Question

Atoms of an element $Z$ form hexagonal closed packed (hcp) lattice and atoms of element $X$ occupy all the tetrahedral voids. The formula of the compound is

• A. $XZ$
• B. $X{Z}_2$
• C. $X_{2}Z$
• D. $X_4{Z}_3$

Answer 1

Answer: (C)

Number of lattice points in a $hcp$ lattice : number of tetrahedral voids is in $1:2$ ratio.
$\therefore$ Number of $Z$ atoms : $X$ atoms = $1:2$
$\therefore$ Formula of compound = $X_{2}Z$