Which of the following compounds has the highest boiling point. 2pentanone, pentanol, pentane, and pentanal

            1-Pentanol has the highest boiling point.

Explanation:
                   Boiling points of given compounds are as follow,

                 1) 2-Pentanone  =  101 °C

                 2) 1-Pentanol  =  138 °C

                 3)  Pentane  =  36.1 °C

                 4)  Pentanal  =  103 °C

Pentanol has greatest boiling point as compare to others because it involes a strongest intermolecular interactions called as hydrogen bond interactions. Remaining compounds lack the direct attachement of hydrogen to most electrnegative atom like oxygen which is present in 1-Pentanol.

All the elements are arranged by melting points on the periodic table. in row they go from metals to gasses. in the row from sodium to argon, sodium is more reactive than the one on its right, magnesium.