In solution equilibrium, the rate of dissolution equals the rate of crystallization.

• A. Dissolution and crystallization occur at equal rates
• B. Light scattering by colloidal particles
• C. Electric current is produced in solution
• D. Solute particles are too large to pass through the filter

Answer: (A)

In solution equilibrium, dissolution and crystallization occur at equal rates, so the amount of solute dissolved in the solvent stays constant over time even though both processes are happening. This dynamic balance means the solution is saturated at that temperature, and the observed concentration doesn’t change unless conditions like temperature or pressure change. The other ideas describe unrelated phenomena: light scattering by colloidal particles is about colloids and the visible scattering of light, not the balance between solid and dissolved phases; electric current in solution would require charge flow from electrode processes rather than a steady exchange between solid and dissolved species; and solute particles being too large to pass through a filter is a filtration issue, not a statement about equilibrium between dissolution and crystallization.