Describe simple experiment to prove that gases occupy space
Experiment:
$$A$$ - A glass beaker or bowl is half-filled with water.
$$B$$ - An empty glass tumbler [which of course contains air] is inverted a lowered inside it.
$$C$$ — On tilting the tumbler, the air is displaced and bubbles are seen coming out.
Conclusion: $$\text{Air or gases occupy space}$$.