Redox reactions play a pivotal role in chemistry and biology. The value of standard reduction potetials (E^(@)) of the two half cells reactions decide which way the reaction is expected to proceed. A simple example is of Daniell cell in which zinc goes into solution and copper gets deposited. Given below are a set of half-cell reactions (acidic medium) along with with E^(@) values. Using the data obtain the correct explanation to the questions that are mentioned. I_(2)+e^(-) to 2I^(-) , E^(@)=0.54" V " Cl_(2)+2e^(-) to 2Cl^(-) , E^(@)=1.36" V" Mn^(2+)+2e^(-) to Mn , E^(@)=1.50" V" Fe^(3+)+e^(-) to Fe^(2+) , E^(@)=0.77" V" O_(2)+4H^(+)+4e^(-) to 2H_(2)O , E^(@)=1.23" V". Sodium fusion extract obtained from aniline, on treatment with iron (II) sulphate and H_(2)SO_(4) in the presence of air, gives a prussian blue precipitate. The blue colour is due to the formation of :