首页
登录
职称英语
The atmosphere that originally surrounded Earth was probably much different
The atmosphere that originally surrounded Earth was probably much different
游客
2025-01-13
9
管理
问题
The atmosphere that originally surrounded Earth was probably much different from the air we breathe today. Earth’s first atmosphere(some 4.6 billion years ago)was most likely hydrogen and helium—the two most abundant gasses found in the universe—as well as hydrogen compounds, such as methane and ammonia, Most scientists feel that this early atmosphere escaped into space from the Earth’s hot surface.
A second, more dense atmosphere, however, gradually enveloped Earth as gasses from molten rocks within its hot interior escaped through volcanoes and steam vents. We assume that volcanoes spewed out the same gasses then as they do today: mostly water vapor(about 80 percent), carbon dioxide(about 10 percent), and up to a few 10 percent nitrogen. These same gasses probably created Earth’s second atmosphere.
As millions of years passed, the constant outpouring of gasses from the hot interior—known as outgassing— provided a rich supply of water vapor, which formed into clouds. Rain fell upon Earth for many thousands or years, forming the rivers, lakes, and oceans of the world. During this time, large amounts of carbon dioxide were dissolved in the oceans. Through chemical and biological processes, much of the carbon dioxide became locked up in carbon sedimentary rocks, such as limestone. With much of the water vapor already condensed into water and the concentration of carbon dioxide dwindling, the atmosphere gradually became rich nitrogen.
It appears that oxygen, the second most abundant gas in today’s atmosphere, probably began an extremely slow increase in concentration as energetic rays from the sun split water vapor into hydrogen and oxygen during a process called photodissociation. The hydrogen, being lighter, probably rose and escaped into space, while the oxygen remained in the atmosphere.
This slow increase in oxygen may have provided enough of this gas for primitive plants to evolve, perhaps two to three billion years ago. Or the plants may have evolved in an almost oxygen-free(anaerobic)environment. At any rate, plant growth greatly enriched our atmosphere with oxygen. The reason for this enrichment is that plants, in the presence of sunlight, process carbon dioxide and water to produce oxygen. [br] What is the main idea of the passage?
选项
A、The original atmosphere on Earth was unstable.
B、The atmosphere on Earth has changed over time.
C、Hot underground gasses created clouds, which formed the Earth’s atmosphere.
D、Plant growth depended on oxygen in the Earth’s atmosphere.
答案
B
解析
转载请注明原文地址:https://tihaiku.com/zcyy/3910302.html
相关试题推荐
Parentingwasneverapieceofcakeinanyage,butprobablythegreatestso
Parentingwasneverapieceofcakeinanyage,butprobablythegreatestso
Parentingwasneverapieceofcakeinanyage,butprobablythegreatestso
Parentingwasneverapieceofcakeinanyage,butprobablythegreatestso
[originaltext]You’veprobablyheardtheslogan"savethewhales".Doyoukn
[originaltext]You’veprobablyheardtheslogan"savethewhales".Doyoukno
[originaltext]You’veprobablyheardtheslogan"savethewhales".Doyoukno
Thereareseveraldifferentmethodsthatcanbeusedtocreateaforecast.Th
Thereareseveraldifferentmethodsthatcanbeusedtocreateaforecast.Th
Thereareseveraldifferentmethodsthatcanbeusedtocreateaforecast.Th
随机试题
Popstarstodayenjoyastyleoflivingwhichwasoncetheprerogativeonly
PassageFour[br]What’stheauthor’sattitudeinthispassage?Objective.根据全文可以看
所谓“泛娱乐化”现象,指的是一般以消费主义、享乐主义为核心,以现代媒介(电视、喜
脊髓半侧损害的感觉障碍为A.受损平面以下的同侧痛、温觉障碍,对侧深感觉障碍 B
某女,53岁。胸胁胀满,眩晕心悸,短气而咳,舌苔白滑,脉弦滑。治宜选用A.苓桂术
阅读材料,并回答问题。 材料 ①1785年,科学家卡文迪许在测定空气组成时,
卡介菌初种年龄是A.生后2~3天 B.8个月以上 C.1岁以上 D.2个月
2020年1-12月份,全市固定资产投资3815.36亿元,同比增长6.1%。房
出让合同等未约定土地使用权期间届满后需要无偿收回土地使用权及地上建筑物。
使血清白蛋白(pI为4.7)带正电荷的溶液pH值是( )。A.4.0 B.5
最新回复
(
0
)