# When the sample of copper with zinc impurity is to be purified by electrolysis, the appropriate electrodes are?

$(a)\;\text{pure zinc pure copper } \\(b)\;\text{impure sample pure copper} \\(c)\;\text{impure zinc impure sample} \\ (d)\;\text{pure copper impure sample.}$

The sample of copper with zinc impurity is to be purified by electrolysis, the appropriate electrodes are pure copper impure sample.
Hence d is the correct answer.