Impurities of lead in silver all are removed by Amalgamation process
Silver is removed by the Parkes process, which consists of adding zinc to the molten lead bullion. Zinc reacts rapidly and completely with gold and silver, forming very insoluble compounds that float to the top of the bullion. These are skimmed off and their zinc content are recovered by These are skimmed off and their zinc content recovered by vacuum retorting. The remaining lead-gold-silver residue is treated by cupellation, a process in which the residue is heated to a high temperature (about 800 °C, or 1,450 °F) under strongly oxidizing conditions.
Hence a is the correct answer.