1. | A layer of cupric oxide on the surface of copper. |
2. | Basic copper sulphate layer on the surface of the metal. |
3. | A layer of cupric hydroxide on the surface of copper. |
4. | A layer of basic carbonate of copper on the surface of copper. |
1. | \(SO^{2-}_3\) | 2. | \(NO^{-}_2\) |
3. | \(S^{2-}\) | 4. | All of the above |
1. | \(\mathrm{NO}_2^{-} \) | 2. | \(\mathrm{NO}_3^{-} \) |
3. | \(\mathrm{Br}^ - \) | 4. | \(\mathrm{SO}_3{ }^{2-}\) |