What is the change in oxidation number of $Pb$ at the positive electrode of a lead accumulator acting as a galvanic cell?

Which of the following statements is true for an electrolytic cell?

Which one of the following reactions does not take place?

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:

What are reactive electrodes and inert electrodes? Give examples.

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 $............... \ V$