$21.$ Injection of ethane, propane, butane, pentane, hexane, heptane, and octane on a squalene column under isothermal conditions gives retention times of $3\mathrm{.}51,4\mathrm{.}98,7\mathrm{.}30,11\mathrm{.}00,16\mathrm{.}85,26\mathrm{.}12,$ and $40\mathrm{.}8$min, respectively. Air, which is nonretained, elutes at $1\mathrm{.}00$min. An injection of benzene, butanol, nitropropane, pyridine, and $2-$pentanone under the same conditions gives retention times of $20\mathrm{.}00,6\mathrm{.}50,4\mathrm{.}10,10\mathrm{.}05,$ and $10\mathrm{.}35$min. What are the Kov$$ts retention indexes for benzene, butanol, nitropropane, pyridine, and $2-$pentanone