* Van der Waals forces: These are the primary intermolecular forces present in hydrocarbons. They arise from temporary fluctuations in electron distribution, creating temporary dipoles.

* Size and Surface Area: Larger molecules have greater surface area. This allows for more points of contact between molecules, leading to stronger Van der Waals forces.

* Molecular Weight: As molecular weight increases, the strength of Van der Waals forces also increases.

In summary: C16H34 is the largest molecule with the highest molecular weight, leading to the strongest Van der Waals forces and therefore the highest boiling point.