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
47
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] Which of the following items does the passage mention as necessary for both the production of oxygen by photodissociation and the production of oxygen by plants?
选项
A、Water.
B、Hydrogen.
C、Carbon dioxide.
D、Nitrogen.
答案
A
解析
转载请注明原文地址:https://tihaiku.com/zcyy/3295746.html
相关试题推荐
Therestaurantfeaturesawide-openkitchensurroundedbywoodencountersonthr
Therearemanydifferentwaysofcomparingtheeconomyofonenationwiththose
Usingextremelydifferentdecoratingschemesinadjourningroomsmayresultind
Data,largelybaseonstudents’ownreports,probablyunderestimatethescaleof
TheevidencethattheEarth’satmosphereiswarmingcontinuestoaccumulate.
[originaltext]Peoplecanbeaddictedtodifferentthings,e.g.,alcohol,dr
[originaltext]Peoplecanbeaddictedtodifferentthings,e.g.,alcohol,dr
Peopleofdifferentfieldscametogetherforthesamedreamofbuildingasmart
Peopleofdifferentfieldscametogetherforthesamedreamofbuildingasmart
Peopleofdifferentfieldscametogetherforthesamedreamofbuildingasmart
随机试题
WhatarethesecretsfromthehappiestpeopleonEarth?Somemakesense:Be【
Anewstudyfindsthatevenmildstresscanaffectyourabilitytocontroly
在设计算法时,通常应考虑以下原则:首先说设计的算法必须是(),其次应有很好的(
A.芒硝 B.藜芦 C.甘草 D.三棱 E.乌头不宜与瓜蒌同用的药物是(
成熟的标志是生理方面具有生殖能力,心理方面具有_____。
如图,三个图形的周长相等,则a:b:c是多少?() A.4:5:6 B.
善治寒凝气滞疝气疼痛的药物是()。A.橘皮B.木香C.青木香D.荔枝核E.薤白
老王今年52岁,某公司中层管理人员,月税后收入8000元,离异,与儿子小王共同生
下列属于中性点电容隔直/电阻限流装置控制电源故障现象的是()测控装置发装置异常、
党的十七大提出的发展中国特色社会主义的一大法宝是 A.改革开放B.科学发展
最新回复
(
0
)