When wine is exposed to air it becomes sour due to

Options

A. Bactena
B. Oxidation of `C_(2) H_(5) OH t o CH_(3) C O O H`
C. Virus
D. Formic acid formation

Answer

### Step-by-Step Solution:

1. **Understanding the Problem**: The question asks why wine becomes sour when exposed to air. We need to identify the chemical process that occurs during this exposure.

2. **Identifying the Components**: Wine primarily contains ethanol (C2H5OH) as its alcohol content. When exposed to air, certain bacteria can act on the ethanol.

3. **Role of Aerobic Bacteria**: The exposure to air allows aerobic bacteria to thrive. These bacteria facilitate the oxidation process of ethanol.

4. **Oxidation Process**:
- Initially, ethanol (C2H5OH) is oxidized to acetaldehyde (CH3CHO).
- Further oxidation of acetaldehyde leads to the formation of acetic acid (CH3COOH).

5. **Formation of Acetic Acid**: The acetic acid produced is responsible for the sour taste of the wine. This process is often referred to as aerobic fermentation.

6. **Conclusion**: Therefore, when wine is exposed to air, it becomes sour due to the oxidation of ethanol to acetic acid, resulting in a vinegar-like taste.

### Final Answer:
When wine is exposed to air, it becomes sour due to the oxidation of ethanol (C2H5OH) to acetic acid (CH3COOH) facilitated by aerobic bacteria.

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