Using the standard electrode potential, find out the pair between which redox reaction is not feasible.
E°Values: Fe3+/ Fe2+ = +0.77; I2/I- = +0.54;
Cu2+/ Cu = -0.34; Ag+ /Ag = + 0.80 V
(i) Fe3+ and I-
(ii) Ag+ and Cu
(iii) Fe3+ and Cu
(iv) Ag and Fe3+
Option (iv) Ag and Fe3+ is the answer.