${\rm{C}}{{\rm{u}}^ + }\left( {aq} \right)$ is unstable in solution and undergoes simultaneous oxidation and reduction, according to the reaction<br />$2{\rm{C}}{{\rm{u}}^ + }\left( {aq} \right)\leftrightharpoons{\rm{C}}{{\rm{u}}^{2 + }}\left( {aq} \right) + {\rm{Cu}}\left( s \right)$<br />choose correct ${E^ \circ }$ for the above reaction if<br />$E_{{\rm{C}}{{\rm{u}}^{2 + }}/{\rm{Cu}}}^ \circ = 0.34{\rm{V}},E_{{\rm{C}}{{\rm{u}}^{2 + }}/{\rm{C}}{{\rm{u}}^ + }}^ \circ = 0.15{\rm{V}}$