CAIE A Level Chemistry 9701 · States of matter
Helium gas is stored under pressure in a sealed metal cylinder. A student suggests that the pressure on the inside walls of the cylinder is caused by the helium atoms repelling one another and pushing the walls outward.
Suggest why this suggestion is incorrect. In your answer, explain how the pressure is actually produced and state the two assumptions made about the particles in the ideal gas model.
5 marks, so the mark scheme is looking for about 5 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.
Written by Markquill to follow the Cambridge International syllabus. Markquill is independent and is not affiliated with or endorsed by Cambridge International.