Question

Which of the following is the lowest layer of the atmosphere?
A. Stratosphere
B. Troposphere
C. Thermosphere
D. Exosphere

Answer 1

Hint: Earth has an atmosphere above its crust and sea level. The earth’s atmosphere is made up of five different layers. Each layer has unique features. The layer in which we live is called the troposphere.

Complete step-by-step answer:
The atmosphere of Earth is the layers of gases, which surround the planet. These layers play a major role in the survival of life on Earth as it shields the planet from various radiations and debris that try to enter the Earth. The atmosphere is divided into five different layers based on its height and its specific traits. As we move up from the ground level, these layers are the troposphere, stratosphere, mesosphere, thermosphere and exosphere.
Troposphere
The troposphere is the lowest layer of the atmosphere. It starts at the sea level and extends upward to 10 km. above the sea level. Almost all life exists in this layer. Most of the clouds and weather exist here.
Stratosphere
The stratosphere is the next layer and extends to about 50 km above the sea level. The ozone layer is found in the stratosphere and shields the Earth from harmful UV rays of the sun.
Mesosphere
Above the Stratosphere is the mesosphere which extends to about 85 above the sea level. Most meteors and space debris burn up in this layer as they try to enter the Earth. The air in this layer is too thin to be breathable and temperature is the coldest at the top of this layer.
Thermosphere
Above the mesosphere is the Thermosphere which extend to anywhere between 500-1000 km above the sea level. High energy radiations are absorbed in this layer. The air is too thin in this layer. The aurora, i.e: The northern and southern lights, occur in this layer.
Exosphere
The final Layer of the atmosphere is the exosphere. The air is thinnest here and could be seen to be leaking out into outer space. There is no set boundary for this layer. Beyond this layer the interplanetary outer space begins.
Hence, the correct option is B.

Note: Note that the meaning of air being thin is about the density of the air. As we know due to the gravitational force from earth, the denser substance settles down. Therefore, the layer of the atmosphere that is lower has higher density than the density of the layer above. Low density implies lack of oxygen in the air. Hence, it is difficult to breathe at higher heights.