For I2+2e→2I-, standard reduction potential = + 0.54 volt. For 2Br-→Br2+2e-, standard oxidation potential = – 1.09 volt. For Fe→Fe2++2e-standard oxidation potential = + 0.44 volt. Which of the following reactions is non-spontaneous?

A redox reaction in which SRP of oxidising agent is lesser than SRP of reducing agent is non-spontaneous and does not occurs. Alternatively, If Ecell comes to be negative the reaction is non-spontaneous and does not occur.For option (4), E0= E0(Cathode)-E0(anode)= +0.54V-1.09V=-0.55V ;