Concept: Physical Change Chemical Change A temporary change. A permanent change. Affects only the physical properties that are size, shape, etc. It affects both physical and chemical properties as well as the composition. Despite the fact that a substance's molecules are rearranged when it experiences a physical change, its composition remains the same. A substance's molecular composition is completely altered when it experiences a chemical transformation. As a result, chemical transformations result in the production of new substances. No new substance is formed. A new substance is formed. The physical change is reversible, meaning the original material can be regained. Chemical transformations are irreversible, which means that the original substance cannot be restored. Examples - Melting of ice, Melting of wax, Boiling of water, etc. Examples - Burning of candle, Burning of paper, burning of wood, etc. Explanation: The given changes are - a. its size decreases - Physical Change b. there is melting of the wax - Physical Change c. flame and soot can be seen - Chemical Change d. melted wax also solidifies - Physical change a, b and d are physical changes because no new substances are formed and there is no change in the chemical composition of the wax. ( Only physical properties are changed.) In c, a new substance can be seen which is the flame and there is a change in the chemical composition as well as the chemical properties. The correct answer to this question is - c is a chemical change and the rest are physical changes.