MCQOPTIONS
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MCQOPTIONS
This section includes 27 Mcqs, each offering curated multiple-choice questions to sharpen your Biochemistry knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
What does the retention factor, , describe? |
| A. | The distribution of an analyte between the stationary and the mobile phase |
| B. | The migration rate of an analyte through a column |
| C. | The velocity of the mobile phase |
| D. | All of these |
| Answer» C. The velocity of the mobile phase | |
| 2. |
Which of the following is not used for detection in GC? |
| A. | Infrared spectroscopy |
| B. | NMR |
| C. | Flame ionisation |
| D. | Electrical conductivity |
| Answer» C. Flame ionisation | |
| 3. |
Which of these effects result from slow injection of a large sample volume? |
| A. | Increased resolution |
| B. | Decreased resolution |
| C. | Non-linear detector response |
| D. | Constant resolution |
| Answer» C. Non-linear detector response | |
| 4. |
The GC trace obtained after an experiment is called a |
| A. | chromatograph |
| B. | chromatogram |
| C. | chromatophore |
| D. | graph |
| Answer» C. chromatophore | |
| 5. |
Which of the following detectors give concentration-dependent signals? |
| A. | Electron-capture detector |
| B. | Thermal conductivity |
| C. | Infra-red detector |
| D. | All of these |
| Answer» E. | |
| 6. |
Sample retention in the column is measured by |
| A. | retention time |
| B. | retention factor |
| C. | retention index |
| D. | all of these |
| Answer» E. | |
| 7. |
Column bleeding occurs when |
| A. | elution of the analyte is extended over time |
| B. | the column is cracked and stationary phase leaks out |
| C. | traces of the stationary phase are eluted |
| D. | the column breaks during installation and causes personal injury |
| Answer» D. the column breaks during installation and causes personal injury | |
| 8. |
Which of the following gases is unsuitable for use as a GC carrier gas? |
| A. | Nitrogen |
| B. | Helium |
| C. | Oxygen |
| D. | All of the above |
| Answer» D. All of the above | |
| 9. |
Which of the following are not used as stationary phases in a GC column? |
| A. | Polysiloxanes |
| B. | Silica |
| C. | Cyclodextrins |
| D. | None are used as stationary phases |
| Answer» C. Cyclodextrins | |
| 10. |
Doubling the column's length increases resolution by a factor of |
| A. | (2) |
| B. | <sup>0.5</sup> |
| C. | 2 |
| D. | 3 |
| E. | 4 |
| Answer» B. <sup>0.5</sup> | |
| 11. |
Sample injection is considered successful if |
| A. | all of the sample in the injector has been added to the column |
| B. | the sample is concentrated at the start of the column |
| C. | the sample is spread evenly along the column |
| D. | the sample is homogenously spread along the column |
| Answer» C. the sample is spread evenly along the column | |
| 12. |
A retention gap is placed between the injector and the front of the column to |
| 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 |
| Answer» B. retain the sample and release it gradually to the column | |
| 13. |
Which of the following detectors give mass flow-dependent signals? |
| A. | Electron capture detector |
| B. | Field ionisation detector |
| C. | Thermal conductivity detector |
| D. | All of the above |
| Answer» C. Thermal conductivity detector | |
| 14. |
Theoretical plates are used to |
| 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 |
| Answer» B. determine the thickness of the stationary phase | |
| 15. |
What does the selectivity factor describe? |
| A. | The proportional difference in widths of two chromatographic peaks |
| B. | The maximum number of different species which a column can separate simultaneously |
| C. | The relative separation achieved between two species |
| D. | None of the above |
| Answer» D. None of the above | |
| 16. |
Helium is generally preferred as carrier gas over nitrogen and hydrogen because |
| A. | it is inert |
| B. | it has a lower viscosity |
| C. | it doubles up as a party gas for balloons and funny voices |
| D. | all of above |
| Answer» E. | |
| 17. |
What is the typical internal diameter of fused silica capillary columns? |
| A. | 0.2-0.3 mm |
| B. | 0.3-0.5mm |
| C. | 0.5-1.0 mm |
| D. | 1.0-2.0 mm |
| Answer» B. 0.3-0.5mm | |
| 18. |
Resolution is proportional to the |
| A. | number of theoretical plates in a column |
| B. | square root of the number of theoretical plates in a column |
| C. | square of the number of theoretical plates in a column |
| D. | cube root of the number of theoretical plates in a column |
| Answer» C. square of the number of theoretical plates in a column | |
| 19. |
Derivatisation of a sample is carried out to |
| A. | reduce polarity of the analytes |
| B. | increase the detector response |
| C. | increase volatility of the analytes |
| D. | all of the above |
| Answer» E. | |
| 20. |
Which of the statements is correct? |
| A. | Gas chromatography is used to analyse gases |
| B. | Gas chromatography is used to analyse solids |
| C. | Gas chromatography is used to analyse gases, solutions and solids |
| D. | All of the above |
| Answer» E. | |
| 21. |
In column switching chromatography |
| A. | compounds trapped on one column are eluted to another column |
| B. | one column is removed and replaced by another |
| C. | the flow to the column is switched on and off repeatedly |
| D. | any of the above |
| Answer» B. one column is removed and replaced by another | |
| 22. |
The column is heated to |
| A. | prevent analyte condensation within the column |
| B. | control elution of the different analytes |
| C. | reduce band broadening to get sharper peaks |
| D. | all of these |
| Answer» E. | |
| 23. |
What are the benefits of decreasing the column internal diameter? |
| A. | Increased sample capacity |
| B. | Increased resolution |
| C. | Reduced risk of column overloading |
| D. | All of the above |
| Answer» C. Reduced risk of column overloading | |
| 24. |
Headspace analysis is carried out in order to |
| 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 |
| Answer» B. determine the psychological state of the tutor | |
| 25. |
Split injection is carried out by |
| 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 |
| Answer» D. none of the above | |
| 26. |
What does the retention factor, k', describe? |
| A. | The distribution of an analyte between the stationary and the mobile phase |
| B. | The migration rate of an analyte through a column |
| C. | The velocity of the mobile phase |
| D. | All of these |
| Answer» C. The velocity of the mobile phase | |
| 27. |
What useful information can be found from a Van Deemter plot? |
| A. | The selectivity factor |
| B. | Optimum mobile phase flow rate |
| C. | Optimum column temperature |
| D. | Optimum column length |
| Answer» C. Optimum column temperature | |