Q.List the characteristic physical properties of the gases.

Step 1. Density: gases are far lighter than solids or liquids, i.e. they have much lower density.

Step 2. Shape and volume: gases have no fixed shape or volume of their own; they occupy the entire space available and take the shape of whatever container holds them.

Step 3. Molecular motion and pressure: gas molecules are widely separated and in continuous, random motion, colliding constantly with each other and the container walls; it is this collision with the walls that produces gas pressure, exerted equally in every direction.

Step 4. Intermolecular forces: these are the weakest of the three states of matter in a gas.

Step 5. Diffusion: gases spontaneously and uniformly intermix with one another, a property called diffusion.

Step 6. Compressibility: because gas molecules occupy only a tiny fraction of the total volume available, gases are highly compressible.

List each of the six characteristic physical properties of gases.

• Omitting the connection between random molecular motion/wall collisions and the origin of gas pressure.
• Forgetting compressibility or diffusion as distinct characteristic properties.