Question

Active materials of a lead acid cell are

• A. spongy lead
• B. lead peroxide
• C. dilute H2SO4
• D. all of these

Hint:

In a lead-acid battery, spongy lead, lead peroxide, and dilute sulfuric acid are the key active materials.

Answer 1

The Correct Option is D

A lead-acid cell has exactly three functionally distinct active components: the negative-plate material, the positive-plate material, and the electrolyte. All three change chemically as the cell charges or discharges, which is what qualifies each of them as "active" (as opposed to passive structural parts like the plate grids or the container).

1. Spongy lead: Serves as the negative-plate active material, one of the three functional components.
2. Lead peroxide: Serves as the positive-plate active material, the second of the three components.
3. Dilute H2SO4: Serves as the active electrolyte, the third component, which also changes concentration as the cell operates.
4. All of these: Since a complete, working lead-acid cell needs all three of these active materials together to function at all, none of them alone is sufficient — they must all be present.

Checking off all three necessary functional components confirms that all three are active materials.

Therefore, the correct answer is all of these.

Answer 2

Another way to confirm this is to ask: if any one of these three substances were removed, would the cell still work as a lead-acid cell? Let's check each option against this test.

1. Spongy lead: Without the spongy lead negative plate, there is no material to oxidize during discharge, so the cell cannot function — this confirms it is essential and active.
2. Lead peroxide: Without lead peroxide at the positive plate, there is nothing to be reduced during discharge, so this too is essential and active.
3. Dilute H2SO4: Without the sulfuric acid electrolyte, there would be no medium to carry ions between the plates and no acid to react with the plate materials, so the cell could not operate either.
4. All of these: Since removing any single one of the three substances stops the cell from working, all three must be essential, active materials together.

This removal test confirms that none of the three materials is optional — they are all active materials of the cell.

Therefore, the correct answer is all of these.