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The count rate of a radioactive material is 800 count/min. If the half-life of th...


Question

The count rate of a radioactive material is 800 count/min. If the half-life of the material is 4 days, what would the count rate be in 16 days later

Options

A) 200 count / min

B) 100 count / min

C) 50 count / min

D) 25 count / min


The correct answer is C.

Explanation:

116 days = 4 half - lives
Thus, after 4 half lives the fraction left of any radioactive materials is given by (1/2)4 = 1/16
∴ Count rate / amount left = 1/16 x 800/1
= 50 count / min

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Dicussion (1)

  • 116 days = 4 half - lives
    Thus, after 4 half lives the fraction left of any radioactive materials is given by (1/2)4 = 1/16
    ∴ Count rate / amount left = 1/16 x 800/1
    = 50 count / min

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