State four characteristics of gas.

1. They do not have a definite shape and volume: The molecules of gases are loosely packed.

2. Gases can flow: They can move easily and also exhibits negligible force of attraction which doesn't allow the molecules to remain in their place.

3. Gases are compressible: The molecules are far away from each other. So, the Intermolecular spaces are maximum so they are compressible.

4. The rate is diffusion is higher than in solids and liquids because of the higher kinetic energy.