To find out what gas is in each of the test tubes, it is enough to place a burning chip or match in each of them. In a test tube with carbon dioxide, the match will immediately go out. With oxygen, on the contrary, it will flare up with a bright strong flame. In a test tube with hydrogen, we will hear a pop, as if pulling a cork from a bottle (hydrogen burning with an explosion). A test tube with air remains. In it, a burning match will gradually go out as the oxygen burns out.
One of the components of a person's success in our time is receiving modern high-quality education, mastering the knowledge, skills and abilities necessary for life in society. A person today needs to study almost all his life, mastering everything new and new, acquiring the necessary professional qualities.