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. If it melts over a range of temperatures.
- B. If it has a specific melting point.
- C. If it does not melt at all.
- D. If it melts quickly.
Answer
The correct answer is If it has a specific melting point.. 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 If it has a specific melting point.. 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
Misunderstanding Pure Substances
Students often think that a pure substance can contain small amounts of impurities and still be considered pure.
A pure substance must be a single element or compound with no other substances mixed in.
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