The process where a nonpolar molecule can passively get across a membrane is called simple diffusion.

Here's why:

* Simple diffusion is the movement of a substance from an area of high concentration to an area of low concentration. This movement happens passively, meaning it doesn't require any energy input from the cell.

* Nonpolar molecules are hydrophobic, meaning they don't interact well with water (which makes up the majority of the cell membrane). This makes them able to slip through the lipid bilayer of the cell membrane relatively easily.

Let me know if you have any other questions!