chemistry

A 1.00-g sample of carbon from a modern
source gave 15.3 disintegrations per minute. A sample of carbon from an “old” source gave 920 disintegrations per hour. What is the age of the “old” sample of carbon? The half-life of carbon-14 is 5.73×103 year.
a. about 34,400 years
b. about 345,000 years
c. about 20 million years
d. less than a few years

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  1. Typo: The half-life is 5.7x10^3

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  2. Without even doing the math it the change in disintegrations is merely .03333, the sample must have decayed for

    d. less than a few years

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  3. whoops, i did the math and it came out to about 34,400 years. Sorry for my earlier answer

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  4. k = 0.693/t1/2
    k = 0.693/5.7E3 = 1.22E-4

    ln(15.3333/15.3) = 1.22E-4(t)
    t = about 18 year.

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  5. vanden bout

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  6. actually drake was right on his first answer i had this question on my homework and it is d. less than a few years :)

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