Textbook Question
A selenium-75 source is producing 300 rem at a distance of 2.0 m?b. What is its intensity at 25 m?
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17. Radioactivity and Nuclear Chemistry
Measuring Radioactivity
Multiple Choice
Which radioactive isotope is most commonly used to date ancient rocks in geological (radiometric) dating?
A
(phosphorus-32)
B
(carbon-14)
C
(iodine-131)
D
(uranium-238)
Verified step by step guidance1
Understand that radiometric dating relies on the decay of radioactive isotopes to estimate the age of rocks and fossils.
Recognize that different isotopes are used for dating materials of different ages and types due to their half-lives.
Note that carbon-14 is commonly used for dating once-living things up to about 50,000 years old, but it is not suitable for dating ancient rocks because its half-life is too short.
Identify that uranium-238 has a very long half-life (about 4.5 billion years), making it ideal for dating ancient geological materials such as rocks.
Conclude that uranium-238 is the most commonly used radioactive isotope for dating ancient rocks in geological radiometric dating.
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