Advanced Placement (AP) Chemistry Practice Exam 2025 - Free AP Chemistry Practice Questions and Study Guide

Electrolytes are substances that dissociate into ions when dissolved in water, resulting in a solution that can conduct electricity. The key characteristic that distinguishes electrolytes is their ability to facilitate the movement of charged ions in solution. When an electrolyte dissolves, it produces cations and anions, which are free to move in the solution and carry electrical current. This movement of charged ions is fundamental to the conductivity of electrolytic solutions and is essential for various chemical and biological processes.

In contrast, other properties mentioned do not accurately describe electrolytes. Insolubility in water does not pertain to electrolytes; rather, it is typically characteristic of non-electrolytes or substances that do not produce ions in solution. Conductivity in solid form is not characteristic of typical electrolytes, as their ionic form needs to be dissociated in a solvent to exhibit conductivity. Lastly, the ability to change color in the presence of acids is a property more related to indicators or pH-sensitive substances rather than to the fundamental nature of electrolytes. Thus, the correct assertion highlights the significance of charged ion mobility in a solution, which is crucial for understanding electrolyte behavior in chemistry.