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
2023-12-22
36
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] The passage suggests that oxygen remained in the atmosphere because______.
选项
A、it was caused by outgassing
B、it was heavier than hydrogen
C、hydrogen became trapped in limestone
D、rays from the sun created equal amounts of hydrogen and oxygen
答案
B
解析
转载请注明原文地址:https://tihaiku.com/zcyy/3295744.html
相关试题推荐
Peopleofdifferentfieldscametogetherforthesamedreamofbuildingasmart
Peopleofdifferentfieldscametogetherforthesamedreamofbuildingasmart
Peopleofdifferentfieldscametogetherforthesamedreamofbuildingasmart
Peopleofdifferentfieldscametogetherforthesamedreamofbuildingasmart
Peopleofdifferentfieldscametogetherforthesamedreamofbuildingasmart
Parentingwasneverapieceofcakeinanyage,butprobablythegreatestso
Parentingwasneverapieceofcakeinanyage,butprobablythegreatestso
[originaltext]You’veprobablyheardtheslogan"savethewhales".Doyoukn
[originaltext]You’veprobablyheardtheslogan"savethewhales".Doyoukn
[originaltext]You’veprobablyheardtheslogan"savethewhales".Doyoukno
随机试题
_________anythingabouttheaccident,hewenttoworkasusual.A、NotknowB、Know
Heisnot______afool______.A、such...asbelookedB、such...ashelooksC、so
WanttoKnowYourDiseaseRisk?CheckYourExposomeA)Whenitcom
中国发展迅速的经济和相对较低的生活成本吸引着美国求职者前来。Itistherapidlygrowingeconomyandrelativelyl
31岁,G1P1,因"继发不孕2年"就诊,患者12岁月经初潮,周期28天,否认性
上市公司不得以下列方式将资金直接或间接地提供给控股股东及其他关联方使用()。
《建设工程施工专业分包合同(示范文本)》GF-2003-0213中规定属于分包人
()是历史最为悠久,也是最受到人们关注的医学伦理关系A.医社关系B.医患关系C
暂态地电压局部放电检测结果常见分析方法包括阀值分析技术、统计分析技术、横向分析技
结果导向型的绩效考评方法的基础是()A:实际产出 B:计划产出 C:
最新回复
(
0
)