Burning of wood and cutting it into small pieces are considered two different types of changes because they involve fundamentally different processes:
- Burning of Wood is a chemical change :
- When wood burns, it reacts with oxygen in the air and forms new substances like carbon dioxide, water vapor, ash, and smoke.
- The chemical composition of the wood changes.
- This process is irreversible — the original wood cannot be recovered once burnt.
- Energy in the form of heat and light is released during burning.
- Cutting Wood into Small Pieces is a physical change :
- Cutting changes only the shape and size of the wood but does not alter its chemical composition.
- No new substances are formed.
- It is a reversible process in principle, as the wood pieces remain chemically the same as the original wood.
In summary, burning wood alters its chemical identity producing new substances, while cutting wood changes only its physical form without changing its chemical nature, making burning a chemical change and cutting a physical change.
