If `E_(1),E_(2)` and `E_(3)` are the emf values of the three galvanic cells respectivley
(i)`Zn|Zn^(2+)(1M)||Cu^(2+)(0.1M)|Cu`
(ii) `Zn|Zn^(2+)(1M)||Cu^(2+)(1M)|Cu`
(iii) `Zn|Zn^(2+)(0.1)||Cu^(2+)(1M)|Cu`.
Which one of the following is true.

Options

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

Answer

A

Explanation

`Zn+Cu^(2+)toZn^(2+)+Cu`
`E_(cell)=E_(cell)^(@)-(0.0591)/(2)"log"([Zn^(2+)])/([Cu^(2+)])`
Thus, higher the value of `[Zn^(2+)]//[Cu^(2+)]`, lower is the emf of the cell, `([Zn^(2+)])/([Cu^(2+)])` for `(i)=(1)/(0.1)=10`,
for (ii)`=(1)/(1)=1`, for `(iii)=(0.1)/(1)=0.1`
Hence, `E_(3) gt E_(2) gt E_(1)`.