921. A gradient elution in HPLC is one in which the composition of the solvent
A. remains constant
B. is changed continuously or in a series of steps
C. both (a) and (b)
D. none of the above

922. An eluotropic series
A. ranks solvents by their relative abilities to displace solutes from a given absorbent
B. ranks column packing material by their relative abilities to retain solutes on the column
C. is a measure of the solvent adsorption energy
D. none of the above

923. Dwell volume is defined as
A. the volume of solvent contained in a liquid chromatographic column
B. the time required for the gradient to reach the column
C. the volume of the column between the point at which solvents are mixed and the beginning of the column
D. none of these

924. Void volume refers to the
A. total volume of eluent in the column the remainder being taken up by the packing material
B. the volume of solvent contained in a liquid chromatographic column
C. the time required for the gradient to reach the column
D. the volume of the column between the point at which solvents are mixed and the beginning of the column

925. In normal phase HPLC, there is a
A. non polar solvent/polar column
B. polar solvent/non-polar column
C. non polar solvent/non-polar column
D. any of the above

926. Which of the following(s) is/are the advantage of HPLC over traditional LPLC (low-pressure liquid chromatography)?
A. Greater sensitivity and reusable columns
B. Ideal for ionic species and large molecules
C. Sample recovery
D. All of the above

927. Which can be used as a mobile phase in HPLC applications?
A. Any compound with solubility in liquid
B. Any compound with limited solubility in liquid
C. Any compound with non-solubility in liquid
D. Any of the above

928. Which of the following is not used for detection in GC?
A. Infrared spectroscopy
B. NMR
C. Flame ionisation
D. Electrical conductivity

929. 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

930. The GC trace obtained after an experiment is called a
A. chromatograph
B. chromatogram
C. chromatophore
D. graph

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