How can you test for the presence of oxygen gas?

To confirm the presence of oxygen gas, inserting a glowing splint into a test tube containing the gas leads to the relighting of the splint. This procedure exploits oxygen's role in combustion processes, as it is a key reactant in most fire reactions. When the glowing splint is introduced into oxygen, the increased concentration of the gas enables it to support combustion more effectively than air alone, resulting in the splint reigniting. This distinctive reaction serves as a reliable test for detecting oxygen, demonstrating its chemical properties.