3.5 CORROSION

. CORROSION You hav e learnt the following about corrosion in Chapter – n Silver articles become black after some time when exposed to air. This is because it reacts with sulphur in the air to form a coating of silver sulphide. n Copper reacts with moist carbon dioxide in the air and slowly loses its shiny brown surface and gains a green coat. This green substance is basic copper carbonate. n Iron when exposed to moist air for a long time acquires a coating of a brown flaky substance called rust. Let us find ou t the conditions under which iron rusts. A B C