A compound is formed by two elements `X` and `Y`. Atoms of the element `Y` (as anion) make ccp and those of element `X` (as cation) occupy all the octahedral voids. What is the formula of the compound?

Explanation

Suppose number of atoms Y in ccp=n
As number of octahedral voids = No. of atoms in ccp `therefore` No. of octahedral voids=n
As all the octahedral voids are occupied by atoms X, therefore , number of atoms X=n
`therefore` Ratio of X :Y =n:n=1:1
Hence the formula of the compound is XY