Indoor air pollution. Uranium is naturally present in rock and soil. At one step
ID: 1415438 • Letter: I
Question
Indoor air pollution. Uranium is naturally present in rock and soil. At one step in its series of radioactive decays, 238U produces the chemically inert gas radon-222, with a half-life of 3.82 days. The radon seeps out of the ground to mix into the atmosphere, typically making open air radioactive with activity 0.3 pCi/L. In homes, 222Rn can be a serious pollutant, accumulating to reach much higher activities in enclosed spaces. If the radon activity exceeds 4 pCi/L, the Environmental Protection Agency suggests taking action to reduce it, such as by reducing infiltration of air from the ground. I HAVE A AND B, I JUST NEED C
(a) Suppose that the activity is actually 4.8 pCi/L. Convert this to units of becquerel per cubic meter.
Bq/m3
(b) How many 222Rn atoms are in one cubic meter of air displaying this activity?
(c) What fraction of the mass of the air does the radon constitute?
Explanation / Answer
c) Density of air = 1.19 Kg/m2
Fraction of mass of Rn = 0.222 x (8.4571 x 107)/(1.19 x 6.022 x1023)
= 2.6199 x 10-17