The Half-Life of a Radioactive Isotope Is 140 Days

question 62

Multiple Choice

The half-life of a radioactive isotope is 140 days.In how many days does the decay rate of a sample of this isotope decrease to one fourth its initial decay rate?

• A)35 days
• B)70 days
• C)105 days
• D)210 days
• E)280 days

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