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
下面的短文后列出了 7 个句子,请根据短文的内容对每个句子做出判断:如果该句提供的是正确信息,请选择A ; 如果该句提供的是错误信息,请选择B ; 如果该...
下面的短文后列出了 7 个句子,请根据短文的内容对每个句子做出判断:如果该句提供的是正确信息,请选择A ; 如果该句提供的是错误信息,请选择B ; 如果该...
admin
2020-12-24
71
问题
下面的短文后列出了 7 个句子,请根据短文的内容对每个句子做出判断:如果该句提供的是正确信息,请选择A ; 如果该句提供的是错误信息,请选择B ; 如果该句的信息文中没有提及,请选择C。
Radiocarbon Dating
Nowadays scientists can answer many questions about the past through a technique called radiocarbon (放射性碳), or carbon-14, dating. One key to understanding how and why something happened is to discover when it happened.
Radiocarbon dating was developed in the late 1940s by physicist Willard F. Libby at the University of Chicago. An atom of ordinary carbon, called carbon-12, has six protons(质子)and six neutrons(中子)in its mKJteus(原子核).Carbon-14, or C-14, is a radioactive.
unstable form of carbon that has two extra neutrons. It returns to a more stable form of carbon through a process called decay ( 衰减). This process involves the loss of the extra neutrons and energy from the nucleus.
In Libby’s radiocarbon dating technique, the weak radioactive emissions (放射) from this decay process are counted by instruments such as a radiation detects and counter. The decay rate is used to determine the proportion of C-14 atoms in the sample being dated.
Carbon-14 is produced in the Earth’s atmosphere when nitrogen (氮)-14,or N-14, interacts with cosmic rays (宇宙射线). Scientists believe since the Earth was formed,the amount of nitrogen in the atmosphere has remained constant. Consequently, C-14 formation is thought to occur at a constant rate. Now ratio of C-14 to other carbon atoms in the atmosphere is known. Most scientists agree that this ratio is useful for dating items back to at least 50, 000 years.
All life on Earth is made of organic molecules (分子) that contain carbon atoms coming from the atmosphem. So all living things have about the same ratio of C-14 atoms to other carbon atoms in their tissues (组织). Once an organism (有机体) dies it stops taking in carbon in any form, and the C-14 already present begins to decay. Over time the amount of C-14 in the material decreases, and the ratio of C-14 to other carbon atoms goes down. In terms of radiocarbon dating, the fewer C-14 atoms in a sample, the older that sample is.
An atom of ordinary carbon has six protons and eight neutrons.
选项
A Right
B Wrong
C Not mentioned
答案
B
解析
转载请注明原文地址:https://ti.zuoweng.com/ti/tElQKKKQ
相关试题推荐
下面的短文有15处空白,请根据短文内容为每处空白确定1个最佳选项。 YoungAdultsWhoExerciseGetHigher...
下面的短文有15处空白,请根据短文内容为每处空白确定1个最佳选项。 YoungAdultsWhoExerciseGetHigher...
下面的短文有15处空白,请根据短文内容为每处空白确定1个最佳选项。 YoungAdultsWhoExerciseGetHigher...
下面的短文有15处空白,请根据短文内容为每处空白确定1个最佳选项。 YoungAdultsWhoExerciseGetHigher...
下面的短文有15处空白,请根据短文内容为每处空白确定1个最佳选项。 YoungAdultsWhoExerciseGetHigher...
下面的短文有15处空白,请根据短文内容为每处空白确定1个最佳选项。 YoungAdultsWhoExerciseGetHigher...
下面的短文有15处空白,请根据短文内容为每处空白确定1个最佳选项。 YoungAdultsWhoExerciseGetHigher...
下面的短文有5处空白,短文后有6个句子,其中5个取自短文,请根据短文内容将其分别放回原有位置,以恢复文章原貌。 Mt.DesertIs...
下面的短文有5处空白,短文后有6个句子,其中5个取自短文,请根据短文内容将其分别放回原有位置,以恢复文章原貌。 Mt.DesertIs...
下面的短文有5处空白,短文后有6个句子,其中5个取自短文,请根据短文内容将其分别放回原有位置,以恢复文章原貌。 Mt.DesertIs...
随机试题
目前,国际海空联运的主要线路有远东--欧洲、远东--中南美和() 三条。
每提起屈原的《涉江》,人们总喜欢把它与《离骚》作比较,有人说它是“一部小型的《离
利用横道图表示工程进度计划的缺点有()
下颌第一乳磨牙牙冠解剖形态中哪一点是错误的 A颊面好似一个以近中缘为底的三角形
信用卡个人贷款业务与一般贷款业务的相同点包括()。A.都是商业银行的重要业务B.有着相同的业务属性C.都是根据贷款申请人资信情况给予一定的授信额度D.都
随着网络直播的广泛应用,个别人为了牟取利益而利用网络直播传播“涉黄”信息.对此行为,下列说法正确的是()。A.这是个人行为,批评教育即可B.这是个人自由,不
男性,58岁,渐发性双上肢震颤、活动不利半年。既往体健,无慢性疾病史。头颅MRI无异常发现。体检:面部表情呆滞,四肢肌张力增高,齿轮样,双上肢向前平伸时可...
Anotablyshortman,heplaysbasketballwithhisstaffseveraltimesaweek....
海运提单是国际海洋运输中最重要的单据。下列选项中,不属于其性质和作用的一项是()。A:货物收据B:物权凭证C:运输保险的证明D:运输契约的证明
下列各项中,属于会计对象的有______。A.资金运动B.价值运动C.社会生产过程中的所有经济活动D.社会再生产过程中能以货币表现的经济活动