Question detail
In the saffron written-response scenario for Chromatography, explain how Rf value supports this objective: 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
Question
Type
exam_style
Style
Topic
Purity, formulations and chromatography
Question
In the saffron written-response scenario for Chromatography, explain how Rf value supports this objective: Use Rf values to compare and identify substances..
Answer
A high-scoring answer should explain use Rf values to compare and identify substances. Use evidence before identification: name the relevant test or measurement, state the observation, and then connect the result to Chromatography.
Explanation
The important distinction is that chromatography must be identified from spot and solvent-front distances; answers that swap in a different test or result do not match Chromatography. A complete answer should use the approved objective wording, include the relevant evidence, and avoid unsupported identification claims.
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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