Ozone hole is caused by

Options

A. Acetylene
B. Ethylene
C. Chloroflurocarbons
D. Methane

Answer

### Step-by-Step Solution:

1. **Understanding the Ozone Hole**:
- The ozone hole refers to the depletion of the ozone layer, which is located in the stratosphere, a layer of the Earth's atmosphere.

2. **Identifying the Cause**:
- The primary cause of the ozone hole is the release of certain chemicals into the atmosphere. Among the options provided (acetylene, ethylene, chlorofluorocarbons, and amethyl), we need to identify which one is responsible for ozone depletion.

3. **Role of Chlorofluorocarbons (CFCs)**:
- Chlorofluorocarbons (CFCs) are a group of man-made compounds that contain carbon, chlorine, and fluorine. They are known for their role in ozone depletion.

4. **Mechanism of Ozone Depletion**:
- When CFCs are released into the atmosphere, they eventually reach the stratosphere. There, they are broken down by ultraviolet (UV) radiation, releasing reactive chlorine atoms.

5. **Reaction with Ozone**:
- The reactive chlorine atoms released from CFCs react with ozone (O3) molecules in the stratosphere. This reaction leads to the conversion of ozone into diatomic oxygen (O2), thereby depleting the ozone layer.

6. **Impact on Ozone Concentration**:
- The depletion of ozone results in a significant reduction in its concentration, often measured to be less than 220 Dobson Units, particularly over Antarctica, where the phenomenon is most pronounced.

7. **Conclusion**:
- Therefore, the ozone hole is primarily caused by chlorofluorocarbons (CFCs).

### Final Answer:
The ozone hole is caused by chlorofluorocarbons (CFCs).

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