Layer that contains the ozone layer?

• A. Troposphere
• B. Stratosphere
• C. Mesosphere
• D. Thermosphere

Answer: (B)

The ozone layer is located in the stratosphere. This part of the atmosphere sits above the troposphere and below the mesosphere, roughly 10–30 km above Earth’s surface (the exact height varies by location and season). Ultraviolet radiation from the sun splits oxygen molecules, and in the stratosphere the resulting oxygen atoms can join with O2 to form ozone (O3). The stratosphere’s relatively stable air allows ozone to accumulate, and the ozone itself absorbs UV radiation, warming the surrounding air and creating a temperature rise with height that helps keep the layer intact. Most atmospheric ozone—about 90%—is found there, serving as a protective shield against harmful UV radiation. In contrast, ozone in the troposphere is a pollutant that can harm air quality, while the higher layers are much thinner and follow different chemical dynamics.