首页
财务会计
医药卫生
金融经济
考公考编
外语考试
学历提升
职称考试
建筑工程
IT考试
其他
登录
职称考试
Learn about Noble Gases (惰性气体) 1 Have you ever ridden on a balloon? Many tou...
Learn about Noble Gases (惰性气体) 1 Have you ever ridden on a balloon? Many tou...
admin
2020-12-24
13
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 (氦). 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 (惰性气体).They were also listed under Group 0 in the old periodic table because scientists believed that the gases have zero valence (价)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 low chemical reactivity of these said gases.
5 Because of their properties, noble gases have many important applications. They are widely used in 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.
Noble gases are not very chemically .
选项
A lightest
B reactive
C important
D complete
E flammable
F unnecessary
答案
B
解析
第二段第一句中的react可以用be reactive替换。
转载请注明原文地址:https://ti.zuoweng.com/ti/1F9QKKKQ
相关试题推荐
LearnaboutNobleGases(惰性气体) 1Haveyoueverriddenonaballoon?Manytou...
LearnaboutNobleGases(惰性气体) 1Haveyoueverriddenonaballoon?Manytou...
LearnaboutNobleGases(惰性气体) 1Haveyoueverriddenonaballoon?Manytou...
LearnaboutNobleGases(惰性气体) 1Haveyoueverriddenonaballoon?Manyto...
LearnaboutNobleGases(惰性气体) 1Haveyoueverriddenonaballoon?Manyto...
LearnaboutNobleGases(惰性气体) 1Haveyoueverriddenonaballoon?spotso行...
LearnaboutNobleGases(惰性气体) 1Haveyoueverriddenonaballoon?spotso行...
LearnaboutNobleGases(惰性气体) 1Haveyoueverriddenonaballoon?spotso行...
LearnaboutNobleGases(惰性气体) 1Haveyoueverriddenonaballoon?Manytou...
LearnaboutNobleGases(惰性气体) 1Haveyoueverriddenonaballoon?Manytou...
随机试题
附设在汽车库、修车库内的消防控制室、自动灭火系统的设备室、消防水泵房等,应采用防
关于超货币供给理论,以下说法不正确的是()。 A.认为只有银行能够利用信贷方
最适于作疏水性药物润湿剂的HLB值是 A、HLB值为15~18 B、HLB
工程开工前,项目部应根据()对检测设备的精度要求和生产需要编制“计量检测设备配备
中央银行参与金融市场的主要目的不包括( )。
中国居民“平衡膳食宝塔”的最底层即居民膳食中最基本的组成部分是()
集合资产管理计划推广期间,应当由()负责托管与集合资产管理计划推广有关的全部
下列哪些不是创伤的临床指征()A.牙龈出现缘突B.牙槽骨的垂直吸收C.牙龈出血D.个别牙的倾斜E.牙周膜间隙增宽
16.国家对危险化学品生产、储存实行()制度。A.审查B.审批C.登记D.备案
可用作中毒后物理性拮抗剂的有A:绿豆汤B:蛋白C:药用炭D:血液透析E:牛乳