Three compound X, Y and Z were taken into three different laboratory vessels annd they are carried out by a chemist in his car. The car caught fire due to short circuit and the chemist came out of the car and noticed following observations:
Q. Which of the following compound does not react with cold and dil. `HNO_(3)`?

Options

A. `PbO`
B. `PbO_(2)`
C. `FeSO_(4)`
D. `PbCl_(2)`

Explanation

To determine which compound does not react with cold and dilute HNO3, we will analyze each of the given compounds: PbO, PbO2, FeSO4, and PbCl2.

### Step-by-Step Solution:

1. **Understanding HNO3**:
- HNO3 (Nitric acid) is known to act as both an acid and an oxidizing agent. In reactions, it can oxidize certain compounds while itself getting reduced.

2. **Analyzing Each Compound**:
- **PbO (Lead(II) oxide)**:
- Lead in PbO is in the +2 oxidation state. It can be oxidized to +4 (PbO2) by HNO3. Therefore, PbO can react with cold and dilute HNO3.

- **PbO2 (Lead(IV) oxide)**:
- Lead in PbO2 is in the +4 oxidation state, which is the maximum oxidation state for lead. HNO3 cannot oxidize lead further because it cannot increase the oxidation state beyond +4. Therefore, PbO2 does not react with cold and dilute HNO3.

- **FeSO4 (Iron(II) sulfate)**:
- Iron in FeSO4 is in the +2 oxidation state. It can be oxidized to +3 (Fe2(SO4)3) by HNO3. Therefore, FeSO4 can react with cold and dilute HNO3.

- **PbCl2 (Lead(II) chloride)**:
- Lead in PbCl2 is also in the +2 oxidation state and can be oxidized to +4 (PbCl4) by HNO3. Therefore, PbCl2 can react with cold and dilute HNO3.

3. **Conclusion**:
- Among the compounds analyzed, **PbO2** is the only compound that does not react with cold and dilute HNO3 because it is already in its maximum oxidation state (+4).

### Final Answer:
**PbO2 does not react with cold and dilute HNO3.**

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