Here's why:

* Chemical properties describe how a substance reacts with other substances or how it changes its chemical composition. Burning is a chemical reaction where the substance combines with oxygen, releasing energy in the form of heat and light.

* Physical properties describe the characteristics of a substance that can be observed without changing its chemical composition. Examples include color, texture, density, melting point, and boiling point.

Since burning involves a chemical change in the substance, it's classified as a chemical property.