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
43
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?
Paragraph 2______
选项
答案
E
解析
第2段主要讲述过去人们曾以为惰性气体是完全没有活性的。所以E选项How were noblegases understood in the past?“人们过去是如何理解惰性气体的”正确。
转载请注明原文地址:https://kaotiyun.com/show/BE8R777K
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.
Itishightimewe______someaction.
Peopleandanimalsaredifferent______theirreactionstodrugsandintheway______theirbodieswork.
TheRaceintoSpaceAmericanmillionaireDennisTitowillalwaysbefamous.Hewasthefirsttouristinspace."Ispentsixt
TheRaceintoSpaceAmericanmillionaireDennisTitowillalwaysbefamous.Hewasthefirsttouristinspace."Ispentsixt
TheRaceintoSpaceAmericanmillionaireDennisTitowillalwaysbefamous.Hewasthefirsttouristinspace."Ispentsixt
LearnaboutNobleGases(惰性气体)1Haveyoueverriddenonaballoon?Manytouristspotsofferballoonridesinorderforpeopl
LearnaboutNobleGases(惰性气体)1Haveyoueverriddenonaballoon?Manytouristspotsofferballoonridesinorderforpeopl
随机试题
C语言的保留字主要用于语句的构成,所有保留字均由______组成。
A.低渗性脱水B.等渗性脱水C.高渗性脱水D.低钠血症E.高钠血症大面积烧伤患者会出现
四环素可引起光敏感,服用这类药物期间,在阳光中暴露很短的时间就会造成严重的
正确确定垂直距离的目的,下列哪项是错误的
铁路建设单位对高速铁路和地质构造复杂的铁路建设工程实行工程地质勘察监理,或者在铁路线路及其邻近区域进行铁路建设工程施工不执行铁路营业线施工安全管理规定,影响铁路运营安全的,处理规定为()。
下列各项中,符合会计职业道德规范中“参与管理”基本要求的有()。
李某为某股份公司董事,2006年12月份取得工资5600元及董事费收入70000元。李某从董事费收入中拿出20000元通过红十字会向红十字事业捐赠。李某12月份应缴纳个人所得税( )元。
以下各项中,适用9%增值税税率的有()。
中国古诗词中关于美人的名篇很多,其中一阕是写于西汉时期的短歌,勾画出美丽无双的李夫人。下列哪句出于这首短歌?()
Accordingtocoveringscope,whichthreeclassescancomputernetworkbedivided?()
最新回复
(
0
)