Nitrogen , oxygen and fluorine are the highly electronegative elements. When they are tied to a hydrogen atom to form covalent bond, the electrons of the covalent bond are shifted towards the more electronegative atom.This partially positively charged hydrogen atom forms a bond with the other electronegative atom. This bond is called as hydrogen bond and is weaker than covalent bond.For example, in HF molecule, thehydrogen bond exists between hydrogen atom of one molecule and fluorine atom of another molecule as depicted ---H^(delta+)-F^(delta-)---H^(delta+)-F^(delta-)---H^(delta+)-F^(delta-) Here, hydrogen bond acts as bridge between atoms which holds one atom by covalent bond and the other by hydrogen bond.Hydrogen bond is represented by a dotted line (---) while a solid line represents the covalent bond. Thus, hydrogen bond can be defined as the attractive force which binds hydrogen atom of one molecule with the electronegative atom (F,O and N) of another molecule. If boiling point of ortho-nitro phenol and para nitro phenol are t_1 and t_2 respectively and mixture of these two are heated at temperature 't' where 't' is between these two temperature.Vapours will significantly contains