By which method/process is sulphur obtained from the earth's crust?

$(i)$ Explain the steps for extraction of copper from its sulphide ore. Write the balanced equations involved in the process.
$(ii)$ What is meant by refining of metals? Draw a diagram of electrolytic refining of copper and name the substances used as cathode, anode, and the electrolyte.

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

In the froth flotation process,which particles get wetted by turpentine and rise to the surface of the liquid mixture with the froth?

Which method is used for the purification of semiconductor metals?

Metals are refined by using different methods. Which of the following metals are refined by electrolytic refining?
$(i)$ $Au$
$(ii)$ $Cu$
$(iii)$ $Na$
$(iv)$ $K$