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21. In a reversed-phase column, the retention factor k of a solute was found to be 24 when the mobile phase was 50% (by volume) methanol and 50% water. Calculate an acetonitrile/water composition that should bring k to a value of about 6. Solvent H20 CH,CN CH,OH P 10.2 A. 74% methanol/26% water B. 26% methanol /74% water C. 61% methanol/39% water D. 39% methanol/ 71% water E. 82% methanol / 19% water 5.8 THF 4.0 5.1 22. Apply the r + d algorithm to the compound CH2C12N0 to determine its degrees of unsaturation. A. 0.5 B. 1.0 C. 1.5 D. 2.0 E. 3.0 23. Liquid column chromatography on alumina would separate p-nitrotoluene and p-nitroaniline A. only slightly since the molecules are nearly the same size. B. with p-nitroaniline eluted first since the stationary phase has little affinity for polar compounds. c. with p-nitrotoluene eluted first since the stationary phase absorbs polar compounds strongly, D. with p-nitrotoluene eluted first since it has a lower boiling point. E. with p-nitroaniline eluted first since equilibria in the moving phase involve ions.