(I)1, 2-dihydroxy benzene(II) 1, 3-dihydroxy benzene(III) 1, 4-dihydroxy benzene(IV) Hydroxy benzeneThe increasing order of boiling points of above mentioned alcohols is

1, 4-dihydroxy benzene shows the highest boiling point among given compounds because it forms strong intermolecular hydrogen bonds (It does not form intermolecular H-bonding.)