which molecules would most likely cause a liquid to have the lowest viscosity?
large, polar molecules
small, nonpolar molecules
small, polar molecules
large, nonpolar molecules

small, non polar molecules

A liquid has the ability to flow because its molecules can slide over each other. The resistance to such flow is called the viscosity. Liquids which flow very slowly, like glycerin or honey, have high viscosity and those like ether or gasoline which flow very smoothly have low viscosity.

Viscosity is governed by the strength of inter-molecular forces. So liquids whose molecules are polar can form hydrogen bonds are usually more viscous because they need more energy to break their bonds but on the other hand similar non-polar substances have weak inter-molecular forces and they can easily slide over each other resulting in low viscosity.