Correct Answer - Copper is extracted by hydrometallurgy from low grade copper ores. It is leached out using acid or bacteria The solution containing `Cu^(2+)` is treated with scrap iron, `Zn` or `H_(2)`
`2Cu^(2+) (aq) + H_(2)(g) rarr 2Cu(s) +2H^(+) (aq)`
`Cu^(2+) +Fe(s) rarr Fe^(2+) (aq) + Cu(s)`