In demonstrations of strong and weak electrolytes and nonelectrolytes, a lightbulb apparatus that shows how much a solution conducts electricity by the brightness of the light is often used. When pure water is tested, the bulb does not light. When some acetic acid is added to the water, the bulb burns dimly. When more acetic acid is added to the solution, the bulb burns a little more brightly. In a separate experiment, if pure acetic acid is tested, what would be observed