An alloy of copper, silver and gold is found to have copper constituting the ccp lattice. If silver atoms occupy the edge centres and gold is present at body centre, the alloy will have the formula:

Effective no. of Cu in a unit cell =8×18+6×12=4Effective no. of Ag in a unit cell =12×14=3Effective no, of Au in a unit cell = 1Effective no, of Au in a unit cell = 1So, general formula of compound is Cu4Ag3Au