Atoms of elements `B` from hcp lattice and those of element `A` occupy two-thirds of tetrahedral voids. What is the formula of the compound formed by elements `A` and `B`?

Explanation

Suppose number of atoms B in hcp lattice =n
As number of tetrahedral voids is double the number of atoms in the close packing , therefore, number of tetrahedral voids =2n
As atoms A occupy 2/3rd of the tetrahedral voids, therefore, number of atoms A in the lattice =`2/3xx2n="4n"/3`
`therefore` Ratio of A:B=`"4n"/3:n=4/3:1=4:3`
Hence, the formula of the compound `A_4B_3`