Problems of radioactive decay
1) The half ـlife of iodine131 ـis 8.1 days. How long will it take for three ـ
fourths of a sample of iodine 131 ـto decay?
2) Radon 222 ـis a radioactive gas with a half ـlife of 3.82 days. How long
would it take for fifteen ـsixteenths of a sample of radon 222 ـto decay?
3) Uranium 238 ـdecays slowly with a half ـlife of 4.47 billion years.
What percentage of a sample of uranium 238 ـwould remain after 13.4
billion years?
4) a sample of strontium90 ـis found to have decayed to one ـeighth of its
original amount After 87.3 years. What is the half ـlife of strontium90?ـ
5) a sample of francium212 ـwill decay to one ـsixteenth its original
amount after 80 minutes. What is the half ـlife of francium 212 ?ـ
6) The ratio of carbon 14 ـto carbon 12 ـis a prehistoric wooden artifact is
measured to be one ـeighth of the ratio measured in a fresh sample of
wood from the same region. The half ـlife of carbon 14 ـis 5.715 years .
Determine it age.
7) healh of officials are concerned about radon – 222 levels in the homes .
the half- life of radon – 222 is 3.82 days . if a sample of gas contain 4.38
microgramsof radon-222 , how much of remain in the sample after 15.2
days
