Which one is responsible for depletion of ozone layer in the upper strata of the atmosphere?

Options

A. Chlorine
B. Ferrocenes
C. Fullerenes
D. Freons

Answer

### Step-by-Step Solution:

1. **Identify the Question**: The question asks which substance is responsible for the depletion of the ozone layer in the upper strata of the atmosphere.

2. **Understand Ozone Layer**: The ozone layer is a region of Earth's stratosphere that contains a high concentration of ozone (O3) and protects the Earth from harmful ultraviolet (UV) radiation.

3. **Identify Potential Culprits**: Various substances can deplete the ozone layer, but the most notable ones are chlorofluorocarbons (CFCs), commonly referred to as Freons.

4. **Explain the Stability of CFCs**: CFCs are stable compounds that do not break down easily in the lower atmosphere. This stability allows them to persist and eventually rise to the stratosphere.

5. **Reaction with Ozone**: Once CFCs reach the upper atmosphere, they are broken down by UV radiation, releasing chlorine atoms. These chlorine atoms react with ozone (O3) molecules.

6. **Formation of Oxygen**: The reaction between chlorine and ozone results in the conversion of ozone into oxygen (O2), which is a stable molecule. This reaction can be summarized as:
\[ \text{Cl} + \text{O}_3 \rightarrow \text{ClO} + \text{O}_2 \]
The chlorine monoxide (ClO) can further react with other ozone molecules, leading to further depletion.

7. **Conclusion**: The continuous reaction of CFCs with ozone leads to a significant reduction in the ozone layer, resulting in its depletion.

8. **Final Answer**: Therefore, the substance responsible for the depletion of the ozone layer in the upper strata of the atmosphere is **Freons (CFCs)**.