CTET 2 Social and Science Dec 2018 Paper

Exosphere helps in the transmission of radio waves. It is the outermost layer of the earth's atmosphere. Mesosphere is the layer of the earth's atmosphere that is directly above the stratosphere and directly below the thermosphere.
Thermosphere is the layer of the earth's atmosphere directly above the mesosphere and below the exosphere. Stratosphere is the second major layer of earth's atmosphere lying above the troposphere and below the mesosphere.