Give reasons for the following .
Iron pipes are usually , coated with zinc .

Explanation

As zinc lies above iron in the electrochemical series , it has a smaller standard reduction potential than iron , indicating that it has a higher tendency coated with zinc . This coating serves two purposes . These are (i) it prevents water and oxygen, which are essential for the rusting of iron to come in contract with the iron underneath (ii) under the condition of rusting , zinc in contact with iron acts as tha anode and loses electrons , whereas iron acts as the cathode . This happens because zinc has a higher tendency of oxidation than iron . So it will indergo oxidation in preference to iron . As iron remains passive towards oxidation , its corrosion is prevented in presence of zinc .