Solution

Intramolecular hydrogen bonding takes place within the same molecule and occurs only when the two functional groups are close to each other in the molecule.
In HF, only intermolecular hydrogen bonding is possible.
In m-nitrophenol and p-nitrophenol, the $-NO_2$ and $-OH$ groups are far apart, so intramolecular hydrogen bonding is not possible.
In o-nitrophenol, the $-NO_2$ and $-OH$ groups are on adjacent carbon atoms, so they form intramolecular hydrogen bonding.
So intramolecular hydrogen bonding is present in o-nitrophenol (2-nitrophenol).

Concept Identifying intramolecular H-bonding in substituted phenols

Chemical Bonding and Molecular Structure in past papers

108 questions from this chapter have appeared across 27 exam years.