Question detail
A student is testing pure substance. Which choice keeps the observation and conclusion correctly linked?
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 likely a pure substance.
- B. It is likely a mixture.
- C. It is likely a solid.
- D. It is likely a gas.
Answer
The correct answer is It is likely a mixture.. 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 likely a mixture.. The important distinction is that pure substance must be identified from single element or compound / fixed melting point; answers that swap in a different test or result do not match Pure substances. Other options are weaker when they confuse gas tests, flame colours, ion-test precipitates, chromatography evidence, or pure-substance/formulation wording.
Common mistake
Identifying Purity from Melting Points
Students often think that a substance is pure if it has a melting point that matches the literature value, without considering the possibility of impurities affecting the melting point.
Students should remember that impurities can lower or raise the melting point, and they should analyze the melting point range to determine purity.
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