In which of the following pure substances will hydrogen bonding be an important intermolecular force?

Hydrogen bond is the force between two molecules.  One of the molecules has an F, N or O atom which is very electronegative, while another molecule has a H atom which carries a rather high partial positive charge.

1) false
CH₂Cl₂ does not have F, N or O atom.

2) true
The H atom is bonded to very electronegative O atom, and thus carries a rather high partial positive charge.  There is hydrogen bond between the H atom of a molecule and the O atom of another molecule.

3) true
The H atom is bonded to very electronegative N atom, and thus carries a rather high partial positive charge.  There is hydrogen bond between the H atom of a molecule and the N atom of another molecule.

4) false
The H atom is not positive enough because there are 9 H atoms indirectly attached to the N atom.

The answer: 2 and 3