A compound of formula `A_(2)B_(3)` has the hcp lattice. Which atom forms the hcp lattice and what fraction of tetrahedral voids is occupied by the other atoms

Options

A. hcp lattice - A , `2/3` Tetrahedral voids - B
B. hcp lattice - B , `1/3` Tetrahedral voids - A
C. hcp lattice - B, `2/3` Tetrahedral voids-A
D. hcp lattice - A, `1/3` Tetrahedral voids - B

Answer

B

Explanation

`A_2B_3` has hcp lattice.
If A atoms form hcp, then `3/4` of the tetrahedral voids are occupied by B to form `A_2B_3`.
If B atoms forms hcp, then `2/6` or `1/3` of tetrahedral voids are occupied by A atoms to form `A_2B_3`.