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
23
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] According to the passage, outgassing eventually led to all of the following EXCEPT______.
选项
A、increases in the carbon dioxide content of sedimentary rocks
B、increases in the level of nitrogen
C、the formation of oxygen
D、the formation of clouds
答案
C
解析
转载请注明原文地址:https://tihaiku.com/zcyy/3910303.html
相关试题推荐
[originaltext]You’veprobablyheardtheslogan"savethewhales".Doyoukn
[originaltext]You’veprobablyheardtheslogan"savethewhales".Doyoukno
[originaltext]You’veprobablyheardtheslogan"savethewhales".Doyoukno
Thereareseveraldifferentmethodsthatcanbeusedtocreateaforecast.Th
Thereareseveraldifferentmethodsthatcanbeusedtocreateaforecast.Th
Thereareseveraldifferentmethodsthatcanbeusedtocreateaforecast.Th
Women’smindsworkdifferentlyfrommen’s.Atleast,thatiswhatmostmenar
Women’smindsworkdifferentlyfrommen’s.Atleast,thatiswhatmostmenar
Women’smindsworkdifferentlyfrommen’s.Atleast,thatiswhatmostmenar
Howwelookandhowweappeartoothersprobablyworriesusmorewhenarein
随机试题
IthasrecentlybeenannouncedthatanewrestaurantmaybebuiltInyourneighb
PoliticalchangesinEasternEuropeandtheformerSovietUnionhavereduced
对开采工艺——爆破环节描述不正确的是( )。 (1)某采矿场爆破后出现盲炮,
对于特殊或重要的建(构)筑物,必须按构成单位工程的主要分部分项工程编制,必要时结
以下关于风险的表述错误的是()。A.风险表现为给投资者带来的损失 B.风险是
王萍今年16岁,出生在广东省一个偏僻的小山村,现为北京某打工子弟学校初二学生。
某股票期权距到期日时间为2年,股票年收益率的标准差为0.16,且保持不变。则采用
甲面粉加工厂为了满足市场需求,提高生产能力,决定对原厂房进行扩建,委托具有相应资
(2019年真题)关于专业工程分包人责任和义务的说法,正确的是( )。 A
以下关于综合成本分析方法的表述中,正确的是()。A.进行分部分项工程成本分析时
最新回复
(
0
)