Problem 12
Technetium-99 is used in medicine as a source of radiation. A typical dose is \(25 \mathrm{mCi}\). How long does it take for the activity to reduce to \(0.100 \mathrm{mCi}\) ? The half-life of \({ }^{99}\) Tc is 210,000 y.
Problem 12
The cyclopentadienyl anion \(\left(\mathrm{C}_{5} \mathrm{H}_{5}^{-}\right)\) is an organic ion that can make ionic compounds with positive ions of radioactive elements, such as \(\mathrm{Np}^{3+}\). Balance the following reaction: \(\mathrm{NpCl}_{3}+\mathrm{Be}\left(\mathrm{C}_{5} \mathrm{H}_{5}\right)_{2} \rightarrow \mathrm{Np}\left(\mathrm{C}_{5} \mathrm{H}_{5}\right)_{3}+\mathrm{BeCl}_{2}\)
Problem 12
Carbon-11 is a radioactive isotope used in positron emission tomography (PET) scans for medical diagnosis. Positron emission is another, though rare, type of radioactivity. The half-life of carbon-11 is 20.3 min. If \(4.23 \times 10^{-6} \mathrm{~g}\) of carbon- 11 is left in the body after \(4.00 \mathrm{~h}\), what mass of carbon-11 was present initially?
Problem 12
Technetium has an atomic number of \(43 .\) Write the nuclear equation for the beta particle emission of technetium-99. What is the daughter isotope?
Problem 13
If the half-life of hydrogen-3 is \(12.3 \mathrm{y}\), how much time does it take for \(99.0 \%\) of a sample of hydrogen-3 to decay?
Problem 13
What is a chain reaction?
Problem 14
The gamma ray emitted when oxygen-19 gives off a beta particle is \(0.197 \mathrm{MeV}\). What is its energy in joules?
Problem 14
If the half-life of carbon-14 is \(5,730 \mathrm{y}\), how long does it take for \(10.0 \%\) of a sample of carbon-14 to decay?
Problem 14
Why must uranium be enriched to supply nuclear energy?
Problem 15
Which penetrates matter more deeply- alpha particles or beta particles? Suggest ways to protect yourself against both particles.
