Chromatography Quiz
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5 questions, one answer each
Each answer is checked as you go, with why.
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1. A spot moves 2.4 cm while the solvent front moves 6.0 cm. What is its Rf value?
- A. 0.25
- B. 0.40
- C. 0.60
- D. 2.5
2. Which statement about the mobile phase in gas chromatography is correct?
- A. It is a liquid solvent
- B. It is a solid
- C. It is a volatile liquid sample
- D. It is an inert gas
3. Why is HPLC preferred to GC for a non-volatile drug that decomposes on heating?
- A. The sample does not have to be vaporised
- B. HPLC does not need a stationary phase
- C. HPLC has no retention times
- D. HPLC is always faster
4. Two compounds have different retention times in HPLC. What does this show?
- A. They have the same relative molecular mass
- B. They are present in different amounts
- C. They interact differently with the stationary and mobile phases
- D. They are both volatile
5. Why is a mass spectrometer connected to a chromatography column?
- A. To make the separation faster
- B. To identify each component from its molecular mass and fragmentation
- C. To heat the sample
- D. To measure Rf values