Name the chemical compound which is electrolyzed in molten state to obtain sodium metal. Which gas is produced in this process ?

54 How are metals refined by the electrolytic process? Describe the electrolytic refining of copper with the help of a neat labelled diagram. 55 Name the chemical compound which is electrolyzed in molten state to obtain aluminium metal. Which gas is evolved during this process ? 55 Name the gas produced when calamine ore is calcined. 55 Name the gas evolved when cinnabar ore is roasted.