(i) In the test tube 2, oil cuts the supply of air to nail due to which oxidation of nail is prevented and boiled water is free from gases. Hence, the nail in the test tube 2 is not rusted.
(ii) The nail in the test tube 1 is highly rusted because nail is in contact with water and air. The oxidation process is fast.
(iii) No change is observed in the test tube 3. Nail remains as it is because the calcium chloride absorbs moisture, making the air dry, thus preventing rusting of the nail.
