Question detail
Which statement would earn credit for Use Rf values to compare and identify substances.?
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. The distance moved by the solvent
- B. The distance moved by the substance
- C. The ratio of the distance moved by the substance to the distance moved by the solvent
- D. The total distance moved by all substances
Answer
The correct answer is The ratio of the distance moved by the substance to the distance moved by the solvent. It matches chromatography because the evidence is spot and solvent-front distances and the expected result is Rf or separation evidence.
Explanation
The correct option is The ratio of the distance moved by the substance to the distance moved by the solvent. 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
Misunderstanding Rf Values
Students often confuse Rf values with absolute measurements, thinking they represent the actual distance a substance travels rather than a ratio.
Emphasize that Rf values are calculated as the distance moved by the substance divided by the distance moved by the solvent, and they are dimensionless ratios used for comparison.
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