Copper displaces which of the following metals from their salt solutions?

Which one of the following is the correct plot of $\Lambda_m$ (in $S \ cm^2 \ mol^{-1}$) and $\sqrt{C}$ (in $mol^{1/2} \ L^{-1/2}$) for a $KCl$ solution? ($y=\Lambda_m$; $x=\sqrt{C}$)

Adding powdered lead and iron to a solution that is $1.0 \ M$ in both $Pb^{2+}$ and $Fe^{2+}$ ions would result in a reaction in which:

Which of the following statements about a galvanic cell is incorrect?

Based on the reaction $\frac{4}{3} \, Al + O_2 \to \frac{2}{3} \, Al_2O_3$,with $\Delta G = -827 \, kJ \, mol^{-1}$ of $Al_2O_3$,what is the minimum $e.m.f.$ required for the electrolysis? $(F = 96500 \, C \, mol^{-1})$

$A$ button cell used in watches functions as follows:
$Zn_{(s)} + Ag_2O_{(s)} + H_2O_{(l)} \rightarrow 2Ag_{(s)} + Zn^{2+}_{(aq)} + 2OH^{-}_{(aq)}$
If the half-cell potentials are:
$Zn^{2+}_{(aq)} + 2e^- \rightarrow Zn_{(s)} \,;\, E^o = -0.76 \, V$
$Ag_2O_{(s)} + H_2O_{(l)} + 2e^- \rightarrow 2Ag_{(s)} + 2OH^{-}_{(aq)} \,;\, E^o = 0.34 \, V$
The cell potential will be $..........$ $V.$