UPSC Prelims 1998 · General Studies
Question 109: Geography
The correct sequence of different layers of the atmosphere from the surface of the Earth upwards is
AnswerThe answer is (c).
The layers of the atmosphere from the ground upwards are the troposphere (to about 12 km), the stratosphere (to about 50 km, with the ozone layer), the mesosphere (to about 80 km) and above it the thermosphere, which contains the ionosphere, a region of electrically charged layers that reflects radio waves. So the order is troposphere, stratosphere, mesosphere, ionosphere.
Why each option is right or wrong
- (a) Puts the ionosphere before the mesosphere, which is lower.
- (b) Puts the stratosphere below the troposphere and the ionosphere before the mesosphere.
- (c) Right: troposphere, stratosphere, mesosphere, ionosphere.
- (d) Puts the stratosphere below the troposphere, though the upper two are in order.
Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 1998, General Studies. UPSC's own paper isn't online; the words are from a published compilation. The paper on upsc.gov.in.