Question detail
A chromatogram shows a substance with a distance travelled by the substance of 5 cm and a distance travelled by the solvent front of 10 cm. What is the Rf value?
Try the question, check the answer, then read the explanation to understand the curriculum point.
At a glance
MCQ
Type
practice
Style
Topic
Chromatography (A-level only)
Question
- A. 0.5
- B. 1.0
- C. 2.0
- D. 0.25
Answer
0.5
Explanation
The correct option is 0.5. 0.5 is the best answer because it directly supports the AQA A-Level Chemistry objective to calculate and interpret Rf values. This reasoning is anchored to Chromatography (A-level only) in Chromatography (A-level only), and it separates Rf value from similar A-Level ideas rather than relying on a vague recall statement. Other options are weaker if they use the wrong evidence, calculation, mechanism, observation, unit, or conclusion for this subtopic.
Common mistake
Incorrect Rf Value Calculation
Students often forget to measure the distance travelled by the substance from the baseline when calculating the Rf value.
Always measure the distance from the baseline to the centre of the spot for the substance and divide it by the distance travelled by the solvent front.
Related flashcards
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