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Thorium-234 has a half life of 24days. If 72 days passed before a corspe was found, what fraction of Thorium-234 would you expect to still be radioactive in the vitcims body?

2007-03-17 05:47:11 · 6 answers · asked by vballchik104 1 in Science & Mathematics Biology

6 answers

After 24 days, half the thorium will be gone (left with 50%). After another 24 days, another half again will be gone, so we're now down to 25% of the original content. After another 24 days ( or 72 days), another half is lost meaning we're down to 12.5% (or 1/8th) of the original amount.

2007-03-17 05:52:05 · answer #1 · answered by dudara 4 · 0 0

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The half life equation is

y = 1 / 2^ t

72 = days passed
24 = half life
Y = fraction of original material remaining
t = number of half lives =72 / 24 = 3

y = 1 / 2 ^3

y = 1/8
answer:
1/8 of the original Thorium -234 still remains
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To calculate the age (T) of a sample use

T = (half Life) x log2 (1/y)

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2007-03-17 13:05:02 · answer #2 · answered by Anonymous · 0 0

easy 72 days correspond to 72/24 =3 half life

in three half lives the fraction of Th234 is (1/2)^3 = 1/8

2007-03-17 12:51:29 · answer #3 · answered by maussy 7 · 0 0

depends on how much you started with...1/3 of the starting amount or 1/2^#half lifes

2007-03-17 13:24:43 · answer #4 · answered by lalalalalalala 1 · 0 0

If you had 100% on day one, on day 24 you would have 50%; on day 48 you would have 50% of what you had on day 24; on day 72 you would have 50% of what you had on day 48; and so on.

SCIENCE TEACHER

2007-03-17 12:53:01 · answer #5 · answered by CAROL P 4 · 1 0

1/8
for every half life multiply times 1/2

2007-03-17 13:56:53 · answer #6 · answered by wesnaw1 5 · 0 0

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