Gas Chromatography problems
- 1. Which of the following gases is unsuitable for use as a GC carrier gas?
Options- A. Nitrogen
- B. Helium
- C. Oxygen
- D. All of the above Discuss
Correct Answer: Oxygen
- 2. Which of the following are not used as stationary phases in a GC column?
Options- A. Polysiloxanes
- B. Silica
- C. Cyclodextrins
- D. None are used as stationary phases Discuss
Correct Answer: Silica
- 3. Which of the following detectors give concentration-dependent signals?
Options- A. Electron-capture detector
- B. Thermal conductivity
- C. Infra-red detector
- D. All of these Discuss
Correct Answer: All of these
- 4. Headspace analysis is carried out in order to
Options- A. analyse volatile compounds from solid or liquid samples
- B. determine the psychological state of the tutor
- C. analyse the column contents ahead of the sample
- D. determine non-volatiles Discuss
Correct Answer: analyse volatile compounds from solid or liquid samples
- 5. Theoretical plates are used to
Options- A. estimate the efficiency of a column
- B. determine the thickness of the stationary phase
- C. measure the distribution of the analyte between mobile and stationary phases
- D. None of the above Discuss
Correct Answer: estimate the efficiency of a column
- 6. What is the typical internal diameter of fused silica capillary columns?
Options- A. 0.2-0.3 mm
- B. 0.3-0.5mm
- C. 0.5-1.0 mm
- D. 1.0-2.0 mm Discuss
Correct Answer: 0.2-0.3 mm
- 7. A retention gap is placed between the injector and the front of the column to
Options- A. retain contaminants and prevent them from reaching the column
- B. retain the sample and release it gradually to the column
- C. prevent backflush of the injected solution
- D. all of the above Discuss
Correct Answer: retain contaminants and prevent them from reaching the column
- 8. Split injection is carried out by
Options- A. splitting the sample into smaller portions to inject sequentially
- B. splitting the sample into smaller portions to inject at the same time through parallel ports
- C. splitting off some of the sample so that it does not enter the column
- D. none of the above Discuss
Correct Answer: splitting off some of the sample so that it does not enter the column
- 9. What useful information can be found from a Van Deemter plot?
Options- A. The selectivity factor
- B. Optimum mobile phase flow rate
- C. Optimum column temperature
- D. Optimum column length Discuss
Correct Answer: Optimum mobile phase flow rate
- 10. The GC trace obtained after an experiment is called a
Options- A. chromatograph
- B. chromatogram
- C. chromatophore
- D. graph Discuss
Correct Answer: chromatogram
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