Discussion
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- Question
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
- Correct Answer
- Silica
- 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
- 2. Why is it advantageous to record many FID signals from the same sample and then add them together?
Options- A. To ensure that all target nuclei in the sample have been excited
- B. To remove inaccuracies caused by fluctuations in the applied magnetic field
- C. To increase sensitivity
- D. None of the above Discuss
- 3. What is the name given to the relaxation process due to an interaction between an excited nucleus and the magnetic fields caused by nuclei in molecules moving around in the sample?
Options- A. Spin - lattice relaxation
- B. Spin - spin relaxation
- C. Spin - spin - spin relaxation
- D. None of these Discuss
- 4. An FT-IR instrument record a signal in the
Options- A. time domain
- B. frequency domain
- C. both (a) and (b)
- D. none of these Discuss
- 5. When radiation energy is absorbed by a spin 1/2 nucleus in a magnetic field, what happens?
Options- A. The processional frequency of the nucleus increases
- B. The nucleus spins faster
- C. The angle of precession flips so that the magnetic moment of the nucleus opposes the applied field
- D. none of the above Discuss
- 6. 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
- 7. 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
- 8. 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
- 9. 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
- 10. 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
Gas Chromatography problems
Search Results
Correct Answer: Oxygen
Correct Answer: To increase sensitivity
Correct Answer: Spin - lattice relaxation
Correct Answer: time domain
Correct Answer: The angle of precession flips so that the magnetic moment of the nucleus opposes the applied field
Correct Answer: All of these
Correct Answer: analyse volatile compounds from solid or liquid samples
Correct Answer: estimate the efficiency of a column
Correct Answer: 0.2-0.3 mm
Correct Answer: retain contaminants and prevent them from reaching the column
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