[" During the process of electrolytic refining of copper,some metals present as impurity settle as "],[" anode mud't These are "],[[" (1) Sn and Ag "," (2) Pb and Zn "],[[" (3) Ag and Au "," (4) Fe and Ni "]]],[[" (3) Ag and Au "," (4) Fe and Ni "," (MAINS- -2005) "]]