Reason (R) : Ultraviolet radiations are absorbed in the upper atmosphere.
Choose the correct answer :
Evaluating Assertion (A): Upper Atmosphere Shields Life
The assertion states that the upper atmosphere shields life on Earth. This is factually correct. The Earth's atmosphere, particularly layers like the stratosphere containing the ozone layer, acts as a protective barrier against harmful solar radiation.
Evaluating Reason (R): UV Radiation Absorption
The reason given is that ultraviolet (UV) radiations are absorbed in the upper atmosphere. This statement is also factually correct. The ozone layer ($O_3$) within the stratosphere absorbs the majority of the Sun's harmful ultraviolet radiation, preventing it from reaching the Earth's surface.
Analyzing the Relationship Between Assertion and Reason
While the absorption of UV radiation (Reason R) is a crucial part of how the upper atmosphere shields life (Assertion A), it might not be considered the sole or complete explanation. The upper atmosphere provides shielding through various mechanisms, including:
- Absorption of harmful UV radiation by the ozone layer.
- Absorption of other high-energy radiation (like X-rays and gamma rays) in the thermosphere and ionosphere.
- Protection from meteoroids burning up upon entry.
- Regulation of temperature.
Therefore, although Reason (R) is true and directly contributes to Assertion (A), it doesn't encompass the entirety of the shielding effect provided by the upper atmosphere. Hence, (R) is not the complete or sole correct explanation for (A).
Determining the Correct Option
Based on the analysis:
- Assertion (A) is true.
- Reason (R) is true.
- Reason (R) is not the sole or complete explanation for Assertion (A).
This corresponds to Option 2.
Important Questions from Atmosphere
In the cities of our country, which among the following atmospheric gases are normally considered in calculating the value of Air Quality Index?
1. Carbon dioxide
2. Carbon monoxide
3. Nitrogen dioxide
4. Sulfur dioxide
5. Methane
Select the correct answer using the code given below.
A layer in the Earth's atmosphere called Ionosphere facilitates radio communication. Why?
1) The presence of ozone causes the reflection of radio waves to Earth.
2) Radio waves have a very long wavelength.
Which of the statements given above is/are correct?
The jet aircrafts fly very easily and smoothly in the lower stratosphere. What could be the appropriate explanation?
1) There are no clouds or water vapour in the lower stratosphere.
2) There are no vertical winds in the lower stratosphere.
Which of the statements given above is/are correct in this context?
The increasing amount of carbon dioxide in the air is slowly raising the temperature of the atmosphere, because it absorbs
Which one of the following is associated with the issue of control and phasing out of the use of ozone-depleting substances?
