Question 1Multiple choice · 1 markA* challenge
What is the lowest possible temperature?
- A −273 °C
- B 0 °F
- C −100 °C
- D 0 °C
Show answer
Answer: A
Free Kinetic particle model questions for IGCSE Physics (0625), part of Thermal physics. Each question has the answer and the marking points an examiner would look for.
Generate a full Kinetic Particle Model worksheet →All Thermal physics questionsWhat is the lowest possible temperature?
Answer: A
Which change happens when the temperature of a gas rises?
Answer: C
Evaporation and boiling both change a liquid into a gas.
Explain, using the particle model, why evaporation cools a liquid.
State two ways in which evaporation differs from boiling.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | most energetic escape the most energetic particles escape from the surface B1 the particles left behind have a lower average kinetic energy B1 so the temperature of the liquid falls B1 | 3 |
| (b) | any temperature; surface only evaporation happens at any temperature (boiling only at the boiling point) B1 evaporation only at the surface (boiling throughout the liquid) B1 | 2 |
This question is about the kinetic particle model of matter.
Smoke particles in air are viewed through a microscope. Describe their motion.
Explain why the air molecules themselves cannot be seen but their effect can.
Describe the relationship between the temperature of a gas and the motion of its particles.
State what is meant by absolute zero and give its value in °C.
Explain, using the particle model, why a sealed container of gas exerts a pressure on its walls.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | random, jerky, zig-zag motion random B1 jerky / zig-zag movement in all directions B1 | 2 |
| (b) | air molecules too small; smoke particles large enough to see, moved by many collisions air molecules are too small to be seen B1 the larger smoke particles are visible and their motion shows the effect of the collisions B1 | 2 |
| (c) | higher temperature, higher average kinetic energy / speed higher temperature means a higher average kinetic energy B1 so the particles move faster on average B1 | 2 |
| (d) | lowest possible temperature; −273 °C the lowest possible temperature (particles have least kinetic energy) B1 −273 °C B1 | 2 |
| (e) | particles collide with walls; force over area gas particles collide with the walls B1 each collision exerts a force, and force per unit area is pressure B1 | 2 |
Smoke particles in air are viewed through a microscope. The smoke particles are seen to move in a random, jerky way.
State the name of this motion.
Explain what causes the motion.
State what this shows about air molecules.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | Brownian motion Brownian motion B1 | 1 |
| (b) | collisions with air molecules the smoke particles are hit by (invisible) air molecules B1 the air molecules move randomly at high speed B1 collisions are uneven, so the smoke particle moves in random directions B1 | 3 |
| (c) | they are small and move fast air molecules are very small and move rapidly and randomly B1 | 1 |
Explain, in terms of particles, why a solid has a fixed shape and a liquid does not.
Solid.
Liquid.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | fixed positions, strong forces particles are held in fixed positions B1 by strong forces between them B1 | 2 |
| (b) | particles can slide past each other particles are close together but can move/slide past each other B1 forces are weaker B1 | 2 |
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