1. Intermolecular forces: The strength of the intermolecular forces between the molecules of a liquid determines its viscosity and boiling point. Liquids with strong intermolecular forces tend to be more viscous and have higher boiling points, while liquids with weak intermolecular forces tend to be less viscous and have lower boiling points.

2. Temperature: The temperature of a liquid also affects its behavior. As temperature increases, the kinetic energy of the molecules increases and the intermolecular forces become weaker. This causes the liquid to become less viscous and have a lower boiling point.