Question detail
Which answer avoids confusing pure substance with another qualitative analysis result?
Try the question, check the answer, then read the explanation to understand the curriculum point.
At a glance
MCQ
Type
practice
Style
Topic
Purity, formulations and chromatography
Question
- A. It is a pure substance
- B. It is an impure substance
- C. It is a solid
- D. It is a gas
Answer
The correct answer is It is an impure substance. It matches pure substance because the evidence is single element or compound / fixed melting point and the expected result is purity evidence.
Explanation
The correct option is It is an impure substance. Use this as an exam check: if the observation is not purity evidence, the conclusion about pure substance is not properly supported. Other options are weaker when they confuse gas tests, flame colours, ion-test precipitates, chromatography evidence, or pure-substance/formulation wording.
Common mistake
Confusing Boiling Points
Students often think that a substance can be identified as pure if it boils at any temperature within a range.
Remind students that a pure substance has a specific boiling point, and deviations from this indicate impurities.
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