Arrange the following compounds in the increasing order of their boiling points :
`CH_(3)CH_(2)CH_(2)CHO, CH_(3)CH_(2)CH_(2)CH_(2)OH, H_(5)C_(2)-O-C_(2)H_(5), CH_(3)CH_(2)CH_(2)CH_(2)CH_(3)`.

Explanation

The molecular masses of these compounds are in the range of 72 to 74. Since only butan-1-ol molecules are associated due to extensive intermolecular H-bonding, therefore, the boiling point of butan-1-ol would be the highest. Butanal is more polar than ethoxyethane. Therefore, the intermolecular dipole-dipole attraction is stronger in the former. n-Pentane molecules have only weak van der waals forces. hence increasing order of boiling points of the given compounds is as follows :
`CH_(3)CH_(2)CH_(2)CH_(2)CH_(3) lt H_(5)C_(2) - O-C_(2)H_(5) lt CH_(3)CH_(2)CH_(2)CHO lt CH_(3)CH_(2)CH_(2)CH_(2)OH`