An alloy of `Cu, Ag` and `Au` is found to have copper constituting the `c.c.p.` lattice. If `Ag` atom occupy the edge centres and `Au` atom is present at body centre, the formula of this alloy is `:`

Options

A. `Cu_(4)Ag_(3)Au`
B. `Cu_(4)Ag_(4)Au`
C. `Cu_(4)Ag_(3)Au`
D. CuAgAu

Answer

C

Explanation

In ccp arrangement, Cu atoms occupy the corners and face-centres.
`therefore` Number of Cu atoms `=8xx(1)/(8)+6xx(1)/(2)=4`
Number of silver atoms =Number of edge-centres `xx(1)/(4)=12 xx(1)/(4)=3`
Number of gold atoms=1(at body-centre)
`therefore` Formula of alloy `=Cu_(4)Ag_(3)Au`