Chemistry Regents Practice Test 2026 – Complete Prep Resource

The process of diffusion is characterized by the movement of particles from an area of high concentration to an area of low concentration. This movement occurs naturally as the particles aim to achieve equilibrium within the medium they occupy. As particles spread out, they move down their concentration gradient, which is a driving force for diffusion. This process does not require energy input, as it is driven by the innate kinetic energy of the particles—thus, it is classified as a passive transport mechanism.

In contrast, other options describe either active processes or characteristics related to concentration but do not accurately represent diffusion. Movement against a concentration gradient requires energy and is indicative of active transport, while an unequal distribution of particles can be a condition that leads to diffusion rather than a definition of it. Similarly, movement that requires energy input does not apply to diffusion, as the process is inherently passive.