In a crystalline solid, anions B are arranged in a cubic close packing. Cations A are equally distrilbuted between octahedral and tetrahedral voids. If all the octahedral voids are occupied, what is the formula of the solid ?

In a crystalline solid, anions B are arranged in a cubic close packing

1.	In a crystalline solid, anions B are arranged in a cubic close packing. Cations A are equally distrilbuted between octahedral and tetrahedral voids. If all the octahedral voids are occupied, what is the formula of the solid ?
Answer» Solution :Suppose the number of anions B = n. Then number of OCTAHEDRAL voids = n . Number of tetrahedral voids = 2n. As octahedral and tetradhedral voids are equally occupied by cations A and all the octahedral voids are occupied (given)THEREFORE, n capitan A are PRESENT in octahedral voids and n cationsA are present in tetrahedral voids. In other WORDS, correshponding to n anions B , there are n +n = 2n cations A. Thus, A and anuions B are in the ratio 2n: n =2 : 1 hence, the FORMUAL of the solid will be `A_(2) B` .