Half-life: Quiz questions
 
 

 

 

  1. A radioactive substance has a half-life of 30 minutes.
    What fraction of the atoms will not have decayed after 1 hour?

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  2. Another substance has a half-life of 3 hours.
    What fraction of the atoms will have decayed after 6 hours?
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  3. A researcher measures 200 counts per minute coming from a radioactive source at midday.
    At 3 o'clock, she finds that this has dropped to 25 counts per minute.
    What is the half-life of the radioactive source?
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