For `Mn^(3+)//Mn^(2+)` system, the `E^(0)` values for some metals are as follows:
`Cr^(3+)//Cr^(2+)(-0.4V) , Mn^(3+)//Mn^(2+) (+1.5V)`,
`Fe^(3+)//Fe^(2+)(+0.8V)`. Then the relative stabilities of `Fe^(3+), Cr^(3+)` and `Mn^(3+)` is :

Options

A. `Mn^(3+) lt Fe^(3+) lt Cr^(3+)`
B. `Fe^(3+) lt Mn^(3+) lt Cr^(3+)`
C. `Cr^(3+) lt Fe^(3+) lt Mn^(3+)`
D. `Fe^(3+) lt Cr^(3+) lt Mn^(3+)`

Answer

A

Explanation

`E_(Cr^(3+)//Cr^(2+))` is negative `(-0.4V)` . Its shows that stability of `Cr^(3+)` ions i.e., `Cr^(3+)` in solution can not be reduced to `Cr^(2+)` ions. Further `Mn^(3+)` has high positive `E^(0)` value. So it is easily converted of `Mn^(2+)` as compared to the conversion of `Fe^(3+)` to `Fe^(2+)` thus, the order of relative stablities of different ions is :
`Mn^(3+) lt Fe^(3+) lt Cr^(3+)`