Which of the following is $NOT$ true about a voltaic cell?

Which of the following reactions is correct for a given electrochemical cell at $25^{\circ} C$ ?
$Pt | Br_{2(g)} | Br_{(aq)}^{-} || Cl_{(aq)}^{-} | Cl_{2(g)} | Pt$

Efficiency of a cell with cell reaction under standard conditions,$A_{(s)} + B^{+} \to A^{+} + B_{(s)}$; $\Delta H^o = -300 \ kJ$ is $70\%$. The standard electrode potential of the cell is :- .................... $V$

On the basis of the information available from the reaction $\frac{4}{3} Al + O_2 \to \frac{2}{3} Al_2O_3$,$\Delta G = -827 \ kJ \ mol^{-1}$ of $O_2$,the minimum emf required to carry out an electrolysis of $Al_2O_3$ is $............... \ V$

Which substance is used as an oxidising agent in a nickel-cadmium cell?

Which option is incorrect for the working cell? $Pt \mid Cl_{2(g, 1 \ bar)} \mid Cl_{(C_1)}^{-} \parallel Cl_{(C_2)}^{-} \mid Cl_{2(g, 1 \ bar)} \mid Pt$