If You Begin with a Sample of 2

question 21

Multiple Choice

If you begin with a sample of 2.50 moles of a radioactive isotope and there are 2.05 * 10²¹ atoms left after one hour,what is the mean lifetime of this isotope?

• A)8.4 minutes
• B)7.5 minutes
• C)6.3 minutes
• D)9.1 minutes

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