Calculate the emf of the following three galvanic cells:
`l. Zn // Zn ^(2+) (1m) || Cu ^(2+) (1m) | Cu`
II. `Zn//Zn ^(2+) (0.1 ) || Cu ^(2+) ( 1m ) | Cu`
III. `Zn // Zn ^(2+) ( 1m ) || Cu ^(2+) (0.1m ) | Cu`
and their emf are represented by `E_(1), E_(2) and E_(3)` respectively .Which of the following emf order is true?

Options

A. `E _(1) gt E _(2) gt E _(3)`
B. `E _(3) gt E _(2) gt E _(1)`
C. `E _(3) gt E _(1) gt E _(2)`
D. `E _(2) gt E _(1) gt E _(3)`

Answer

D

Explanation

The cell reaction is
`Zn + Cu ^(2+) to Zn ^(2+) + Cu`
`E _("cell") = E _("cell") ^(@) - ( RT)/(nF) ln ""([Zn ^(2+)])/( [Cu ^(2+)])`
Greater the factor `[Zn ^(2+) ] //[Cu ^(2+)]`
less will be the EMF.