Question

An alloy of copper, silver and gold is found to have copper forming the cubic closed pack lattice. If silver atoms occupy the edge centers and gold is present at the body centre, the alloy will have the formula:

• A. $C{u}_{4}A{g}_{2}Au$
• B. $C{u}_{4}A{g}_{4}Au$
• C. $C{u}_{4}A{g}_{3}Au$
• D. $CuAgAu$

Answer 1

The correct option is C $C{u}_{4}A{g}_{3}Au$


Total number of $Cu$ - atoms in a unit cell
$=8\times \frac{1}{8}+6\times \frac{1}{2}$
$=1+3=4\text{atoms}$
Total number of silver atoms in a unit cell
$=12\times \frac{1}{4}=3\text{atoms}$
Total gold atoms in a unit cell $=1\text{atoms}$
Hence the formula ia $C{u}_{4}A{g}_{3}Au$