16. 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

17. 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

18. 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 the above

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

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