AgI crystallises in cubic close packed ZnS structure. What fraction of tetrahedral sites is occupied of Ag^+ ions ?

AgI crystallises in cubic close packed ZnS structure. What fraction of

1.	AgI crystallises in cubic close packed ZnS structure. What fraction of tetrahedral sites is occupied of Ag^+ ions ?
Answer» Solution :In the face-centred unit cell of AGI, there are `4 Ag^+` ions and `4 I^-` ions. As there are `4 I^-` ions in the PACKING. Therefore, there are eight tetrahedral VOIDS. Of these , half are occupied by silver cations.