Case study·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 student compares the acidity of three fruit juices. Equal volumes of each juice are diluted with the same volume of distilled water, the same number of universal-indicator drops is added, and colours are matched after the same time.
Total: 3 marks
(a) Why should equal volumes of juices be used? (1 mark)
(b) Why should the same number of indicator drops be used? (1 mark)
(c) Why should colour matching be done after the same time? (1 mark)
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