Correct Option (c) X4 Y5 O10
In ccp, anions occupy all lattice points of the cube while cations occupied voids. In ccp, there are two
tetrahedral voids and one octahedral hole.
For one oxygen atom, there are two tetrahedral holes and one octahedral hole. Since one fifth of the tetrahedral
voids are occupied by divalent cations (X2+).
:. number of divalent cations in tetrahedral voids = 2 x 1/5.
Since half of the octahedral voids are occupied by trivalent cations (Y3+)
:. Number of trivalent cations = 1x 1/2.
.So the formula is the compound is (X)2 x 1/5 (Y)1/2 (O)1
or X2/5 Y1/2 O1