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.

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At a glance

MCQ

Type

practice

Style

Topic

Purity, formulations and chromatography

Question

A. It remains the same
B. It increases
C. It decreases
D. It becomes unpredictable

Answer

The correct answer is It becomes unpredictable. 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 becomes unpredictable. 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

Misunderstanding Melting and Boiling Points

Students often think that all substances melt and boil at the same temperature regardless of purity.

Remember that a pure element or compound has specific melting and boiling points, while impurities can alter these temperatures.

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