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