首页
登录
职称英语
About a century ago, the Swedish physical scientist Arrhenius proposed a low
About a century ago, the Swedish physical scientist Arrhenius proposed a low
游客
2025-01-03
36
管理
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 the 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. Some 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 remain constant and is called the activation energy of the reaction. In tunneling, the reacting molecules tunnel from the bottom of one to the bottom of another well without having to rise over the harrier 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 hut 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. [br] The author’s attitude toward the theory of a cold prehistory of life can best be described as ______.
选项
A、neutral
B、skeptical
C、mildly positive
D、very supportive
答案
C
解析
有点肯定。因为证实了作者之假设。
转载请注明原文地址:https://tihaiku.com/zcyy/3896889.html
相关试题推荐
Acenturyago,acutorevenadecayedtoothwerecausesforalarm,astheyc
Acenturyago,acutorevenadecayedtoothwerecausesforalarm,astheyc
JonasFrisenhadhiseurekamomentin1997.Backthen,scientistssuspectedt
JonasFrisenhadhiseurekamomentin1997.Backthen,scientistssuspectedt
JonasFrisenhadhiseurekamomentin1997.Backthen,scientistssuspectedt
In17th-centuryNewEngland,almosteveryonebelievedinwitches.Struggling
In17th-centuryNewEngland,almosteveryonebelievedinwitches.Struggling
In17th-centuryNewEngland,almosteveryonebelievedinwitches.Struggling
______isproposedbyM.A.K.Halliday.A、Systemic-functionalgrammarB、Universal
Thedistinctionbetweencompetenceandperformanceisproposedby______.A、Sauss
随机试题
Hawaii’snativeminorityisdemandingagreaterdegreeofsovereigntyoveri
农业统计是反映农业再生产经营现状和过程的统计,包括种植业、林业、牧业和渔业等4个
代理业务属于商业银行的( )。A.中间业务 B.负债业务 C.表内业务
可谓是后世甘温除热治法先声的方剂是A.大建中汤 B.小建中汤 C.黄芪建中汤
影响微囊药物释放速率的因素说法错误的是A.微囊的粒径越小释药速率越大B.囊壁越厚
《变电运维管理规定第21分册端子箱及检修电源箱运维细则》:端子箱及检修电源箱体及
A.球被顶出,说明力可以改变物体的运动状态 B.顶出去的球在上升过程中,受到平
下列何药可翻转肾上腺素的升压效应?( )A.酚妥拉明 B.阿替洛尔 C.可
项目前期策划成果质量评审的外部评审包括()。A.项目团队组织的评审 B.项目经
对某社区进行糖尿病健康促进规划的结局评价应评估糖尿病患者A.饮食态度的改变 B
最新回复
(
0
)