Which observation using a conductivity apparatus indicates that a solution contains ionic substances rather than covalent substances?

• A. The solution produces bubbles at the electrodes.
• B. The solution conducts electricity, causing the light bulb to glow brightly.
• C. The solution does not conduct electricity, and the light bulb remains off.
• D. The solution changes color when the electrodes are inserted.

Answer: (B)

Verified step by step guidance

1. Understand that ionic substances dissociate into ions when dissolved in water, and these ions are charge carriers that allow the solution to conduct electricity.
2. Recognize that covalent substances generally do not produce ions in solution, so they do not conduct electricity well, resulting in little or no current flow.
3. Using a conductivity apparatus, observe whether the solution allows electric current to pass through by checking if the light bulb glows.
4. If the light bulb glows brightly, it indicates the presence of free ions in the solution, which is characteristic of ionic substances.
5. If the light bulb does not glow or glows very dimly, it suggests the solution contains mostly covalent substances that do not ionize significantly.