For `M^(2+)//M and M^(3+)//M^(2+)` systems the `E^(Theta)` 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,-0.4" "Fe^(3+)//Fe^(2+),+0.8V):}`
Use this data to comment upon:
(i) the stability of Fe3+ in acid solution as compared to that of Cr3+ or Mn3+ and
(ii) the ease with which iron can be oxidised as compared to a similar process for either chromium or manganese metal.