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)=+0.80V`
Use this data to comment upon :
the stability of `Fe^(+3)` in acid solution as compared to `Cr^(+3)` or `Mn^(+3)`

Explanation

Higher the reduction potential of species, greater is the tendency for its reduction to take place. Therefore, `Mn^(+3)`, with the highest reduction potential would be readily reduced to `Mn^(+2) (Mn^(+3)+e to Mn^(+2))` and hence is least stable. Thus, from the values of reductions potential, it is clear that the stability of `Fe^(+3)` in acidic solution is more than `Mn^(+3)`, but less than that of `Cr^(+3)`.