The presence of ozone in troposphere

Options

A. Protects us from the UV radiation
B. Protects us from the X-ray radiation
C. Protects us from greenhouse effect
D. generates photochemical smog

Answer

**Step-by-Step Solution:**

1. **Understanding Ozone and Its Location:**
- Ozone (O₃) is a molecule made up of three oxygen atoms. It is found in two main layers of the atmosphere: the stratosphere and the troposphere.
- In the stratosphere, ozone forms the ozone layer, which protects life on Earth by absorbing the majority of the sun's harmful ultraviolet (UV) radiation.

2. **Ozone in the Troposphere:**
- The troposphere is the lowest layer of the Earth's atmosphere, where weather occurs and where we live.
- Unlike the stratospheric ozone, tropospheric ozone is not emitted directly. It is formed by chemical reactions between volatile organic compounds (VOCs) and nitrogen oxides (NOx) in the presence of sunlight.

3. **Formation of Tropospheric Ozone:**
- When fossil fuels are burned, they release pollutants such as unburned hydrocarbons and nitrogen oxides (NO).
- These pollutants undergo a series of reactions when exposed to sunlight, leading to the formation of ozone.
- The reaction can be summarized as follows:
- NO₂ (nitrogen dioxide) absorbs sunlight and breaks down into NO (nitric oxide) and a free oxygen atom (O).
- This free oxygen atom then reacts with molecular oxygen (O₂) to form ozone (O₃).

4. **Effects of Tropospheric Ozone:**
- Tropospheric ozone is a key component of photochemical smog, which is a type of air pollution characterized by hazy conditions and reduced air quality.
- It can have harmful effects on human health, vegetation, and the environment.

5. **Conclusion:**
- The primary role of ozone in the troposphere is not to protect us from UV radiation but rather to contribute to the formation of photochemical smoke or smog.
- Therefore, the correct answer to the question is that the presence of ozone in the troposphere protects us from photochemical smoke.

**Final Answer:**
- The presence of ozone in the troposphere protects us from photochemical smoke.

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