G12 Physics (S2M1)

Below are four statements about evaporation. One of them is correct.

Which statement is correct?

• Evaporation cannot occur if a liquid's temperature is too low.

• Evaporation happens equally, In all directions, from all parts of a liquid.

• Evaporation cannot occur if a liquid is very dense

• Evaporation causes the temperature of the evaporating liquid to decrease

A popular demonstration of kinetic theory is to view smoke particles through a microscope, while illuminating them with a bright light.

The diagram shows the view of the smoke particles through a microscope. they are moving about randomly.

What causes the motion of the smoke particles?

• The smoke particles are attracted to each other

• The smoke particles vibrate because they are warm.

• Smaller air particles are colliding with the smoke particles.

• The microscope is vibrating slightly, making the smoke particles appear to move.

In a children's experiment, a saucer of water is left outside to evaporate. Which row shows weather conditions that will each cause the rate of evaporation from the saucer to increase?

• A

• B

• C

• D

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

The diagram shows four water molecules in a swimming pool. it also shows how much energy molecule has.

Which of the water molecules is most likely to evaporate from the liquid?

• Molecule A

• Molecule B

• Molecule C

• Molecule D

A beaker of water, at its boiling point of 100⁰C, is heated so that the liquid starts to become a gas, also at 100⁰C.

Which row of the table correctly compares the liquid phase with the gas phase under these conditions.

• A

• 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 syringe is half filled with air and sealed. the plunger is then pulled outwards, causing the volume of the gas to increase.

This is done slowly, so that the expansion happens at a constant temperature.

What happens to the pressure of the gas, and to the speed of the air molecules?

• A

• B

• C

• D

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?

• density stays the same; pressure stays the same

• density increases ; pressure decreases

• density decreases; pressure stays the same

• density decreases; pressure decreases

A substance is cooled. The graph below shows how its temperature changes over time.

What is happening in the portion of the graph labelled XY?

• The gas is cooling.

• The liquid is freezing.

• The gas is condensing.

• The liquid is cooling.