What elements are present in steel? How are the properties of steel different from those of pure iron?

47 What is meant by 'rusting of iron'? With the help of labelled diagrams, describe an activity to find out the conditions under which iron rusts. 48 What is an alloy ? How is an alloy made? 48 Give the constituents and one use of brass. 49 Name two metals which resist corrosion due to the formation of a thin, hard and impervious layer of oxide on their surface.