Question

Why viscosity increase as temperature increases in liquid decreases?

Answer 1

I would like to give the answer in an intuitive manner. Due to inter-molecular bonding in liquid there is a tight gaps that lead to resistive force(viscous force). so increase in temperature makes the molecules jiggle and create the spaces in between them. that means more spaces then less dragging force or less viscous.

But in case of gases, inter-molecular attraction is insignificant for the resistive force which is supposed to provide the viscous nature to the gas. so, increase in temperature leads to collision in between the gases molecules. Eventually that makes the gases more resistive in nature than before