Most ozone gas (about 90%) is located in the atmospheric layer of

Most ozone gas (about 90%) is located in the atmospheric layer of

ionosphere
troposphere
stratosphere
mesosphere
This question was previously asked in
UPSC CDS-2 – 2017
The correct option is C) stratosphere.
The vast majority of ozone gas (approximately 90%) is concentrated in the stratosphere, forming the ozone layer. This layer is crucial for absorbing most of the Sun’s harmful ultraviolet (UV) radiation. A smaller amount of ozone exists in the troposphere, where it acts as a pollutant and a greenhouse gas.
The atmosphere is divided into several layers: troposphere (lowest), stratosphere, mesosphere, thermosphere, and exosphere. The ionosphere is a region within the thermosphere and exosphere where gases are ionized by solar radiation. Ozone formation and destruction primarily occur in the stratosphere.