Order of boiling point for the following compounds is

IV < I < II < III

• 1,4 -dihydroxy benzene has inter molecular H-bonding so it has highest B.P. than 1,2 - dihydroxy benzene has intra molecular H-bonding.
• 1,3 -dihydroxy benzene has partially  inter molecular H-bonding and partially intra molecular H-bonding.si it is more than 1,2 - dihydroxy benzene and less than 1,4 -dihydroxy benzene
• Phenol does not have any H- bonding
• so Para>meta>ortho