Science Olympiad Green Generation Practice Test

The correct answer is based on the principle of electrodialysis, which utilizes an electric potential difference to facilitate the movement of ions. In electrodialysis, an electric field is applied across two electrodes, creating a potential difference that drives the migration of ions through selective ion-exchange membranes. Cation exchange membranes allow positively charged ions to pass through while restricting negatively charged ions, and anion exchange membranes do the opposite. This separation process is effective in purifying water by removing specific ions, making it a valuable method in water treatment and desalinization scenarios.

Filtration, while it is a common method for separating particles from fluids, relies on physical barriers rather than electric potential to achieve separation. Adsorption involves the adhesion of ions or molecules from a solution to a solid surface but does not employ an electric field. Reverse osmosis utilizes a pressure differential across a semi-permeable membrane to separate contaminants from water, but again, it does not involve the use of an electric potential difference like electrodialysis does. Therefore, electrodialysis distinctly stands out for its reliance on electrical potential to remove ions from a solution.