Which of the following statements is true regarding electrolytic refining of copper?
Correct: D
In electrolytic refining of copper, the impure copper is made the anode, and a thin sheet of pure copper is made the cathode. The electrolyte used is an acidic solution of copper sulphate. During electrolysis, copper from the anode dissolves and deposits on the cathode as pure copper. More reactive impurities from the anode also dissolve in the electrolyte but do not deposit on the cathode, while less reactive impurities (like gold, silver, platinum) do not dissolve and fall to the bottom as anode sludge.