Long answer·Hard exam skill (4/5)·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 laboratory model uses a membrane that allows water to pass but not starch molecules. Starch solution is placed inside the membrane bag and the bag is kept in water.
Total: 4 marks
(a) What type of membrane is being modelled in this experiment? (1 mark)
(b) In which direction will water move initially, and why? (2 marks)
(c) What will happen to the volume inside the bag after some time? (1 mark)
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