A solid AB has a rock salt structure . If radius of cation `A^+` is 120 pm, what is the minimum value of radius of `B^-` anion ?

Explanation

We know for the NaCl structure, for maximum of radius of `B^(-)`, the ratio `r^(+)//r^(-)` should be minimum for octahedral voild i.e., 0.414.
Radius of cation/radius of anion = 0.414
`(r_(A))/(r_(B)) = 0.414 rArr r_(B) = (r_(A))/(0.414) = (120)/(0.414) = 290` pm.