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 salt solution is tested. With dilute acid it gives no effervescence. With barium chloride it gives a white precipitate that remains after adding dilute hydrochloric acid. With sodium hydroxide it gives no pungent gas on warming.
Total: 3 marks
(a) Which anion is indicated? (1 mark)
(b) Which common anion is ruled out by no effervescence with dilute acid? (1 mark)
(c) Which cation is ruled out by no pungent gas with sodium hydroxide? (1 mark)
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