What neutralizes the electrolyte from a nickel-cadmium battery?

The correct choice of a solution of boric acid or other mild acid effectively neutralizes the electrolyte from a nickel-cadmium battery due to the acidic nature of the electrolyte itself, which is typically potassium hydroxide (a strong alkali). When a mild acid, such as boric acid, is introduced to the alkaline electrolyte, a neutralization reaction occurs. This reaction converts the caustic properties of the electrolyte into more manageable compounds, thus rendering the electrolyte less hazardous and safer to handle.

Using pure water, while it can dilute the electrolyte, does not neutralize it because water alone does not change the pH of the strong alkaline solution. A solution of bleach could introduce further chemical reactions that might not effectively neutralize the alkalinity. Conversely, a basic sodium solution would not neutralize the electrolyte but rather exacerbate the alkaline environment, leading to potential safety hazards if mixed with a nickel-cadmium battery’s electrolyte. Hence, a mild acid is the most appropriate choice for neutralizing the electrolyte in this situation.