Use the Fact That the Quantity of a Radioactive Substance

question 82

Multiple Choice

Use the fact that the quantity of a radioactive substance after t years is given by where is the original amount of radioactive material and k is its half-life (the number of years it takes for half the radioactive substance to decay) . The half-life of strontium-90 is 25 years. Find the amount of strontium-90 remaining after 9 years if Round your answer to one decimal place.

• A) 13.6 kg
• B) 72.5 kg
• C) 7.5 kg
• D) 119.4 kg
• E) 0.2 kg

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