Ozone present in stratosphere comes from

Options

A. Photosynthesis activity from earth
B. Reaction between nitrogen oxides and `O_(2)`
C. Photochemical interactions of oxygen molecules
D. Microbial decay on earth.

Answer

**Step-by-Step Solution:**

1. **Understanding Ozone**: Ozone is a molecule composed of three oxygen atoms, represented by the chemical formula O3. It is found in the stratosphere and plays a crucial role in absorbing harmful ultraviolet (UV) radiation from the sun.

2. **Location of Ozone Formation**: Ozone is primarily formed in the stratosphere, which is the second layer of the atmosphere above the troposphere. The stratosphere is where the ozone layer is located.

3. **Process of Ozone Formation**:
- When UV light from the sun reaches the stratosphere, it provides energy that breaks down oxygen molecules (O2) into individual oxygen atoms (O).
- This process is known as a photochemical reaction, where light energy is used to drive a chemical reaction.
- The free oxygen atoms can then react with other oxygen molecules (O2) to form ozone (O3). Specifically, one oxygen atom combines with an O2 molecule to produce one ozone molecule.

4. **Analyzing the Options**:
- **Option A: Photosynthetic activity from Earth**: This is incorrect because photosynthesis primarily produces oxygen (O2) but does not directly create ozone.
- **Option B: Reaction between nitrogen oxides and oxygen**: This is also incorrect as this reaction does not produce ozone.
- **Option C: Photochemical interactions of oxygen molecules**: This is the correct answer, as it accurately describes the process by which ozone is formed in the stratosphere through photochemical reactions.
- **Option D: Microbial decay on Earth**: This is incorrect because microbial decay typically produces gases like methane or carbon dioxide, not ozone.

5. **Conclusion**: The correct answer to the question "Ozone present in stratosphere comes from" is **C: Photochemical interactions of oxygen molecules**.

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