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

Step 1: Components of a lead acid cell.
The active materials in a lead-acid cell include spongy lead (Pb) on the negative plate, lead peroxide (PbO₂) on the positive plate, and sulfuric acid (H₂SO₄) as the electrolyte.
Step 2: Conclusion.
Thus, all the given materials are part of a lead-acid cell, corresponding to option (D).

Answer 2

We can identify the active materials by looking at the overall reversible reaction of a lead-acid cell: \[ \text{Pb} + \text{PbO}_2 + 2\text{H}_2\text{SO}_4 \rightleftharpoons 2\text{PbSO}_4 + 2\text{H}_2\text{O}. \] Every substance appearing on the reactant side that participates directly and gets consumed/transformed during discharge is an "active material." Let's check each option against this reaction.

1. Spongy lead: Spongy (porous) lead, Pb, is the active material at the negative plate — it appears directly as a reactant in the discharge reaction.
2. Lead peroxide: Lead peroxide, PbO₂, is the active material at the positive plate — it also appears directly as a reactant.
3. Dilute H2SO4: Dilute sulfuric acid is the active material of the electrolyte — it too is consumed directly in the discharge reaction, being converted along with the plate materials into lead sulfate and water.
4. All of these: Since spongy lead, lead peroxide, and dilute sulfuric acid all appear as reactants that are directly consumed in the cell's discharge reaction, all three qualify as active materials together.

The discharge reaction shows that spongy lead, lead peroxide, and dilute sulfuric acid are all directly involved as active materials.

Therefore, the correct answer is all of these.