Question

The most important layer of the atmosphere is ____________.
a.Troposphere
b.Thermosphere
c.Mesosphere
d.Stratosphere

Answer 1

Hint: An atmosphere is a layer or a set of layers of gases surrounding a planet that is held in position by the gravity of that body. There are a total 5 layers in the atmosphere.

Complete Step by Step Answer:
The atmosphere is constituted of layers based on temperature. These layers are the troposphere, stratosphere, mesosphere, thermosphere and exosphere.

Looking at the above options:

Option a: Troposphere is regarded as the most important layer of atmosphere. It is the lowermost layer of the atmosphere and contains 75% of all air in the atmosphere. Most clouds occur in this layer because 99% of the water vapour in the atmosphere is found here. Temperature and air pressure drop as you go higher in the troposphere. This option is correct.

Option b: Thermosphere lies above the mesosphere and this is a region where the temperature increases as one goes higher. The increase in temperature is caused due to the absorption of energetic ultraviolet and X-Ray radiation from the sun. The aurora, the Northern Lights and Southern Lights, occur in the thermosphere. This option is incorrect.

Option c: Mesosphere extends to a height of about 85 km from the ground. The temperature grows colder as one rises up through the mesosphere. The coldest parts of the atmosphere are located in this layer. This option is not correct.

Option d: The stratosphere expands from the top of the troposphere to about 50 km above the ground. The ozone layer lies here and the ozone molecules in this layer absorb high-energy ultraviolet rays. Due to this, it gets warmer when one goes higher in the stratosphere. This option is incorrect.

Hence, the correct answer is option 'a'.

Note: The most abundant gas in the atmosphere is nitrogen, followed by oxygen and Argon. The main mechanism for which methane is removed from the earth's atmosphere is by oxidation within the troposphere by the hydroxyl radical.