Topic 2.1: Kinetic Particle Model of Matter

Descriptions of two different states of matter are shown below. To which state of matter do each of the descriptions fit?

X: the molecules are very close together, in fixed positions. They vibrate around these fixed positions.

Y: the molecules move rapidly and randomly in straight lines until they collide with something. The molecules are spaced apart very far.

• A

• B

• C

• D

The diagrams represent the molecules in two different states of matter. The arrows show the motion of the molecules. Which state represents a solid?

• state 1

• neither

• both

• state 2

Air is trapped inside a cylinder. The volume of the cylinder cannot change. The temperature of the air is increased. Which of the graphs below shows the correct relationship between pressure and temperature?

• A

• B

• C

• D

A beaker of water, at its boiling point of 100 C, is heated so that the liquid starts to become a gas, also at 100 C. Which row of the table correctly compares the liquid phase with the gas phase under these conditions?

• As

• B

• C

• D

A sealed yet empty (except for air) plastic drinks bottle is left outside in the sunshine on a warm day. Which row of the table correctly describes what happens to the average speed of the air molecules, and to the pressure inside the bottle?

• A

• B

• C

• D

A car tyre is inflated with air. As the car drives, the temperature of the tyre increases, which also causes the temperature of the air inside the tyre to increase. This increases the pressure of the air inside the tyre. Which of the following is a correct explanation as to why?

• The mass of air inside the tyre has increased.

• The area of the tyre has decreased, thus increasing the pressure.

• The air molecules collide with each other less frequently.

• The average kinetic energy of the air molecules has increased.

A sealed piston is used to expand a gas. No gas escapes during the process. What happens to both the density of the gas and to its pressure when it is expanded in this way?

• 
• 
• 
• 

A sealed gas syringe contains a fixed mass of gas. The piston is moved and the volume of the gas doubles. The temperature of the gas does not change. What happens to the pressure of the gas?

• halves

• no change

• doubles

• triples

A gas is in a sealed container of constant volume. The gas is heated and the pressure of the gas on the walls of the container increases. How do the particles of the gas cause this increase in pressure?

• They expand.

• They hit each other more frequently.

• They hit the container walls more frequently.

• They vibrate faster

A whale takes a breath at the surface of the ocean, where the pressure is 1.00 × 10 Pa. It then dives to a depth where the pressure is 1.21 × 10 Pa. The temperature is the same at this depth as it is at the surface. The whale lets out a bubble of air of volume 50 cm. This bubble rises to the surface of the ocean. What is the volume of the bubble when it reaches the surface?

• 41.3 cm

• 60.5 cm

• 50.0 cm

• 21.0 cm