In a crystalline solid, having formula XY₂O₄, oxide ions are arranged in cubic close packed lattice while, cations X are present in tetrahedral voids and cations Y are present in octahedral voids. The percentage of tetrahedral voids occupied by X is (JIPMER 2018)

In a cubic close packed lattice of oxide ions, there would be two tetrahedral and one octahedral void per oxide ion. Since, the formula shows the presence of 4 oxide ions, the number of tetrahedral voids is eight and that of octahedral voids is four. Out of the eight tetrahedral voids, one is occupied by X. percentage of tetrahedral voids occupied SOLID STATE 33 1 100 12.5% 8 x