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 teacher gives three food samples. Sample P gives blue-black colour with iodine. Sample Q gives violet colour with biuret reagent. Sample R reduces Fehling's solution on heating.
Total: 4 marks
(a) Identify the main component indicated in P. (1 mark)
(b) Identify the main component indicated in Q. (1 mark)
(c) What type of carbohydrate is indicated in R? (1 mark)
(d) Why should separate portions of the sample be used for different tests? (1 mark)
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