question_answer 23)

  Rusting of an article made up of iron is called (a) corrosion and it is a physical as well as chemical change (b) dissolution and it is a physical change (c) corrosion and it is a chemical change (d) dissolution and it is a chemical change

Answer:

  (c) Rusting of an article made up of iron is called corrosion. Corrosion is a chemical change because rust is a chemical compound (hydrated iron oxide, which is totally different from element iron (Fe). Corrosion is Physical changes are those changes in which no new substances are formed. The substances do not change their identity and they can be easily returned to their original form by some physical processes, e.g., melting of ice, glowing of an electric bulb, breaking of glass tumbler, etc. On the other hand, chemical changes are those changes in which new substances are formed. The substances involved change their identity and they get converted into entirely new substances, which cannot be returned to their original form. e.g., burning of paper, rusting of iron, burning of magnesium wire, etc.