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

Since ionic compound AB has ZnS type of structure with co-ordination number 4;4.F or co-ordination number 4 the radius ratio should range between 0.22 to 0.41.radius of cationradius of anion=0.225r+r-=0.22522.5r-=0.225Hence, r-=100pm