Name ____________________________________

 

Radioisotope Dating Quiz (Answer Key)

 

1. A scientist has discovered a new radioisotope. She wants to use the isotope to date dinosaur bones in her lab. The dinosaur bones are 100 million years old. (13 pt)

Time Elapsed	Undecayed Isotope Remaining
0 years	100 grams
10,000 years	75 grams
15,000 years	50 grams
30,000 years	25 grams
37,000 years	17 grams
45,000 years	12.25 grams
49,000 years	10 grams

 

What is the half-life of the new radioisotope?

15,000 years

 

Will this radioisotope work to date the dinosaur bones? Why or why not?

No. The dinosaur bones are 100 million years old. After 100 million years, this there will be only very miniscule amounts of this isotope left. It will be very difficult to produce an accurate date. The scientist would need a radioisotope with a much greater half life to date the bones.

 

2. Given the information plotted below, which isotope has a greater half life? Which isotope would be used to date a relic that was thought to be 300,000-500,000 years old? (12pt)

Radioisotope #2: Wiinterium. Winterium will have passed through a few half-lives over 300,000-500,000 years, but should still be present and detectable. The Summerium would be almost entirely decayed away in that many years.

 

Challenge Question (4pt Extra Credit)

During World War II the United States dropped nuclear bombs on Japan. These bombs released many new radioisotopes into the environment. How might this affect radioisotope dating studies in Japan in the future?

Future tests scientists might try to run on relics from out current period would be very hard to interpret. The nuclear revolution, including nulcear reactors and nuclear weapons have changed the radioisotope content of the earth's surface from the constant values normally assumed in radioisotopic dating.

 

 

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