Long answer·Standard multi-step (3/5)·No calculator
Difficulty guide
The label describes the problem, not your ability.
1/5 - Foundational
Warm-up setup; checks one basic idea.
2/5 - Routine exam skill
Normal syllabus skill; usually one main rule or interpretation.
3/5 - Standard multi-step
Exam-style problem with multiple steps or a common trap.
4/5 - Hard exam skill
High-end exam problem; combines methods carefully.
5/5 - Challenge
Stretch problem beyond normal exam pressure.
Question
A rigid vessel contains an ideal gas at temperature . Half the molecules are slowly removed while the temperature and vessel volume are kept unchanged.
Total: 4 marks
(a) How does the number density change? (1 mark)
(b) How does the pressure change? (1 mark)
(c) How does rms speed change? (1 mark)
(d) How does mean free path change? Explain. (1 mark)
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