Which of the following reactions lead to chemical inertness :

Options

A. Lead with dilute `H_(2)SO_(4)`
B. Lead with conc. `HCI`
C. Aluminium with oxygen
D. All of above reactions

Explanation

To determine which reactions lead to chemical inertness, we need to analyze each reaction provided in the question. Chemical inertness refers to the inability of a substance to react chemically under certain conditions. Let's examine each reaction step by step.

### Step 1: Reaction of Lead with Dilute H2SO4
- **Reaction**: Pb + H2SO4 (dilute) → PbSO4 + H2↑
- **Analysis**: In this reaction, lead (Pb) reacts with dilute sulfuric acid (H2SO4) to form lead(II) sulfate (PbSO4), which is a solid precipitate. The formation of this solid layer can inhibit further reactions, leading to the inertness of lead in the presence of dilute H2SO4.

### Step 2: Reaction of Lead with Concentrated HCl
- **Reaction**: Pb + HCl (concentrated) → PbCl2 + H2↑
- **Analysis**: Here, lead reacts with concentrated hydrochloric acid (HCl) to form lead(II) chloride (PbCl2), which also forms a solid layer. This solid can act as a barrier, preventing further reaction and contributing to the inertness of lead in concentrated HCl.

### Step 3: Reaction of Aluminum with Oxygen
- **Reaction**: 4Al + 3O2 → 2Al2O3
- **Analysis**: In this reaction, aluminum reacts with oxygen to form aluminum oxide (Al2O3). Aluminum oxide is a stable compound that forms a protective layer on the surface of aluminum, making it resistant to further reactions with oxygen or other substances. This layer contributes to the inertness of aluminum in many environments.

### Conclusion
After analyzing all three reactions, we find that:
- The formation of solid layers (PbSO4, PbCl2, and Al2O3) in each case leads to chemical inertness.
- Therefore, all of the reactions listed contribute to the chemical inertness of the respective substances.

### Final Answer
All of the above reactions lead to chemical inertness.

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