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 : No of cotahedral voids = n
As alll the octahedral voids ar occupied by atoms X , therefore, number of atoms X = n .
Ratio of X :Y = n: n = 1:1.
Hence the formula of the compound is XY.