Using the standard electrode potential, find out the pair between which redox reaction is not feasible.
\[
\text{E}^\ominus \text{ values: } \text{Fe}^{3+}/\text{Fe}^{2+} = +0.77\text{ V}; \quad \text{I}_2/\text{I}^- = +0.54\text{ V}; \quad \text{Cu}^{2+}/\text{Cu} = +0.34\text{ V}; \quad \text{Ag}^+/\text{Ag} = +0.80\text{ V}
\]