Standard electrode potentials are
`Fe^(2+)//Fe, E^(@) = -0.44 V`
`Fe^(3+)//Fe^(2+), E^(@) = +0.77 V`
If `Fe^(3+), Fe^(2+)`, and Fe block are kept together, then

Options

A. increase in `Fe^(3+)`
B. decrease in `Fe^(3+)`
C. `Fe^(2+)//Fe^(3+)` remains unchanged
D. `Fe^(2+)` decreases

Answer

b

Explanation

Higher is the `E^(@)` stronger is the oxidising agent thus `Fe^(3+)` with `E^(@)=0.77V` is the stronger oxidising agent
`Fe^(3+)+e^(-)rarrFe^(2+)`
Thus the amount of `Fe^(3+)` will decrease