CAIE A Level Chemistry 9701 · States of matter
A gas cylinder contains helium.
(a) Suggest how the helium exerts pressure on the inside walls of the cylinder.
(b) The ideal gas model assumes that gas particles have zero volume and that there are no forces between them.
Suggest why each assumption becomes unrealistic when the helium is compressed to a very high pressure.
4 marks, so the mark scheme is looking for about 4 separate creditworthy points. Making the same point twice in different words earns it once.
Suggest means: Apply what you know to an unfamiliar situation. There may be more than one acceptable answer. Reason from the principle you have learned to the new context, and say which principle you are using.
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