Arrange the following compounds in order of increasing boiling point:
I.1-propanol,CH₃CH₂CH₂OH;
II.1,2-propanediol,CH₃CH(OH) CH₂OH;
III.1,2,3-propanetriol, (glycerol) ,HOCH₂CH(OH) CH₂OH.

Question

Quizplus · Accepted Answer

The boiling point of compounds depends on their intermolecular forces. The strength of intermolecular forces increases with increasing polarity and increasing number of hydrogen bonds. 
Among the given compounds, 1-propanol can form hydrogen bonding with itself due to the presence of the hydroxyl (-OH) group. In 1,2-propanediol, two hydroxyl groups are present which can form more extensive hydrogen bonding than 1-propanol. In 1,2,3-propanetriol or glycerol, three hydroxyl groups are present, which can form even more extensive hydrogen bonding than 1,2-propanediol. 
Therefore, the increasing order of boiling points is I < II < III. 
Hence, the correct answer is choice B.

Arrange the Following Compounds in Order of Increasing Boiling Point