#"Intermolecular forces"# are the forces between molecules, and the normal boiling point and melting point of a molecule are useful metrics to interrogate this interaction.
On the hand, #"intramolecular forces"# are the forces WITHIN molecules; i.e. the forces between #N-H# and #N-N# versus #C-H# and #C-C# bonds. Most syllabuses make this distinction very clearly.
As regards the #"intermolecular force"#, perhaps the best metric we can use for comparison is the #"normal boiling point"#, i.e. the temperature at which the vapour pressure of the material is #1*atm#.
The normal boiling point of ethylene is #-103.7# #""^@C#.
The normal boiling point of hydrazine is #114# #""^@C#.
These materials have more or less equivalent molecular mass, yet the difference in volatility is striking. So what has hydrazine (and water) got that ethylene ain't got? The answer is #"hydrogen bonding"#, where hydrogen is bound to a strongly electronegative element such as fluorine, or oxygen, or nitrogen. Hydrogen bonding constitutes a potent intermolecular force that elevates the boiling point.
