Which type of solution has an equal concentration of particles?

The correct answer is isotonic because this term specifically refers to a solution that has an equal concentration of solute particles when compared to another solution, typically the cytoplasm of a cell or another fluid space. In a biological context, maintaining an isotonic environment is crucial because it ensures that there is no net movement of water into or out of cells, thus preventing cell swelling or shrinkage.

In comparison, hypotonic solutions contain a lower concentration of solute particles compared to another solution, which can lead to water moving into the cells and potentially causing them to burst. Conversely, hypertonic solutions have a higher concentration of solute particles, resulting in water moving out of the cells and causing them to shrink. Supersaturated solutions exceed the usual concentration of solutes that can dissolve in a solvent, but do not maintain the equilibrium characteristic of isotonic solutions. This distinction highlights why isotonic is the correct choice, as it directly addresses the specific scenario of equal concentrations of solute particles.