A binary solid `(A^(+)B^(+))` has a rock sell structure .If the edge length is `400 pm` and radius of cation is 75 pm the radius of amion attion is

Options

A. 100 pm
B. 125 pm
C. 250 pm
D. 325 pm

Answer

B

Explanation

`2r^(+)+2r^(-)=400 or r^(+)+r^(-)=200`
`or r^(-)=200-r^(+)`
`or r^(-)=200-75=125`.