Chemical change is the burning of wood and cutting of wood is a physical change. The burning of wood produces ash and smoke that means two new substances are formed. Wood (cellulose ) changes into ash , carbon dioxide and water . Hence the properties of wood are changed. So, it’s a chemical change. When a log of wood ( chemically cellulose ) is cut into small pieces ( chemically cellulose ), So it is a physical change. Each small piece bears the properties of wood and there’s no new substance formed.