How is the thermodynamic efficiency of a cell defined?

In a $Cu-Zn$ electrochemical cell:

In the reaction $Cu_{(s)} + 2Ag^{+}_{(aq)} \to Cu^{2+}_{(aq)} + 2Ag_{(s)}$,the reduction half-cell reaction is:

Given below are two statements: one is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A$: In equation $\Delta_r G = -nFE_{\text{cell}}$,the value of $\Delta_r G$ depends on $n$.
Reason $R$: $E_{\text{cell}}$ is an intensive property and $\Delta_r G$ is an extensive property.
In the light of the above statements,choose the correct answer from the options given below:

The $Cu^{+}$ ion is not stable in aqueous solution. For the disproportionation reaction,what is the $E^o$ value in $V$? (Given: $E^o_{Cu^{2+} | Cu^{+}} = 0.15 \, V$; $E^o_{Cu^{2+} | Cu} = 0.34 \, V$)

Which of the following is an incorrect statement?