What is the maximum number of hydrogen bonds in which a single water molecule can participate?

Which of the following compounds exhibits hydrogen bonding?

In which of the following compounds does hydrogen bonding occur?

$o-$nitrophenol can be easily steam distilled whereas $p-$nitrophenol cannot be. This is because of

Hydrogen bonding plays a central role in the following phenomena:
$(A)$ Ice floats in water.
$(B)$ Higher Lewis basicity of primary amines than tertiary amines in aqueous solutions.
$(C)$ Formic acid is more acidic than acetic acid.
$(D)$ Dimerisation of acetic acid in benzene.

The strongest intermolecular hydrogen bond is present in which of the following pairs of molecules?