Question

At what height over the earth does the ozone layer exist?
A. 200 km
B. 150 km
C. 100 km
D. 25 km

Answer 1

The earth’s atmosphere has a series of layers, each with its own unique characteristics. These layers are called the troposphere, stratosphere , mesosphere, thermosphere and exosphere, rising upward from the ground level. In the realm of interplanetary space, the exosphere steadily fades away.

Complete answer:
The second layer of the Earth’s atmosphere is called the stratosphere. The stratosphere rises to about 25 km above ground from the top of the troposphere. The stratosphere, unlike the troposphere, actually gets warmer the higher one goes. The pattern of temperatures rising with altitude means that the turbulence and updrafts that arise in the troposphere are below neglect in the air of the stratosphere. In the lower stratosphere, commercial passenger jets travel, partially because this less-turbulent layer offers a smoother flight. The jet stream flows close to the boundary of the troposphere and the stratosphere. Inside the stratosphere, the notorious ozone layer is located. In this layer, the ozone molecules absorb ultraviolet (UV) high-energy light from the sun, turning the UV energy into heat energy. The ozone present in the stratosphere prevents humans from skin cancer and other health damages caused by absorbing dangerous UV radiation. However, chemicals (like halons and CFCs/freons) formerly used in refrigerators, spray cans and fire extinguishers have decreased the amount of ozone in the stratosphere, majorly contributing to the so-called "Antarctic ozone hole," at polar latitudes.
From the above discussion, we can say that the correct answer is option D.

Note: Thermosphere is labelled as the "hottest layer" of the atmosphere, as it contains the warmest temperatures in the atmosphere. The temperature rises with height, until the approximate top of the thermosphere at 500 km.