Discuss whether the following phenomena are reversible ? (i) Whaterfall (ii) Rusting of iron and (iii) Electrolysis

Answer

(i) Waterfall. The falling of water is not a reversible process. During the fall of the water, the major part of its potential energy is converted into kinetic energy of the water. However, on striking the gound a part of potential energy is converted into heat and sound. it is not possible to convert the heat and the sound produced along with the `K.E`. of water into potential energy so that the water may rise back to its initial height. Therefore, waterfall is not a reversible process.
(ii) Rusting of iron. In the rusting of iron, the iron gets oxidised by the oxygen from the air. Since it is a chemical change, it is not a reversible process.
(iii) Electrolysis. It is reversible process. provided the electrolyte does not offer any resistance to the flow of current. If we reverse the direaction of current, the direaction of motion of ions is alos reversed.