Question detail
A student is testing chromatography. Which choice keeps the observation and conclusion correctly linked?
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. field kit sampling-error: spot distance divided by solvent-front distance
- B. field kit reject: a method from a different Chemical analysis subtopic is used
- C. field kit reject: the conclusion is stated before any observation is given
- D. field kit reject: the answer measures quantity rather than identifying the substance
Answer
The correct answer is field kit sampling-error: spot distance divided by solvent-front distance. 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 field kit sampling-error: spot distance divided by solvent-front distance. 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. 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 Value Calculation
Students often confuse the distances moved by the substance and the solvent when calculating Rf values.
Ensure to measure the distance moved by the substance and the distance moved by the solvent separately, then use the formula Rf = distance moved by substance / distance moved by solvent.
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