Four organic compounds: 2-butanone, n-pentane, propanoic acid, and n-butanol, present as a mixture, are separated by column chromatography using silica gel with benzene as the eluent. what is the expected order of elution of these four organic compounds from first to last? a. n-pentane → 2-butanone → n-butanol → propanoic acid b. n-pentane → n-butanol → 2-butanone → propanoic acid c. propanoic acid → n-butanol → 2-butanone → n-pentane d. propanoic acid → 2-butanone → n-butanol → n-pentane