Choose the incorrect statement about corrosion on the metal surface.

Options

A. In the corosion of iron, reduction of oxygen while oxidation of metal take place.
B. Rusting is reduced in highly alkaline medium.
C. `Mg` can act as sacrifical electrode.
D. `CO_(2)` gas can prevent the metal surface from corrosion.

Explanation

To solve the question "Choose the incorrect statement about corrosion on the metal surface," we will analyze each statement provided and determine which one is false.

### Step-by-Step Solution:

1. **Understanding Corrosion**:
- Corrosion is an electrochemical process where metals react with environmental factors (like moisture and oxygen) leading to deterioration. Rusting of iron is a common example.

2. **Analyzing Statement A**:
- **Statement A**: "In the corrosion of iron, reduction of oxygen while oxidation of metal takes place."
- **Analysis**: This statement is true. During rusting, iron (Fe) is oxidized to Fe²⁺, and oxygen is reduced to form hydroxide ions (OH⁻). Thus, this statement is correct.

3. **Analyzing Statement B**:
- **Statement B**: "Rusting is reduced in highly alkaline medium."
- **Analysis**: This statement is also true. Rusting is indeed reduced in highly alkaline conditions because these conditions are not favorable for the electrochemical reactions that lead to rust formation.

4. **Analyzing Statement C**:
- **Statement C**: "Magnesium can act as a sacrificial electrode."
- **Analysis**: This statement is true as well. Magnesium is more reactive than iron and can oxidize first, thus protecting iron from rusting. This is a correct statement.

5. **Analyzing Statement D**:
- **Statement D**: "CO₂ gas can prevent the metal surface from corrosion."
- **Analysis**: This statement is false. CO₂ reacts with moisture to form carbonic acid, which creates a slightly acidic environment that enhances rusting, rather than preventing it. Therefore, this statement is incorrect.

### Conclusion:
The incorrect statement about corrosion on the metal surface is **Statement D**: "CO₂ gas can prevent the metal surface from corrosion."

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