首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
About a century ago, the Swedish physical scientist Arrhenius proposed a low of classical chemistry that relates chemical reacti
About a century ago, the Swedish physical scientist Arrhenius proposed a low of classical chemistry that relates chemical reacti
admin
2015-01-31
45
问题
About a century ago, the Swedish physical scientist Arrhenius proposed a low of classical chemistry that relates chemical reaction rate to temperature. According to his equation, chemical reactions are increasingly unlikely to occur as temperature approaches absolute zero, and at absolute zero, reactions stop. However, recent experiment evidence reveals that although the Arrhenius equation is generally accurate in describing the kind of chemical reaction that occurs at relatively high temperature, at temperatures closer to zero a quantum-mechanical effect known as tunneling comes into play; this effect accounts for chemical reactions that are forbidden by me principles of classical chemistry. Specifically, entire molecules can tunnel through the barriers of repulsive forces from other molecules and chemically react even though these molecules do not have sufficient energy, according to classical chemistry, to overcome the repulsive barrier.
The rate of any chemical reaction, regardless of the temperature at which it takes place, usually depends on a very important characteristic known as its activation energy. Any molecule can be imagined to reside at the bottom of a so-called potential well of energy. A chemical reaction corresponds to the transition of a molecule from the bottom of one potential well to the bottom of another. In classical chemistry, such a transition can be accomplished only by going over the potential barrier between the well, the height of which remains constant and is called the activation energy of the reaction. In tunneling, the reactings molecules tunnel from the bottom of one to the bottom of another well without having to rise over the barrier between the two wells. Recently researchers have developed the concept of tunneling temperature: the temperature below which tunneling transitions greatly outnumber Arrhenius transitions, and classical mechanics gives way to its quantum counterpart.
This tunneling phenomenon at very low temperatures suggested my hypothesis about a cold prehistory of life: formation of rather complex organic molecules in the deep cold of outer space, where temperatures usually reach only a few degrees Kelvin. Cosmic rays might trigger the synthesis of simple molecules, such as interstellar formaldehyde, in dark clouds of interstellar dust. Afterward complex organic molecules would be formed, slowly but surely, by means of tunneling. After I offered my hypothesis, Hoyle and Wickramashinghe argued that molecules of interstellar formaldehyde have indeed evolved into stable polysaccharides such as cellulose and starch. Their conclusions, although strongly disputed, have generated excitement among investigators such as myself who are proposing that the galactic clouds are the places where the prebiological evolution of compounds necessary to life occurred.
Which of the following best describes the organization of the first two paragraphs of the passage?
选项
A、The author cites a basic principle of classical chemistry and then describes the research from which that principle was developed.
B、The author presents the fundamental rules of classical chemistry in order to introduce an explanation of a specific chemical reaction.
C、The author describes the role of heat in chemical reactions and then offers a detailed explanation of its function.
D、The author presents a law of classical chemistry in order to introduce a kind of chemical reaction that differs from it and then explains the essential difference between the two.
答案
D
解析
推断题。根据文章前两段内容可知,第一段首先论述了经典化学定理,然后介绍了隧道效应,在第二段中对比经典化学定理和隧道效应,说明二者使用的温度界限不同。和选项D的顺序一致,所以答案选D。
转载请注明原文地址:https://kaotiyun.com/show/ZGh7777K
0
大学英语六级
相关试题推荐
A、TheirBBSwasnotasgoodaswhattheyhadthoughtbefore.B、Theirprogressinthewebsite-designwashinderedforlackoffun
A、It’satraditionalEuropeanfestival.B、ItfallsonthedaybeforeEaster.C、Thetraditionalcelebrationisdecoratingeggs.D
NewtechnologylinkstheworldasneverbeforeOurplanethas【B1】______.It’snowa"globalvillage"wherecountriesareonlyse
NewtechnologylinkstheworldasneverbeforeOurplanethas【B1】______.It’snowa"globalvillage"wherecountriesareonlyse
A、Midnineteenthcentury.B、Latenineteenthcentury.C、Mideighteenthcentury.D、Lateeighteenthcentury.A短文谈到,美国有很多中国餐馆,超市里也卖中
A、Everyonewouldbuildashipmodeltocelebratetheday.B、Everyonewasaskedtowearclothesofthelastcenturyonthatday.
Thelongestbullruninacenturyofart-markethistoryendedonadramaticnotewithasaleof56worksbyDamienHirst,"Beaut
Britishscientistsarebreedinganewgenerationofriceplantsthatwillbeabletogrowinsoilcontainingsaltwater.Theirw
Britishscientistsarebreedinganewgenerationofriceplantsthatwillbeabletogrowinsoilcontainingsaltwater.Theirw
Britishscientistsarebreedinganewgenerationofriceplantsthatwillbeabletogrowinsoilcontainingsaltwater.Theirw
随机试题
已知,则X=_______.
患者女性,71岁,糖尿病史15年,晨练时不慎摔倒,当时无明显不适,摔后3小时突然腹部剧烈疼痛,血压150/120mmHg。超声检查脐水平腹主动脉左旁可见类圆形厚壁无回声区如果我们将取样容积置于细窄的起始部,可探及到的血流频谱为
夹套管道的内管应用干燥无油压缩空气进行系统吹扫,气体流速不应小于()m/s,在管子出口处放置白布进行检查,以无铁锈、脏物为合格。
已知某企业本年“营业收入”为280万元,“营业成本”为160万元,“管理费用”为60万元,“营业外支出”为40万元。假设不考虑其他因素,该企业本年营业利润为()万元。
依据仲裁协议订立的时间和形式的不同,仲裁协议()。
五斗米道组织在()时期得到完善。
“吃熟食,喝开水,勤洗手,晒衣被”主要是为了预防()
一、注意事项1.申论考试,与传统作文考试不同,是对分析驾驭材料的能力与对表达能力并重的考试。2.作答参考时,阅读资料40分钟,作答110分钟。3.仔细阅读给定的资料,按照后面提出的“申论要求”依次作答。二、给定资料材料1
根据域名代码规定,表示政府部门网站的域名代码是()。
MostbanksintheUSopenat9:00or10:00andclosebetween3:00and5:00,butstayopenlateronFridays,andsomebankshave
最新回复
(
0
)