Question

when sodium is pumped out of a nerve cell is that an example of diffusion osmosis or active transport

Answer 1

Active transport, because it is using energy in order to pump it out :) @Madeline818

Answer 2

And for future references, just remember that diffusion and osmosis do not take energy. Diffusion does not take energy because it is simply going across a lipid bilayer. From high concentration to low concentration. Osmosis does not take energy because it is just "sliding down" the concentration gradient. That's just how I remember it. :)