The standard electrode potential of copper is positive. Which of the following statements is true?

\(Cu\) is oxidized by nitrate ion in nitric acid

The correct answer is option 3. \(Cu\) is oxidized by nitrate ion in nitric acid.

Standard electrode potential of copper: The standard electrode potential of copper \((Cu/Cu^{2+})\) is \(+0.34 V\). This positive value indicates that copper is a good oxidizing agent in standard conditions.

Analysis of statements:

1. \(H^+\) ions get reduced more easily than \(Cu^{2+}\) ions: This statement is false. Since copper has a positive electrode potential, it has a greater tendency to attract electrons and undergo reduction compared to \(H^+\) ions in standard conditions. Therefore, \(Cu^{2+}\) ions are reduced more easily than \(H^+\) ions.
2. \(Cu\) does not dissolve in \(HCl\): This statement is false. Dilute \(HCl\) can dissolve copper due to the formation of \(CuCl_2\) complexes. The reaction is:

\[Cu + 2 HCl \longrightarrow CuCl_2 + H_2\]

3. \(Cu\) is oxidized by nitrate ion in nitric acid: This statement is true. Concentrated nitric acid \((HNO_3)\) can oxidize copper to \(Cu^{2+}\) ions due to the strong oxidizing ability of the nitrate ion \((NO_3^-)\). The reaction is:

\[Cu + 4 HNO_3 \longrightarrow Cu(NO_3)_2 + 2 NO_2 + 2 H_2O\]

4. \(H^+\) ions cannot oxidize copper: This statement is false. As mentioned earlier, copper has a positive electrode potential, making it susceptible to oxidation by species with lower reduction potentials. Under appropriate conditions (e.g., concentrated solutions or the presence of oxidizing agents), \(H^+\) ions can oxidize copper.