Question

Radioactive Half-life

Years |
Element A Remaining Radioactive Atoms |
Element B Remaining Radioactive Atoms |
Element C Remaining Radioactive Atoms |
Element D remaining Radioactive Atoms |

0 |
100 |
100 |
100 |
100 |

1000 |
50 |
85 |
90 |
95 |

2000 |
25 |
72 |
81 |
90 |

3000 |
13 |
61 |
73 |
86 |

4000 |
6 |
52 |
66 |
81 |

5000 |
3 |
44 |
59 |
77 |

6000 |
2 |
38 |
53 |
74 |

7000 |
1 |
32 |
48 |
70 |

8000 |
0 |
27 |
43 |
66 |

9000 |
0 |
23 |
39 |
63 |

10000 |
0 |
20 |
35 |
60 |

11000 |
0 |
17 |
31 |
57 |

12000 |
0 |
14 |
28 |
54 |

13000 |
0 |
12 |
25 |
51 |

14000 |
0 |
10 |
23 |
49 |

15000 |
0 |
9 |
21 |
46 |

16000 |
0 |
7 |
19 |
44 |

17000 |
0 |
6 |
17 |
42 |

18000 |
0 |
5 |
15 |
40 |

19000 |
0 |
5 |
14 |
38 |

20000 |
0 |
4 |
12 |
36 |

According to your data, what are the approximate half-lives of the hypothetical elements A, B, C, and D?

Which of the four hypothetical substances you investigated would be most harmful to living organisms?

What part of an original isotope’s number of atoms remains after two half-lives?

After three half-lives of an isotope, 1 billion (one-eighth) of the original isotope’s atoms still remain in a certain amount of this element. How many atoms of the daughter product would you expect to be present?

By measuring the amounts of parent isotope and daughter product in the minerals contained in a rock, and by knowing the half-life of the parent isotope, a geologist can calculate the absolute age of the rock. A rock contains 125 g of a radioisotope with a half-life of 150,000 years and 875 g of its daughter product. How old I the rock according to the radiometric dating method?

Answer #1

What is half-life of a radioactive element?
The time taken for the parent element to disappear.
The time taken for half of the original number of nuclei to
decay
The time taken for the volume of a sample to reduce to half its
original value
The time taken for the mass of a sample to reduce to half its
original value.
The number of electrons in a normal atom is the same as:
(i) the number of protons in its...

1. Given that a freshly prepared radioactive isotope has a
half-life of 10 days, the percentage of it remaining after 30 days
is
A
30.0 %.
B
10.0 %.
C
12.5 %.
D
72.5 %.
2. During a second half-life, the original
material has decayed
A
25%.
B
50%.
C
75%.
D
100%.

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