题目内容
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A. fossilized shellfish.
B. An animal skull.
C. A dead tree.
D. A giant crystal.
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A. The average time it takes for half of a group to decay.
B. Half the time it takes for a group to decay.
C. Half an hour for an individual nucleus to decay.
D. Half of the carbon present in a living organism.
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A. Because it was an example in the textbook.
Because he is using popcorn in a laboratory demonstration.
C. Because popcorn is a good analogy for half-lives.
D. Because popcorn is a carbon-based life form.
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A. It is the only accurate isotope for radiometric dating.
B. It represents most of the carbon in living things.
C. It has a half-life of almost 50 billion years.
D. It is used to estimate the age of carbon-based life forms.
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