The most significant source of natural radiation is radon-222. \(^{222}
\mathrm{Rn},\) a decay product of \(^{238} \mathrm{U},\) is continuously
generated in the earth's crust, allowing gaseous Rn to seep into the basements
of buildings. Because \(^{222} \mathrm{Rn}\) is an \(\alpha\) -particle producer
with a relatively short half-life of 3.82 days, it can cause biological damage
when inhaled.
a. How many \(\alpha\) particles and \(\beta\) particles are produced when \(^{238}
\mathrm{U}\) decays to \(^{222} \mathrm{Rn}\) ? What nuclei are produced when
\(^{222} \mathrm{Rn}\) decays?
b. Radon is a noble gas so one would expect it to pass through the body
quickly. Why is there a concern over inhaling \(^{222} \mathrm{Rn}\) ?
c. Another problem associated with \(^{222} \mathrm{Rn}\) is that the decay of
\(^{222} \mathrm{Rn}\) produces a more potent \(\alpha\) -particle producer
\(\left(t_{1 / 2}=3.11 \mathrm{min} \text { ) that is a solid. What is the
identity of the }\right.\) solid? Give the balanced equation of this species
decaying by \(\alpha\) -particle production. Why is the solid a more potent
\(\alpha\) -particle producer?
d. The U.S. Environmental Protection Agency (EPA) recommends that 222 Rn
levels not exceed 4 \(\mathrm{pCi}\) per liter of air \(\left(1 \mathrm{Ci}=1
\text { curie }=3.7 \times 10^{10} \text { decay events per second; }\right.\)
\(1 \mathrm{pCi}=1 \times 10^{-12} \mathrm{Ci}\) . Convert 4.0 \(\mathrm{pCi}\)
per liter of air into concentrations units of \(^{222} \mathrm{Rn}\) atoms per
liter of air and moles of \(^{2222} \mathrm{Rn}\) per liter of air.