For the cell reaction,$Cu | Cu^{2+}(0.1 \ M) || Cu^{2+}(1.0 \ M) | Cu$,the emf of the cell at $25^{\circ}C$ is given that $E^{\circ}_{Cu^{2+}/Cu} = 0.34 \ V$. (in $V$)

The $e.m.f.$ of the following galvanic cells are represented by $E_1, E_2, E_3$ and $E_4$. Which of the following statements is true?
$(i)$ $Zn|Zn^{2+} (1 \, M)||Cu^{2+} (1 \, M)|Cu$
$(ii)$ $Zn|Zn^{2+} (0.1 \, M)||Cu^{2+} (1 \, M)|Cu$
$(iii)$ $Zn|Zn^{2+} (1 \, M)||Cu^{2+} (0.1 \, M)|Cu$
$(iv)$ $Zn|Zn^{2+} (0.1 \, M)||Cu^{2+} (0.1 \, M)|Cu$

For the given cell $Cu(s) | Cu^{2+}(C_1 \ M) || Cu^{2+}(C_2 \ M) | Cu(s)$,the change in Gibbs energy $(\Delta G)$ is negative,if:

$E_{1}$,$E_{2}$ and $E_{3}$ are the emfs of the following three galvanic cells respectively.

Derive an equation for the equilibrium constant $K_C$ of any galvanic cell (redox reaction) and also state its uses.

Considering the cell $Cu | Cu^{2+} || Ag^{+} | Ag$,what happens to the $emf$ if the concentrations of both $Cu^{2+}$ and $Ag^{+}$ ions are increased by a factor of $10$?