Read the following statements carefully and select the correct ones
I.UV rays are essential for the production as well as degradation of ozone gas
II.Ozone present in ionosphere acts as a shield absorbing UV radiation coming from the sun
III.One fourth of the incoming solar radiation is reflected by the atmospheric gases and clouds and only half of the incoming solar radiation falls on the earth surface heating it of this only a small portion is reflected back

Options

A. I and II
B. I and III
C. II and III
D. all of these

Answer

To determine which of the statements are correct, let's analyze each one step by step.

### Step 1: Analyze Statement I
**Statement I:** "UV rays are essential for the production as well as degradation of ozone gas."

- **Explanation:** UV rays from the sun play a crucial role in both the formation and breakdown of ozone (O3). When UV light interacts with ozone, it can break it down into oxygen molecules (O2) and free oxygen atoms (O). These free oxygen atoms can then react with other oxygen molecules to form ozone again. Thus, this statement is **correct**.

### Step 2: Analyze Statement II
**Statement II:** "Ozone present in ionosphere acts as a shield absorbing UV radiation coming from the sun."

- **Explanation:** Ozone is primarily found in the stratosphere, not the ionosphere. The stratospheric ozone layer does absorb a significant amount of UV radiation, protecting the Earth from harmful UV rays. Therefore, this statement is **incorrect** because it incorrectly states the location of ozone.

### Step 3: Analyze Statement III
**Statement III:** "One fourth of the incoming solar radiation is reflected by the atmospheric gases and clouds and only half of the incoming solar radiation falls on the Earth's surface heating it; of this, only a small portion is reflected back."

- **Explanation:** It is true that a significant portion of solar radiation is reflected by atmospheric gases and clouds, and about half of the incoming solar radiation reaches the Earth's surface. The statement correctly describes the reflection and absorption of solar radiation. Thus, this statement is **correct**.

### Conclusion
Based on the analysis:
- Statement I is **correct**.
- Statement II is **incorrect**.
- Statement III is **correct**.

### Final Answer:
The correct statements are I and III.

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