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WorksheetsHalf-Life Calculations
Total questions: 21
Worksheet time: 1hrs 3mins
After 22,800 years, approximately what percentage of the original carbon-14 remains?
15%
12.5%
6.25%
3.125%
The % of the parent isotope remaining after 1 Half Life.
50%
25%
12.5%
6.25%
The % of the parent isotope remaining after 2 Half Lives.
50%
25%
12.5%
6.25%
The mass of a radioisotope falls from 1.6g to 0.1g in 2 hours. What is the half-life of this radioisotope (in minutes)?
(a)
If a 1g sample of a radioisotope with a half-life of 3 days has an activity of 32 counts sec-1, how long would it take for the activity of a 2g sample to fall to 8 counts sec-1?
Give your answer in days
(a)
A medical radioisotope has a half-life of 1.5 hours. Its radioactivity was recorded as 10,000 counts min-1 at 9am. What will the count rate be by 3pm?
(a)
Phosphorus-32 is a radioisotope with a half-life of 14.3 days. If you start with 4g of phosphorus-32, how many half-lives will have passed after 57.2 days?
(a)
Sodium-24 has a half-life of 15 hours. How much sodium-24 will remain in an 18g sample after 60 hours?
Do not round your answer.
(a)
After 42 days, a 2.0g sample of phosphorus-32 contains only 0.25g of the isotope. What is the half-life of phosphorus-32?
(a)
Iodine-131 has a half-life of 8 days. What percentage of the sample would remain at the end of 32 days?
(a)
The half-life of chromium-51 is 28 days. If the sample contained 510 grams, how much Cr-51 would remain after 56 days?
(a)
If 20.0g of a radioisotope are present at 1pm and 5.0g remain at 2pm, what is the half-life of this isotope?
Give your answer in minutes.
(a)
The half-life of iodine-125 is 60 days. What percentage of iodine-125 would be left after 360 days?
Do not round your answer
(a)
The half-life of thorium-227 is 18.72 days. How many days are required for 4.68g to remain if you start with 74.88 grams?
Do not round your answer
(a)
If a source had an activity of 12 kBq and a half-life of 6 hours, what would the activity be after one day? Give your answer in Bq
(a)
A radioactive source had an activity of 1 MBq. After 30 days it had fallen to 62.5 kBq. Calculate the half-life of this sample.
(a)
A source with an activity of 300 Bq had a half-life of 14 days. The source was measured some time later and the activity was recorded as 9.375 Bq. How much time had passed?
(a)
A source has a half-life of 6 days. After 36 days the activity of the source had fallen to 7 Bq. What was the intial activity of the source?
(a)
