A major class of organic halides that are thought to pose a threat to stratospheric ozone are _________.

Answer

To answer the question regarding the major class of organic halides that pose a threat to stratospheric ozone, we can follow these steps:

### Step-by-Step Solution:

1. **Identify Organic Halides**:
- Organic halides are compounds that contain carbon (C) and at least one halogen atom (F, Cl, Br, I). They are often used in various industrial applications.

2. **Understand the Threat to Ozone**:
- The stratospheric ozone layer is crucial for protecting the Earth from harmful ultraviolet (UV) radiation. Certain organic halides can deplete this ozone layer.

3. **Recognize Key Examples**:
- Among the various classes of organic halides, chlorofluorocarbons (CFCs) are well-known for their damaging effects on the ozone layer.

4. **Define CFCs**:
- CFCs, or chlorofluorocarbons, are a specific type of organic halide that contains chlorine, fluorine, and carbon. They were commonly used in refrigeration, aerosol propellants, and foam-blowing agents.

5. **Provide an Example**:
- A common example of a CFC is CF2Cl2, also known as dichlorodifluoromethane or Freon-12. This compound has two fluorine atoms and two chlorine atoms attached to a carbon atom.

6. **Conclude the Answer**:
- Therefore, the major class of organic halides that are thought to pose a threat to stratospheric ozone is **CFCs (chlorofluorocarbons)**.

### Final Answer:
A major class of organic halides that are thought to pose a threat to stratospheric ozone are **CFCs (chlorofluorocarbons)**.

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