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
自考
Learn about Noble Gases(惰性气体) 1 Have you ever ridden on a balloon? Many tourist spots offer balloon rides in order for peopl
Learn about Noble Gases(惰性气体) 1 Have you ever ridden on a balloon? Many tourist spots offer balloon rides in order for peopl
admin
2014-02-27
54
问题
Learn about Noble Gases(惰性气体)
1 Have you ever ridden on a balloon? Many tourist spots offer balloon rides in order for people to see the beauty of a place from above. A balloon contains a noble gas called helium. Formerly, balloons contained hydrogen but hydrogen is very flammable and dangerous when uncontrolled. Therefore, people shifted to helium, which is safer. Helium is safe because it has the properties of the noble gases.
2 People once believed that noble gases couldn’ t chemically react at all. For this reason, they were called inert gases. They were also clustered under Group 0 in the old periodic table because scientists believed that the gases have zero valence electrons in their outer shell. This was later proven to be untrue when some noble gas compounds were discovered.
3 The gases are elements, which share similar properties. These properties include being monatomic, colorless, odorless, being able to conduct electricity, and having low chemical reactivity. Noble gases include Helium, Neon, Argon, Krypton, Xenon and Radon. These are all found in Group 18, in the rightmost column of the periodic table. If you look at the periodic table, you will notice that these elements are the only ones, which do not have a charge. Helium has the lowest molecular(分子的)weight while Radon is the heaviest.
4 Remember that chemical reactions occur because atoms have "valence" electrons, which are electrons in their outer shell. When the outer shell is "unfilled" or the required number of electrons is not yet complete, the atom is more reactive. Noble gases have a full outer shell, meaning that they have complete electrons in their outer shell. This complete number varies. For instance, the outer shell of Helium has 2 valence electrons while the outer shell of Xenon has 8 electrons. Nowadays, there remains to be a few noble gases because of the inherent low chemical reactivity of these said gases.
5 Because of their properties, noble gases have many important applications. They are widely used in recreation, medicine and industries. For instance, Liquid Helium is used for superconducting magnets(磁体). These magnets are very important in physics and medicine. When a doctor suspects that a person’ s brain has been damaged, he might request for Magnetic Resonance Imaging(MRI). MRI allows the doctor to "see" the brain, without operating on the patient.
A . What are the applications of noble gas?
B. Safe is a property of the noble gas .
C. What are noble gases?
D. What cause the low chemical reactivity of noble gases?
E. How were noble gases understood in the past?
F. What is the periodic table?
Paragraph5______
选项
答案
A
解析
第5段第1句“Because of their properties,noble gases have many important applications”就讲明主旨:由于其特性,惰性气体有很多重要应用。所以A选项What are the applications ofnoble gases?“惰性气体的应用”正确。
转载请注明原文地址:https://www.kaotiyun.com/show/EE8R777K
本试题收录于:
英语(二)题库公共课分类
0
英语(二)
公共课
相关试题推荐
Anunderstandingofman’seffectonthebalanceofnatureiscrucial(关键的)tobeingabletofindtheappropriateremedialaction.
Towriteuphisnovel,Johnislookingforanenvironmentfree______outsidedistraction.
Peopleandanimalsaredifferent______theirreactionstodrugsandintheway______theirbodieswork.
Ourlikesand______areallrelatedtosocialcontextsandlearningexperiences.
TheRaceintoSpaceAmericanmillionaireDennisTitowillalwaysbefamous.Hewasthefirsttouristinspace."Ispentsixt
TheRaceintoSpaceAmericanmillionaireDennisTitowillalwaysbefamous.Hewasthefirsttouristinspace."Ispentsixt
TheRaceintoSpaceAmericanmillionaireDennisTitowillalwaysbefamous.Hewasthefirsttouristinspace."Ispentsixt
TheRaceintoSpaceAmericanmillionaireDennisTitowillalwaysbefamous.Hewasthefirsttouristinspace."Ispentsixt
LearnaboutNobleGases(惰性气体)1Haveyoueverriddenonaballoon?Manytouristspotsofferballoonridesinorderforpeopl
随机试题
请简述局麻药的主要不良反应及注意事项。
以下属于细嫩烘青的有()。
男性,75岁。因腹股沟斜疝嵌顿2天急诊手术。术中见疝囊内有大团小肠,仍有活力,并有少量淡黄色渗出液,松解疝环,将小肠还纳腹腔并作疝修补术。术后第2天,病人觉腹痛较前加重,T38.8℃,腹部压痛、反跳痛、肌紧张,WBC18×109/L。最可能的原因是
A.生物毒类中毒B.乙二醇中毒C.氯酸盐中毒D.导眠能中毒E.短效巴比妥类中毒(2005年第121题)血液透析治疗急性中毒的首选指征是
下列哪项属于生物转化中两相反应的是
慢性边缘性骨髓炎如已明确骨质破坏的部位和范围,一般在病程多长时间可施行病灶清除术
关于血浆代用液叙述错误的是()。
提出“白板说”的哲学家是()。
A、2xe-xB、(一x2+2x)e-xC、e-xD、(2x一1)e-xC一方面,另一方面,比较两个计算结果可知应选C.
Nigeria’selectionwas______accordingtomostforeignobservers.
最新回复
(
0
)