` the radius of the anion is

Options

A. 285 pm
B. 398 pm
C. 144 pm
D. 618 pm

Answer

C

Explanation

Distance between centres of cation and anion
`=(d)/(2)=(508)/(2)=254 p m " ":.d=r^(+)+r^(-)`
`:.r^(-)d-r^(+)=254-110=144`