# An ionic compound AB has ZnS type of structure, if the radius A+ is  22.5 pm , then the ideal radius of B- is

Q: An ionic compound AB has ZnS type of structure, if the radius A+ is  22.5 pm , then the ideal radius of B is

(A) 54.35 pm

(B) 100 pm

(C) 145.16 pm

(D) None

Solution:    Since ionic compound AB has ZnS type of structure, therefore it has tetrahedral holes, for which,

$\large \frac{radius \; of\; cation}{radius \; of\; anion} = 0.225$

$\large \frac{r_+}{r_-} = 0.225$

$\large \frac{22.5}{r_-} = 0.225$

Hence, r = 100 pm

Ans: (B)