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

Explanation

(B) gm EqA= gm Eq B = gm EqC
`2.1/(7/x)=2.7/(27/y)=7.2/(48/z)` , 0.3x=0.1y=0.15z
3x=y=1.5z
x=2, y=6, z=3