What are five properties of gases?
Too long for one sentence, see the Explanation.
They have low density.
They occupy the whole volume of what they are put into.
They contract and heat up under pressure (think of how hot a bicycle tire feels when you have pumped air into it).
They can also condense to liquids or solids under pressure (like pressurized propane tanks for grills), or when cooled (like stored liquid nitrogen for some lab equipment).
They form rising bubbles when formed in a liquid that undergoes a chemical reaction (like the carbon dioxide formed when limestone is dropped into an acid).