5. Give a few examples of chemical changes?

Answer 1

1. Digestion of food in human body
2. Burning of wood or coal
3. Rusting of iron
4. Cooking food
5. Baking a cake
6. Fermentation of grapes to make wine
7. Burning of gasoline in an engine
8. Photosynthesis in plants
9. Decomposition of organic matter
10. Electrolysis of water.

Answer 2

Do you think a chemical and a physical change can happen at the same time? Why or why not?

Answer 3

Yes, a chemical and a physical change can happen at the same time. This is because during certain reactions, the substance undergoing change may experience both a chemical and physical change simultaneously. For example, when water freezes, a physical change occurs as its state changes from liquid to solid, but a chemical change also occurs as the individual water molecules arrange themselves into a crystalline structure with new physical and chemical properties. The occurrence of both changes simultaneously is not mutually exclusive and can happen together in some reactions.