For `M^(2+)//M and M^(3+)//M^(2+)` systems the `E^(@)` values for some metals are as follows:
`{:(Cr^(2+)//Cr,-0.9V,Cr^(3)//Cr^(2+),-0.4V),(Mn^(2+)//Mn,-1.2V,Mn^(3+)//Mn^(2+),+1.5V),(Fe^(2+)//Fe,-0.4V,Fe^(3+)//Fe^(2+),+0.8V):}`
Use this data to comment upon: (i) the stability of `Fe^(3+)` in acid solution as compared to that of `Cr^(3+)` or `Mn^(3+)` and
(ii) the ease with which iron can be oxidised as compared to a similar process for either chrmoium or magnganess metal.

Explanation

(i) The `M^(3+)|M^(2+)` values suggest that `Fe^(3+)` ions in acidic medium is more stable than `Mn^(3+)` ions and less stable than `Cr^(3+)` because of higher reduction potential.
(ii) `M^(2+)|M` is most negative for Mn and hence Mn will be most easily oxidized. The ease wiht which oxidation occurs will be `Mn gt Cr gt Fe`