5Dec19 FS Q34
- Option : D
- Explanation : In the stratosphere, ozone molecules absorb ultraviolet radiation from the Sun and shield Earth from dangerous rays. But in the troposphere, near ground-level, ozone molecules are both air pollutants, threatening the health of living things, and greenhouse gases, trapping heat and contributing to climate change. The highest ozone concentrations of the year generally occur during summer, when sunlight is most intense. Ozone concentrations consequently reach maximum shortly after the peak in vehicle traffic, about noon or soon thereafter. So, (A) is false. However, (R) is true; the atmosphere is most unstable during the afternoon because heating of the earth's surface heats up the air just above it which expands and its components get diluted.
