Which of the following compounds exhibits hydrogen bonding?

Hydrogen bonding is formed in compounds containing hydrogen and

Maximum number of hydrogen bonds in $H_2O$ is

Assertion : Boiling point of $p$-nitrophenol is higher than that of $o$-nitrophenol.
Reason : $p$-nitrophenol has intermolecular hydrogen bond whereas $o$-nitrophenol has intramolecular hydrogen bond.

The variation of the boiling points of the hydrogen halides is in the order $HF > HI > HBr > HCl$. What explains the higher boiling point of hydrogen fluoride?

In which of the following is intermolecular $H$-bonding present?