A concentration gradient happens when there is a change of the concentration in solution for period of time. Diffusion is the movement of molecules or ions. The relationship between the two of them is molecules diffuse down from an area with a higher concentration to a lower one. An example of this is putting dye in water.
Answer:
the correct answer is CO2 (the last one)
Dissolving an ionic compound is a chemical change. In contrast, dissolving sugar or another covalent compound is a physical change because chemical bonds are not broken and new products are not formed .Dissolving a solid in liquid, such as table salt in water, is a physical change because only the state of the matter has changed. Physical changes can often be reversed. ... It has not combined with the water to cause a chemical reaction
