* Sulfur dioxide (SO2) is formed: When sulfur burns, it reacts with oxygen in the air to produce sulfur dioxide (SO2).

* Sulfur dioxide is acidic: Sulfur dioxide is a gas that dissolves in water to form sulfurous acid (H2SO3), which is acidic.

* Alkaline substances have a pH greater than 7: Alkaline substances, also known as bases, have a pH greater than 7.

Therefore, sulfur dioxide is not an alkaline gas; it is an acidic gas.