What this practice covers
These questions are drawn from past CIE 9702 Physics papers and filtered to thermodynamics. You answer, you find out immediately whether you were right, and you get the reasoning for the correct option and for each distractor. Wrong answers go to a mistakes locker so you can come back to exactly those.
Practice is free. You need an account only so your progress and your mistakes are still there next time.
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What examiners see students get wrong here
These are the errors that cost marks on thermodynamics, taken from our own topic notes. Read them before you practise and you will recognise the traps in the questions.
- Substituting W = +pΔV into the first law after an expansion, instead of W = -pΔV.
- Saying internal energy is the total kinetic energy of the molecules, and leaving out the potential term.
- Including the kinetic energy of the whole object moving, or its gravitational potential energy, in the internal energy.
- Saying that internal energy depends on how the system got to its state. It depends only on the state.
- Saying an ideal gas has potential energy between its molecules. The model assumes there are no intermolecular forces except during collisions.
- Saying the temperature must rise whenever internal energy rises. During melting or boiling it does not.
- Leaving the volume in cm³ in W = pΔV, so the answer is out by a factor of a million.
- Applying W = pΔV where the pressure is not constant.
Revise it first
If any of the above is unfamiliar, work through the notes before practising: Thermodynamics revision notes.