Gas Chromatography MCQs : This section focuses on the "Gas Chromatography". These Multiple Choice Questions (MCQs) should be practiced to improve the Gas Chromatography skills required for various interviews (campus interview, walk-in interview, company interview), placement, entrance exam and other competitive examinations.
Question 1
Which of the following is not an ideal characteristic of a detector used in gas chromatography?
A. Linear response to the solutes
B. Short response time
C. High reliability
D. Sensitive to the changes in the flow rate of a carrier gas
Question 2
Which of the following is not a type of detector used in gas chromatography?
A. Argon ionisation detector
B. Thermal conductivity detector
C. UV visible spectrometric detector
D. Electron capture detector
Question 3
Flame ionisation detector is also known as Katharometer.
A. True
B. False
Question 4
Doubling the column's length increases resolution by a factor of
A. (2)0.5
B. 2
C. 3
D. 4
Question 5
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
Question 6
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
Question 7
The GC trace obtained after an experiment is called a
A. chromatograph
B. chromatogram
C. chromatophore
D. graph
Question 8
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
Question 9
Which of the following is not used for detection in GC?
A. Infrared spectroscopy
B. NMR
C. Flame ionisation
D. Electrical conductivity
Question 10
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
Question 11
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
Question 12
Which of the following detectors give concentration-dependent signals?
A. Electron-capture detector
B. Thermal conductivity
C. Infra-red detector
D. All of these
Question 13
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
Question 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
Question 15
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
Question 16
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
Question 17
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
Question 18
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
Question 19
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
Question 20
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
Question 21
Sample retention in the column is measured by
A. retention time
B. retention factor
C. retention index
D. all of these
Question 22
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
Question 23
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
Question 24
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
Question 25
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
Question 26
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
Question 27
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
Question 28
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
Question 29
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
Question 30
Capillary columns are open tubular columns constructed from which of the following materials?
A. Glass
B. Metal
C. Stainless steel
D. Fused silica
Question 31
For the separation of which of the following substances, Gas-solid chromatography is being used?
A. Thermally stable organic components
B. Volatile organic components
C. Thermally stable inorganic components
D. Low molecular weight gaseous species
Question 32
In which of the following methods are liquid samples injected into the column in gas chromatography?
A. Gas tight syringe
B. Micro-syringe
C. Rotary sample valve
D. Solid injection syringes
Question 33
Sample injection port must be maintained at a temperature at which rapid vapourisation occurs but thermal degradation does not occur.
A. True
B. False
Question 34
Slow injection of large samples leads to band broadening and loss of resolution.
A. True
B. False
Question 35
What must be done to the solid samples for it to be introduced into the column without using solid injection syringes in gas chromatography?
A. Introduced in hot-zone of the column
B. Dissolved in volatile liquids
C. Introduced using rotary sample valve
D. Introduced using sampling loops
Question 36
Which of the following is not a desirable feature of the ovens used in gas chromatography?
A. It must have a fast rate of heating
B. Power consumption should be kept low
C. It must have maximum thermal gradients
D. It should have proper insulation
Question 37
Which of the following is not a feature of carrier gas used in gas chromatography?
A. It must be chemically inert
B. It should be suitable for the detector employed
C. It should not be completely pure
D. It should be cheap
Question 38
Which of the following is the advantage of a straight packed column?
A. It can be packed uniformly
B. It can be repacked easily
C. It is compact
D. It is easier to heat it evenly
Question 39
Which of the following is the commonly used support material for the packed column in gas chromatography?
A. Glass
B. Metal
C. Diatomaceous earth
D. Stainless steel
Question 40
Which of the following is the disadvantage of coiled or helical shaped packed chromatographic column?
A. It cannot be packed uniformly
B. It cannot be repacked easily
C. It is not compact
D. It is not easy to heat it evenly
Question 41
Which of the following is the disadvantage of helium, which can be used as carrier gas in gas chromatography?
A. Dangerous to use
B. Expensive
C. Reduced sensitivity
D. High density
Question 42
Which of the following is the disadvantage of hydrogen, which can be used as carrier gas in gas chromatography?
A. Dangerous to use
B. Expensive
C. Reduced sensitivity
D. High density
Question 43
Which of the following is the disadvantage of nitrogen, which can be used as carrier gas in gas chromatography?
A. Dangerous to use
B. Expensive
C. Reduced sensitivity
D. High density