Copper is refined by A. Roasting B. Oxidation C. Electrolysis D. Zone refining

The correct answer is C. Electrolysis.

Roasting is a process of heating ores in air to remove volatile components. Oxidation is a process of combining a substance with oxygen. Zone refining is a process of purifying a material by passing an electric current through a rod of the material.

Electrolysis is a process of using an electric current to separate materials. In the case of copper refining, the copper is dissolved in a solution of sulfuric acid and then an electric current is passed through the solution. The copper ions are attracted

to the cathode, where they are reduced to copper metal. The impurities in the copper are not attracted to the cathode and are left in the solution.

Electrolysis

is the most common method of refining copper because it is a very efficient process. It can remove impurities from copper to a very high degree of purity.