Name the regions of the atmosphere where oxygen and ozone play key role ?

Question

Accepted Answer

Option 2, which states that the regions of the atmosphere where oxygen and ozone play key roles are the Troposphere and Stratosphere, is correct. Here's why:

1. **Troposphere**: This is the lowest layer of Earth's atmosphere, extending from the surface up to about 8-15 kilometers (5-9 miles) high. Oxygen is crucial in the troposphere because it is the layer where all weather occurs and where most of the atmospheric gases, including oxygen, are found. Oxygen is essential for life on Earth, as it is required for respiration by most living organisms.

2. **Stratosphere**: This layer lies above the troposphere, extending from about 15 to 50 kilometers (9 to 31 miles) above the Earth's surface. The stratosphere is where the ozone layer is located. Ozone plays a critical role in this region by absorbing the majority of the Sun's harmful ultraviolet (UV) radiation, protecting living organisms on Earth from potential damage. The presence of ozone in the stratosphere is vital for maintaining the balance of life on Earth.

Now, let's explain why the other options are incorrect:

1. **Option 1: Mesosphere, Stratosphere** - While the stratosphere is correctly identified as a region where ozone plays a key role, the mesosphere is not primarily associated with significant roles for oxygen or ozone. The mesosphere is above the stratosphere and is known for being the layer where meteors burn up upon entering Earth's atmosphere, but it does not have a significant concentration of ozone or a critical role for oxygen.

2. **Option 3: Ionosphere, Mesosphere** - The ionosphere is a part of the thermosphere and is known for its role in radio wave propagation and auroras, not for oxygen or ozone. Similarly, as mentioned, the mesosphere does not have a significant role for oxygen or ozone.

3. **Option 4: Exosphere, Thermosphere** - The exosphere is the outermost layer of Earth's atmosphere, where atmospheric particles are sparse, and it does not play a significant role in oxygen or ozone presence. The thermosphere, while containing the ionosphere, is more associated with high-energy phenomena like auroras and does not have a significant concentration of ozone or a critical role for oxygen.

In conclusion, Option 2 is the correct answer because the troposphere is where oxygen is most abundant and essential for life, and the stratosphere is where the ozone layer is located, playing a crucial role in protecting Earth from UV radiation.