Final answer:
The viscosity of a gas increases with temperature due to more frequent and energetic molecular collisions, while in liquids, it decreases as higher temperatures reduce intermolecular forces.
Step-by-step explanation:
The question touches upon the concept of viscosity, which describes a fluid's resistance to flow. In liquids, viscosity decreases with temperature because increased kinetic energy at higher temperatures allows the molecules to overcome intermolecular forces (IMFs), making it easier for them to move past each other.
In contrast, the viscosity of a gas increases as it warms up because the additional kinetic energy leads to more frequent and energetic collisions between the atoms and molecules, thus increasing the gas's resistance to flow.