Agl crystallises in cubic close packed ZnS structure. What fraction of tetrahedral sites are occupied by Ag+ ions?
In AgI, if there are nI- ions, there will be nAg+ ions. As I- ions form the lattice, number of tetrahedral voids = 2n.
As there are nAg+ ions to occupy these voids, therefore fraction of tetrahedral voids occupied by Ag+ ions = n/2n = ½ = 50%.