i need help with these 3 questions please... A radioactive isotope of Bismuth un
ID: 1780715 • Letter: I
Question
i need help with these 3 questions please...
A radioactive isotope of Bismuth undergoes Beta Decay with a half-life of 6 days. How long (in days) will it take the Activity (A) of the sample to decrease to one-ninth of its original value? Assume that the original activity is Ao Submit Answer Tries 0/8 If the original activity of the Bismuth sample is 3.00x109 Bq, what will the activity (in Bq) be 8 days later? The Carbon-14 activity of an old sample of wood in an ancient statue is measured to be 0.9 as large as the activity of a recently cut piece of wood. How old (in years written as "yr") is the statue? In other words, how long ago was the old sample of wood cut? The half-life of Carbon-14 is 5760 years. Submit Answer Tries 0/8Explanation / Answer
1)Number of half lives = n
(1/2)^n = 1/9
9 = 2^n
n = log9/log2 = 3.17
Number of days = 6*3.17 = 19.02 days
2) Final activity = 3e9*(1/2)^(8/6) = 1.19*10^9 Bq
3) (1/2)^(T/5760) = 0.9
T/5760 log 0.5 = log 0.9
T = 5760*log 0.9 / log 0.5
= 875.5 years answer
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