Question

What is brownian motion?

Answer 1

The zigzag  motion of particles in air or water when hit by the molecules of air or water is called Brownian motion.
Ex: when we see dust particles in air due to sunlight..we can see zigzag motion of dust due to collision of air molecules with dust particles.

Answer 2

the erratic random movement of microscopic particles in a fluid is called brownian motion...........