For M^(2+) //M and M^(3+) //M^(2+)system, E^(@) values for some metals are as follows , Cr^(2) //Cr= - 0.9 V l, Cr^(3+) //Cr^(2) = - 0.4 V, Mn^(2+) //Mn = - 1.2 V, Mn^(3+) //Mn^(2+) = + 1.5 V, Fe^(2+) //e= - 0.4 V, Fe^(3+) //Fe^(2+) = + 0.8 V Use this data to comment upon (i) the stability of Fe^(3+) in acid solution as compared to that of Cr^(3+) and Mn^(3+) (ii)the case with which iron can be oxidized as compared to the similar process for either Cr or Mn metals.

For M^(2+) //M and M^(3+) //M^(2+)system, E^(@) values for some metals

1.	For M^(2+) //M and M^(3+) //M^(2+)system, E^(@) values for some metals are as follows , Cr^(2) //Cr= - 0.9 V l, Cr^(3+) //Cr^(2) = - 0.4 V, Mn^(2+) //Mn = - 1.2 V, Mn^(3+) //Mn^(2+) = + 1.5 V, Fe^(2+) //e= - 0.4 V, Fe^(3+) //Fe^(2+) = + 0.8 V Use this data to comment upon (i) the stability of Fe^(3+) in acid solution as compared to that of Cr^(3+) and Mn^(3+) (ii)the case with which iron can be oxidized as compared to the similar process for either Cr or Mn metals.
Answer» Solution :(i) `Cr^(3+) //Cr^(2+)` has a negative reduction POTENTIAL. Hence, `Cr^(3+)` cannotbe reduced to `Cr^(2+) ` ,i.E, `Cr^(3+)` is most stable . `MN^(3+) //Mn^(2+)` has largepositive `E^(@)` value. Hence, `Mn^(3+)` can be easily reduced to `Mn^(2+)` , i.e., `Mn^(3+)` is least stable. `E^(@)` value for`Fe^(3+)//Fe^(2+)` is positivebut SMALL. Hence, `Fe^(3+) ` si more stable than `Mn^(3+)` but lessstable than `Cr^(3+)` (ii) Oxidation potentials for the givenpairs will be `+ 0.9 V , + 1.2 V` and `+ 0.4 ` volt . Thus, the ORDER of their getting oxidized will be in the order `Mn gt Crgt Fe`