6. An isocratic elution in HPLC is one in which the composition of the solvent

A. remains constant
B. changes continuously
C. changes in a series of steps
D. none of these

7. In reversed 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

8. Which of the following statements is true for a refractive index detector in HPLC?

A. It is more sensitive than a UV detector
B. It can only be used for isocratic elutions
C. It does not respond to many solutes
D. none of above

9. 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

10. 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