Explain why burning of wood and cutting it into small piece are considered as two different types of changes.
When we burn wood, a new substance, coal, is formed. Therefore, it is a chemical change. However, 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.
Burning of wood is a chemical change because in burning new substances are formed as
Wood + Oxygen ———–> Charcoal + Carbon dioxide + Heat + Light
But cutting it into small pieces is physical change because no new substance is formed. We can only reduce the size of wood