The corrosion of iron object is favoured by

Options

A. Presence of `H^(+)` ion
B. Presence of moisture in air
C. Presence of `CO_(2)` in air
D. All of these

Answer

To solve the question regarding what factors favor the corrosion of iron objects, we can analyze each option provided.

### Step-by-Step Solution:

1. **Understanding Corrosion**:
- Corrosion is defined as the slow degradation of metal surfaces due to environmental factors, primarily the attack of oxygen and moisture. In the case of iron, this process leads to the formation of rust (iron oxide).

2. **Analyzing the Options**:
- **Option 1: Presence of H⁺ ions**:
- The presence of H⁺ ions can contribute to the corrosion process by increasing the acidity of the environment, which can accelerate the oxidation of iron. Therefore, this option is correct.

- **Option 2: Presence of moisture in air**:
- Moisture is a critical factor in corrosion because it facilitates the electrochemical reactions that lead to rust formation. Water acts as an electrolyte, allowing ions to move and participate in the corrosion process. Thus, this option is also correct.

- **Option 3: Presence of CO₂ in air**:
- CO₂ can dissolve in water to form carbonic acid, which can lower the pH of the solution and promote corrosion. This means that the presence of CO₂ can also favor the corrosion of iron. Hence, this option is correct as well.

- **Option 4: All of these**:
- Since all the previous options contribute to the corrosion process, this option must be correct.

3. **Conclusion**:
- Therefore, the corrosion of iron objects is favored by the presence of H⁺ ions, moisture in the air, and CO₂ in the air. The correct answer is **Option 4: All of these**.

### Final Answer:
The corrosion of iron object is favored by **Option 4: All of these**.

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