In a close packed structure of mixed oxides, the lattice is composed of oxide ions, one- eighth of tetrahedral voids are occupied by divalent cations 'A' while one- half of octahedral voids are occupied by trivalent cations 'B'. The formula of the oxide is

Explanation

Let there be n no. of `O^(2-)` in the crystal.
`therefore` Octahedra voids = n
Tetrahedral voids = 2n
`A^(2+)"ions"=(1)/(8)xx2n=(n)/(4)," "B^(3+)"ion=(1)/(2)xxn=(n)/(2)`
`A^(2+):B^(3+):O^(2-)=(n)/(4):(n)/(2):n" "=1:2:4`
`therefore"formula is"AB_(2)O_(4)`