Name the metal which is extracted from the ore called 'rock salt'.

59 Explain why, the galvanized iron article is protected against rusting even if the zinc layer is broken. 59 Name a common metal which is highly resistant to corrosion. 60 Name two ores of zinc. Write the names of the chemical compounds present in them and give their chemical formulae. 60 Explain how, mercury is extracted from its sulphide ore (cinnabar). Give equations of the reactions involved.