The given reaction occurs in a car battery when it is used to produce electricity.
`Pb + PbO_2 + 2H_2 SO_4 to 2PbSO_4 + 2H_2 O`
Which of the following statements are incorrect about this reaction?
I. Pb is acting as an oxidising agent.
II. `H_2 SO_4` is acting as a reducing agent.
III. The reaction is a precipitation reaction.
IV. `PbO_2` oxidises Pb to `PbSO_4`

Options

A. III and IV only
B. I and II only
C. I and III only
D. I, II, III and IV

Answer

To determine which statements are incorrect about the given reaction in a car battery, we will analyze each statement one by one.

**Given Reaction:**
\[ \text{Pb} + \text{PbO}_2 + 2\text{H}_2\text{SO}_4 \rightarrow 2\text{PbSO}_4 + 2\text{H}_2\text{O} \]

### Step 1: Analyze Statement I
**Statement I:** Pb is acting as an oxidizing agent.

- In the reaction, lead (Pb) is being oxidized from an oxidation state of 0 to +2 in PbSO4.
- An oxidizing agent is a substance that gains electrons and is reduced in the process. Since Pb is losing electrons, it is acting as a reducing agent, not an oxidizing agent.

**Conclusion for Statement I:** Incorrect.

### Step 2: Analyze Statement II
**Statement II:** H2SO4 is acting as a reducing agent.

- In this reaction, sulfur in H2SO4 remains in the +6 oxidation state before and after the reaction. There is no change in oxidation state for sulfur or any other element in H2SO4.
- A reducing agent must undergo a decrease in oxidation state, which is not the case here.

**Conclusion for Statement II:** Incorrect.

### Step 3: Analyze Statement III
**Statement III:** The reaction is a precipitation reaction.

- A precipitation reaction occurs when two soluble salts react to form an insoluble salt. In this case, PbSO4 is formed, which is insoluble in water.
- Therefore, this reaction does indeed produce a precipitate.

**Conclusion for Statement III:** Correct.

### Step 4: Analyze Statement IV
**Statement IV:** PbO2 oxidizes Pb to PbSO4.

- PbO2 is in the +4 oxidation state and is acting as an oxidizing agent because it facilitates the oxidation of Pb (0) to Pb(+2).
- Since PbO2 is gaining electrons (it is reduced), it is indeed oxidizing Pb.

**Conclusion for Statement IV:** Correct.

### Summary of Statements:
- Statement I: Incorrect
- Statement II: Incorrect
- Statement III: Correct
- Statement IV: Correct

### Final Answer:
The incorrect statements about the reaction are **I and II**.

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