What type of oxide is aluminium oxide $(Al_2O_3)$?

Although metals form basic oxides,which of the following metals form an amphoteric oxide?

Which process is used to obtain metal from metal oxide?

When excess water is added to sodium aluminate and stirred continuously,it undergoes hydrolysis to form white gelatinous precipitates of which substance?

Why should metal sulphides and carbonates be converted to metal oxides during the process of metal extraction?

$(i)$ Define the term 'anode mud'. Name the electrode made of pure metal.
$(ii)$ Give the reactions taking place at cathode and at anode during the electrolytic refining of copper.