Chemistry Regents Practice Test 2026 – The All-in-One Guide to Exam Success!

A concentration gradient indicates a difference in the concentration of a substance across a particular space. Specifically, it describes a scenario where there is a higher concentration of a substance in one area compared to another area. This difference in concentration can drive the movement of particles from an area of higher concentration to an area of lower concentration, a process known as diffusion. Understanding concentration gradients is essential for various biological and chemical processes, such as the exchange of gases in the lungs or the absorption of nutrients by cells. In contrast, if there were equal concentrations in both areas, there would be no concentration gradient present, which is not what the question describes. The other options reference concepts that do not directly relate to the definition of a concentration gradient.