Why p-nitro toluene is higher boiling point than o-nito toluene ?
 
Ans) The term hydrogen bonding is used to define dipole-dipole attractive forces of this type. The proton involved must be bonded to an electronegative element, usually oxygen or nitrogen.

Protons in C-H bonds do not participate in hydrogen bonding.  Hydrogen bonding can be expected in molecules that have -OH or - NH groups . so there is no hydrogen bond in the o-nitrotoluene