Final answer:
The viscosity of a liquid decreases with temperature as increased temperature reduces the effects of cohesive forces. Conversely, the viscosity of a gas increases with temperature as higher temperature creates more collisions between particles.
Step-by-step explanation:
The viscosity of a liquid decreases with temperature because increased temperature reduces the effects of cohesive forces in the liquid. As the temperature increases, the molecules in the liquid move more rapidly, and their kinetic energies are better able to overcome the forces holding them together. This leads to a decrease in viscosity.
On the other hand, the viscosity of a gas increases with temperature because increased gas temperature creates more collisions between atoms and molecules. Higher temperature means higher kinetic energy of the gas particles, leading to more frequent and energetic collisions, which in turn increases the viscosity of the gas.