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.