Ni-Cd battery electrolyte can be neutralized by using which chemical?

• A. Boric acid
• B. Sodium hydroxide
• C. Hydrochloric acid
• D. Ammonium chloride

Answer: (A)

Ni-Cd battery electrolyte is alkaline, typically potassium hydroxide. To neutralize an alkaline solution, you add an acid so the hydroxide ions form water and a salt. Boric acid is used because it’s a weak acid that gently neutralizes the base, forming stable borate salts and water without a large heat release or aggressive reactions. This makes cleanup safer and less corrosive to the battery materials.

Sodium hydroxide would not neutralize it; it would add more base. Hydrochloric acid is a strong acid and would neutralize quickly, but can cause strong heat and potential corrosion or other reactions with battery components. Ammonium chloride would react to form ammonium salts and ammonia gas in this context, which is undesirable.