The radius of `Na(+)` is 95 pm and that of `CI^(-)`ions is 181 pm. Predict whethr the coordination number of `Na^(+)` is 6 or4.

Explanation

Radius ratio `((r^(+))/(r^(-)))=(95)/(181)=0.52`
Radius ratio lies between `0.414-0.732`, hence `Na^(+)` ions prefer to occupy octahedral voids having Co - ordination Number = 6.