Copper can best be purified by

Copper can best be purified by electrolyzing a copper (ll) salt solution using the impure copper as the anode. Electrolysis is a process in which an electric current is passed through a solution containing ions, causing them to move towards the electrodes. In this case, the impure copper is used as the anode, and the cathode is made of pure copper. As the current passes through the solution, the impure copper anode dissolves, and the copper ions move towards the cathode and are deposited as pure copper. This process allows for the removal of impurities from the copper, resulting in a higher level of purity than other methods such as roasting or heating with coke.