As the electrolyte level in the cells of a lead-acid battery evaporates over time, what will tend to happen to the specific gravity of the electrolyte in the cells as the level drops due to evaporation?

Correct Answer: Option D — The specific gravity of the electrolyte will increase as only the water will evaporate from the electrolyte solution.

Water evaporates from the aqueous sulfuric acid electrolyte over time, while the heavy sulfuric acid remains in solution. Consequently, the volume of solvent decreases while the amount of solute stays constant, raising the resulting specific gravity.