The correct answer is 97% because Earth’s gravity pulls the majority of atmospheric gases closer to the surface. As you ascend, air pressure and density drop significantly. By the time you reach 29 kilometers, almost all the air mass is beneath you. This lower region contains the vast majority of the molecules necessary for life and weather phenomena on Earth. ANSWER: (B) 97%
What percentage of the Earth’s atmosphere is found up to an altitude of 29 km? (A) 76% (B) 97% (C) 29% (D) 57%
Share
Approximately 97% of the Earth’s atmosphere is concentrated within the first 29 kilometers of the surface. This high density is a direct result of gravitational attraction, which packs gas molecules tightly at lower altitudes. Because air is compressible, the weight of the overhead atmosphere compresses the lower layers, making the air near the surface much thicker than the air in the upper reaches. This thin but dense layer encompasses the troposphere and part of the stratosphere, containing nearly all the moisture and oxygen required for terrestrial life. Beyond this point, the atmosphere becomes extremely rarefied and essentially fades into space.
Master your competitive exams with TA Exam! Practice mock tests, review mistakes and track your accuracy.
Download now:
Android: https://play.google.com/store/apps/details?id=com.ta.exam
iOS: https://apps.apple.com/app/id6759824444