Explain why burning of wood and cutting it into small pieces are considered as two different types of changes.
- When we burn wood, new substances, coal and smoke , are formed.
- Further, burning of wood is irreversible , and the chemical composition of wood changes .
- Therefore, it is a chemical change .
- But, when we cut wood, only the shape and size of the wood are changed .
- No new substance is formed.
- Therefore, it is a physical change .