Question detail
Which statement would earn credit for Interpret melting point or boiling point data to decide whether a substance is pure or…?
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 melts and boils over a range of temperatures.
- B. It melts and boils at specific temperatures.
- C. It has no defined melting or boiling point.
- D. It can be a mixture of different substances.
Answer
The correct answer is It melts and boils at specific temperatures.. 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 melts and boils at specific temperatures.. The answer stays inside Purity, formulations and chromatography by linking the observation to the conclusion instead of naming a substance without evidence. 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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