931. Which of the following detectors give concentration-dependent signals?
A. Electron-capture detector
B. Thermal conductivity
C. Infra-red detector
D. All of these

932. 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

933. 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

934. 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

935. 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

936. 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

937. 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

938. 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

939. 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

940. 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

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