What are the different types of metallurgy involved?

The sketch given below illustrates the refining of aluminium by Hoope’s process.
 
(i) Which among $\mathrm{A}$ and $\mathrm{B}$ is the cathode and which one is anode?

(ii) What is the electrolyte in the tank?

(iii) Which material is used for the cathode?

Following is the sketch of electrolytic cell used in the extraction of aluminium.

(i) Name the substance of which electrodes $\mathrm{A}$ and $\mathrm{B}$ are made?

(ii) At which electrode ($\mathrm{A} \mathrm{or} \mathrm{B}$) is the aluminium formed?

(iii) What are the two aluminium compounds in the electrolyte $\mathrm{C}$?

(iv) Why is it necessary for electrode $\mathrm{B}$ to be continuously replaced?