WorksheetsRadioactive Decay Earth Science
Total questions: 10
Worksheet time: 36mins
What percentage of radioactive atoms will be left after four half lives?
25.0%
12.5%
6.25%
3.125%
If the half-life of carbon is 5,700 years, how old is a bone that has 12.5% of the original amount of radioactive carbon-14 remaining?
5,700 years
11,400 years
17,100 years
22,800 years
Which radioactive isotope is most often used when determining the age of fossil bones found in sediments deposited 40,000 years ago?
carbon-14
potassium-40
uranium-238
rubidium-87
A fossil formed 11,400 years ago. Which percentage of the original amount of carbon-14 remains in the fossil? Remember, the half-life of carbon-14 is 5,700 years.
100%
50%
25%
12.5%
Radioactive dating of fossils and rocks is possible because radioactive isotopes
are found in all fossils and rocks
are easily collected and measured
decay into organic substances
decay at a predictable rate
How much of an 800-gram sample of potassium-40 will remain after 3 half-lives has passed?
50 grams
100 grams
200 grams
400 grams
How old is a fossil that has radioactively decayed through 4 half-lives of carbon-14?
5,700 years
17,100 years
22,800 years
28,500 years
A whalebone that originally contained 200 grams of radioactive carbon-14 now contains 25 grams of carbon-14. How many carbon-14 half-lives have passed since this whale was alive?
1
2
3
4
If a sample of a radioactive substance is crushed the half-life of the substance will
decrease
increase
remain the same
An archeologist found an ancient skeleton estimated to be 10,000 to 25,000 years old. Which radioactive isotope would be most useful for finding the age of the skeleton?
carbon-14
potassium-40
uranium-238
rubidium-87
