题目内容
约里奥·居里夫妇因发现人工放射性而获得了1935年的诺贝尔化学奖,他们发现的放射性元索
衰变成
的同时放出另一种粒子,这种粒子是 。
是
的同位素,被广泛应用于生物示踪技术。1mg
随时间衰变的关系如图所示,请估算4mg的
经多 天的衰变后还剩0.25 mg。![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241354097345780.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824135408549442.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824135408939473.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824135408985430.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824135408549442.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824135408985430.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824135408985430.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241354097345780.png)
正电子,56天
根据方程式两端质量数,质子数守恒,可得,放出的这种电子为正电子,从图中可知1mg的
衰变成0.5mg需要14天可知4mg的
经56天的衰变后还剩0.25 mg
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824135408985430.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824135408985430.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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