Classify the changes involved in the following processes as physical or chemical changes:

  1. Photosynthesis
  2. Dissolving sugar in water
  3. Burning of coal
  4. Melting of wax
  5. Beating aluminium to make aluminium foil
  6. Digestion of food


(a) It results in the production of new substances (such as food for plants and CO2 ).

  • Hence, Photosynthesis is a chemical change.

(b) It is a temporary change, and sugar crystals can be obtained back from water through heating.

  • Hence, dissolving sugar in water is a physical change

(c) Burning is always accompanied by the evolution of heat and ligh t and is irreversible .

  • Hence, burning of coal is a chemical change

(d) Melting of wax leads to a change in the state of wax and is reversible .

  • Hence, melting of wax is a physical change.

(e) Beating aluminium leads to a change in shape but leads to no changes in the properties of aluminium.

Therefore, beating aluminium to make aluminium foil is a physical change.

(f) Digestion of food involves chemical reactions , absorption and formation of new products in the digestive system. 

Therefore, digestion of food is a chemical change.

Go Ad-free
Maninder Singh's photo - Co-founder, Teachoo

Made by

Maninder Singh

CA Maninder Singh is a Chartered Accountant for the past 14 years and a teacher from the past 18 years. He teaches Science, Economics, Accounting and English at Teachoo