Question detail
For Purity, formulations and chromatography, which option uses the correct Chemical analysis evidence for pure substance?
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 boils at a range of temperatures
- B. It boils at a specific temperature
- C. It has a lower boiling point than expected
- D. It boils and then freezes
Answer
The correct answer is It boils at a specific temperature. 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 boils at a specific temperature. This response is stronger than the distractors because it keeps the test, observation, and interpretation in the correct order for pure substance. 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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