A radioactive isotope has a half-life of 74.0 min . A sample is prepared that ha
ID: 1450306 • Letter: A
Question
A radioactive isotope has a half-life of 74.0 min . A sample is prepared that has an initial activity of 1.30×1011 Bq .
Part A
How many radioactive nuclei are initially present in the sample?
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Part B
How many are present after 74.0 min ?
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Part C
What is the activity after 74.0 min ?
A radioactive isotope has a half-life of 74.0 min . A sample is prepared that has an initial activity of 1.30×1011 Bq .
Part A
How many radioactive nuclei are initially present in the sample?
N =SubmitMy AnswersGive Up
Part B
How many are present after 74.0 min ?
N =SubmitMy AnswersGive Up
Part C
What is the activity after 74.0 min ?
Explanation / Answer
Part A) Here, time constant tc = thalf/ln(2) = 74//ln(2) = 106.759 min
radioactive nuclei are initially present in the sample = 106.759 * 60 * 1.30×1011
= 8.327 * 1014
Part B) present after 74.0 min = 106.759 * 60 * 1.30×1011 /2
= 4.1635 * 1014
Part C) activity after 74.0 min = 1.30×1011/2
= 6.5 * 1010 Bq