Give the name and chemical formula of one ore of copper.

36 Explain why, though aluminium is more reactive than iron, yet there is less corrosion of aluminium when both are exposed to air. 37 Name the method by which aluminium metal is extracted. 37 How is zinc extracted from its carbonate ore (calamine)? Explain with equations. 38 Name two metals which occur in nature in free state as well as in combined state.