Given below are the half -cell reactions
`Mn^(2+)+2e^(-) to Mn, E^(@)=-1.18V`
`Mn^(3+)+e^(-) to Mn^(2+), E^(@)=+1.51 V`
The `E^(@)` for `3Mn^(2+)to Mn+2Mn^(3+)` will be _________.

Options

A. `-0.33V`, the reaction will occur
B. `-2.69V`, the reaction will not occur
C. `-2.69V`, the reaction will occur
D. `-0.33V`, the reaction will not occur

Answer

C

Explanation

The given cell reaction can be obtained from half-cell reactions as under:
`Mn^(2+)+2e^(-)toMn,E^(@)=-1.18V`
`underline(" "2Mn^(2+)to2Mn^(3+)+2e^(-),E^(@)=-1.51V)`
Overall reaction:
`3Mn^(2+)toMn+2Mn^(3+),E^(@)=-1.18V+(-1.51)`
`=-2.69V`
As `E_(cell)^(@)` is -ve, reaction will not occur.