Problems About Radioactivity and Nuclear Chemistry
1. At 8:00 a.m., a patient receives a 58-mg dose of I -131 to obtain an image of her thyroid. If the nuclide has a half-life of 8 days, what mass of the nuclide remains in the patient at 5:00 p.m. the next day? (Assume no excretion of the nuclide from the body).
Express your answer using two significant figures.
2. A radioactive sample contains 1.55g of an isotope with a half-life of 3.8 days. What mass of the isotope will remain after 5.5 days? (Assume no excretion of the nuclide from the body.) Express your answer using two significant figures.
3. A particular smoke detector contains 1.45μCi of 241 Am, with a half-life of 458 years. The isotope is encased in a thin aluminum container. Calculate the mass of 241 Am in grams in the detector. Express your answer numerically in grams.
4. The following conversion factors may help you when working this problem:
Activity in becquerels (Bq ) = activity in disintegrations per second (dps).
1.00 mCi=3.70×10 7 Bq. Neutron activation analysis for a sample of a rock revealed the presence of 59 26 Fe, which has a half-life of 46.3days. Assuming the isotope was freshly separated from its decay products, what is the mass of 59 26 Fe in a sample emitting 1.00 mCi of radiation? Express your answer in grams to three significant figures.
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Solution Preview
1. A = Ao x e^-(0.693t/t1/2) = 58 x e^-(0.693 x 33/(8 x 24)) = 51 mg
2. A = Ao x e^-(0.693t/t1/2) = ...
Solution Summary
The solution discusses the problems about radioactivity and nuclear chemistry.
Nuclear Chemistry
The reaction represented by the description "An atom of lead-210 decays by emission of an alpha particle" is:
Question 3
The reaction represented by the description "An atom of copper-66 decays by beta emission" is
Question 4
The reaction represented by the description "An atom of titanium-45 decays by positron emission" is
Question 5
The reaction represented by the description "An atom of metastable strontium-87 undergoes gamma decay" is
Question 6 T
The reaction represented by the description "An atom of selenium-75 undergoes electron capture" is
Question 7
Beta emission can best be described as
a. emission of two protons and two neutrons from an unstable nucleus.
b. transformation of a neutron into a protron and an electron that is ejected from the nucleus.
c. transformation of a proton into a neutron by combination with an electron.
d. annihilation of a beta particle by a positron.
e. annihilation of a neutrino by an anti-neutrino.
Question 8
Alpha emission can best be described as
a. emission of two protons and two neutrons from an unstable nucleus.
b. transformation of a proton into a neutron and an electron that is ejected from the nucleus.
c. transformation of a proton into a neutron by combination with an electron.
d. annihilation of a beta particle by a positron.
e. annihilation of a neutrino by an anti-neutrino.
Question 9
All of these are common modes of radioactive decay except __________.
a. alpha emission
b. beta emission
c. electron capture
d. positron emission
e. phosphorescence
Question 10
The rule that the mass number of stable isotopes is always at least twice the atomic number is true for all nuclides except
a. helium-3
b. beryllium-10
c. strontium-90
d. magnesium-28
e. vanadium-52