Spelter is

During the electrolytic reduction of alumina,the reaction at the cathode is:

Identify $A$ and $B$ respectively in the following reactions:
$4 Au_{(s)} + 8 CN^{-}_{(aq)} + 2 H_2O_{(aq)} + O_{2(g)} \longrightarrow 4 A_{(aq)} + 4 OH^{-}_{(aq)}$
$2 A_{(aq)} + Zn_{(s)} \longrightarrow B_{(aq)} + 2 Au_{(s)}$

Cast iron is used for the manufacture of

During the extraction of sodium metal by electrolysis,a mixture of $40\%$ molten $NaCl$ and $60\%$ $CaCl_2$ is used because .......

Explain the electrolytic reduction of alumina.