CIE IGCSE Physics

Topic Questions

IGCSEPhysicsCIETopic Questions2. Thermal Physics2.1 Kinetic Particle Model of Matter

2.1 Kinetic Particle Model of Matter

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11 mark

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.

q1-easy-mcq-2-1-simple-kinetic-cie-igcse-physics

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.

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21 mark

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.

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31 mark

A sealed piston is used to expand a gas. No gas escapes during the process.

q3-easy-mcq-2-1-simple-kinetic-cie-igcse-physics

What happens to both the density of the gas and to its pressure when it is expanded in this way?

 

Density

Pressure

A

stays the same

stays the same

B

increases

decreases

C

decreases

stays the same

D

decreases

decreases

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41 mark

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.

   

 

State X

State Y

A

solid

liquid

B

solid

gas

C

liquid

gas

D

gas

liquid

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51 mark

The diagrams represent the molecules in two different states of matter. The arrows show the motion of the molecules.

2-1-5-e-molecules-states-of-matter

Which state represents a solid?

  • state 1

  • neither

  • both

  • state 2

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11 mark

A whale takes a breath at the surface of the ocean, where the pressure is 1.00 x 105 Pa. It then dives to a depth where the pressure is 1.21 x 105 Pa. The temperature is the same at this depth as it is at the surface.

q1-hard-mcq-2-1-simple-kinetic-cie-igcse-physics

The whale lets out a bubble of air of volume 50 cm3. This bubble rises to the surface of the ocean.

What is the volume of the bubble when it reaches the surface?

  • 41.3 cm3

  • 60.5 cm3

  • 50.0 cm3

  • 21.0 cm3

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21 mark

The water in outdoor swimming pools gradually evaporates.

How does the process of evaporation affect the temperature of the water in the swimming pool and what is the effect on the average kinetic energy of the water molecules?

 

Temperature

Average kinetic energy per molecule

A

reduces

reduces

B

stays the same

stays the same

C

increases

increases

D

reduces

stays the same

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31 mark

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?

 

Temperature

Wind speed

A

warm

windy

B

warm

still

C

cool

windy

D

cool

still

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41 mark

In an experiment to determine the nature of liquids, some very tiny pollen grains are suspended in water. They are illuminated by a bright light, and observed under a microscope.

q4-hard-mcq-2-1-simple-kinetic-cie-igcse-physics

The view through the microscope is of small, bright dots, which move about at random, rapidly and they frequently change direction.

Which of the following would be the correct explanation for the observation through the microscope?

  • The bright dots are water molecules, being hit by other water molecules.

  • The bright dots are water molecules, which are vibrating due to their thermal kinetic energy.

  • The bright dots are pollen grains, which are being hit many times per second by water molecules.

  • The bright dots are pollen grains, which are vibrating due to their thermal kinetic energy.

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51 mark

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?

 

Pressure inside syringe

Speed of air molecules

A

stays the same

stays the same

B

increases

decreases

C

decreases

stays the same

D

decreases

decreases

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11 mark

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

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

q1-medium-mcq-2-1-simple-kinetic-cie-igcse-physics

  • Molecule A

  • Molecule B

  • Molecule C

  • Molecule D

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21 mark

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?

q2-medium-mcq-2-1-simple-kinetic-cie-igcse-physics

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31 mark

A beaker of water, at its boiling point of 100 oC, is heated so that the liquid starts to become a gas, also at 100 oC.

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

 

Average distance between the particles

Average speed of the particles

A

the same in the liquid and the gas

the same in the liquid and the gas

B

greater in the liquid

greater in the gas

C

greater in the gas

greater in the liquid

D

greater in the gas

the same in the liquid and the gas

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41 mark

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?

 

Average speed of particles

Pressure inside bottle

A

increases

increases

B

increases

decreases

C

decreases

increases

D

decreases

decreases

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51 mark

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.

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