In a crystalline solid, anions `B` are arranged in ccp structure. Cations `A` are equally distributed between octahedral and tetrahedral voids if all the octahedral voids are occupied the formula of the ionic solids will be

Answer

`X_2Y`

Explanation

Suppose the number of anions Y = N
No. of octahedral voids = N
No. of tetrahedral voids = 2N
Since octaheral and tetrahedral voids are equally occupied by cation X and all the octahedral voids are occupied (as given) then N cations X are present in octahedral voids and N cations X are present in tetrahedral voids. Therefore,
No. of cations present = N + N = 2N
Ratio of cations X and anions `Y = 2N : N`
or `2 : 1`
Thus, the formula of the compound will be `X_2Y`.