Question

An alloy of copper and gold crystallizes in a cubic lattice in which the gold atoms occupy the lattice points at the corners of cube and copper atoms occupy the centre of each face. The formula of this compound is :

• A. $AuC{u}_3$
• B. AuCu
• C. $AuC{u}_2$
• D. $CuA{u}_3$

Answer 1

Answer: (A)

$AuC{u}_3$

Per unit cell, number of atoms of Cu $=\frac{1}{2}\times 6=3$
Number of atoms of Au $=\frac{1}{8}\times 8=1$
Therefore, the compound is ${\text{AuCu}}_3$.