Question detail
In Pure substances, which answer best matches the 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. They increase the boiling point.
- B. They decrease the boiling point.
- C. They do not affect the boiling point.
- D. They make the boiling point unpredictable.
Answer
The correct answer is They increase the boiling 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 They increase the boiling point.. This is correct because single element or compound / fixed melting point is the evidence expected for pure substance, and purity evidence is the result that supports the conclusion. 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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