Ozone depletion in the stratosphere is primarily due to

Options

A. `SO_(2)`
B. `NO_(2)`
C. `NO`
D. chlorofluorocarbons

Answer

**Step-by-Step Text Solution:**

1. **Understanding Ozone Formation:**
- Ozone (O3) is formed in the stratosphere when ultraviolet (UV) radiation from the sun breaks down molecular oxygen (O2) into individual oxygen atoms (nascent oxygen).
- The reaction can be summarized as:
\[ \text{UV radiation} + \text{O}_2 \rightarrow 2 \text{O} \]
- These nascent oxygen atoms then react with other O2 molecules to form ozone:
\[ \text{O} + \text{O}_2 \rightarrow \text{O}_3 \]

2. **Identifying the Cause of Ozone Depletion:**
- Ozone depletion is primarily caused by certain pollutants that are released into the atmosphere.
- The most significant of these pollutants are chlorofluorocarbons (CFCs), which are commonly used in refrigeration, air conditioning, and aerosol propellants.

3. **Mechanism of Ozone Depletion by CFCs:**
- CFCs release chlorine atoms when they are broken down by UV radiation in the stratosphere.
- The reaction can be represented as:
\[ \text{CFC} \xrightarrow{\text{UV}} \text{Cl} + \text{other products} \]
- The chlorine atoms (Cl) act as catalysts in the destruction of ozone.
- One chlorine atom can react with ozone (O3) to produce oxygen (O2) and nascent oxygen:
\[ \text{Cl} + \text{O}_3 \rightarrow \text{ClO} + \text{O}_2 \]
- The chlorine monoxide (ClO) can further react with another oxygen atom to release the chlorine atom back into the atmosphere, allowing it to destroy more ozone:
\[ \text{ClO} + \text{O} \rightarrow \text{Cl} + \text{O}_2 \]

4. **Conclusion:**
- The continuous release of chlorine from CFCs leads to significant depletion of the ozone layer, making chlorofluorocarbons (CFCs) the primary cause of ozone depletion in the stratosphere.

**Final Answer:**
- Ozone depletion in the stratosphere is primarily due to chlorofluorocarbons (CFCs).

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