A compound of A and B crystallizes in a cubic lattice in which A atoms occupy the lattice points at the corners of a cube and two atoms of B occupy the center of each of the cube faces. What is the formula of this compound?

Explanation

One-eighth of each corner atom (Au) and one- half of each face-centered atom (Cu) are contained with in the unit cell of the compound. Thus, the number of Au atoms per unit cell = 8
`xx(1)/(8)=1` and the number of Cu atoms per unit
cell=`6xx(1)/(2)=3`. the formula of the compound is `AuCu_(3)`