* Production of a new substance: Sulfur burning in air reacts with oxygen to form sulfur dioxide (SO₂). This is a completely different substance with different properties than sulfur.

* Change in color: Sulfur is yellow, while sulfur dioxide is a colorless gas. This change in color is a visible sign of a new substance being formed.

* Release of heat and light: The burning of sulfur is an exothermic reaction, meaning it releases heat and light. This energy release is a characteristic of many chemical changes.

* Change in odor: Sulfur dioxide has a pungent, suffocating odor. This distinct odor is another indication that a new substance with different properties has been created.

In summary: The formation of sulfur dioxide, accompanied by a change in color, release of heat and light, and a distinctive odor, are all clear indications that a chemical change has occurred when sulfur burns.