Which method/process is used to obtain aluminium from pure alumina?

Which of the following reactions is called roasting?

In the electrolytic refining of metals, the insoluble impurities present in the impure metal settle down at the bottom of the container below the anode. What is this called?

In the electrolytic refining of a metal $M$,what would you take as the anode,the cathode,and the electrolyte?

Name the ore of mercury. How is mercury extracted from its ore?

Which of the following metals exist in their native state in nature?
$(i)$ $Au$
$(ii)$ $Cu$
$(iii)$ $Ag$
$(iv)$ $Fe$