Question

Electrolyte used in lead acid battery is

• A. Sulphuric acid
• B. Caustic potash
• C. Nitric Acid
• D. Hydrochloric acid

Hint:

The "health" of a lead-acid battery is often checked using a hydrometer to measure the specific gravity of the sulphuric acid. A full charge typically shows a specific gravity of around 1.28.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
A lead-acid battery is a secondary (rechargeable) cell. It requires a liquid medium called an electrolyte to allow the flow of ions between the positive and negative plates during charging and discharging.

Step 2: Detailed Explanation:
In a lead-acid battery, the positive plate is Lead Peroxide ($\text{PbO}_2$) and the negative plate is Spongy Lead ($\text{Pb}$). To facilitate the chemical reaction, they are immersed in a solution of Dilute Sulphuric Acid ($\text{H}_2\text{SO}_4$). During discharge, the acid reacts with the plates to form lead sulphate and water, which is why the specific gravity of the electrolyte drops as the battery loses charge.

Step 3: Final Answer:
The electrolyte used is sulphuric acid.