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I have a question about a practice test!! Why is the correct answer B? I chose A. It doesn't make sense to me.

Radon is a radioactive gas that is invisible and odorless. It forms during the decay of uranium-238, and in decaying, itself produces solid heavy metal radioactive particles of polonium, lead, and bismuth. The parent element, uranium, is distributed in rocks and soils in many regions of the world, although usually in negligible amounts. However, concentrations of this element occur in certain rocks, and under certain conditions it is dissolved by underground water and carried over great distances before seeping into other rocks and soils.

Since radon is a gas, it can move from the ground into the air, where it is dispersed by the winds. If it infiltrates buildings, however, it can build up over time and lead to serious health problems. In fact, the radon itself is chemically inert and so does not enter into chemical reactions with other substances. It is readily dissolved in blood and circulates through the body until it is expelled, usually before it has had time to decay. The health problems associated with radon activity arise from the radioactive products of its disintegration, mentioned above.
Health problems associated with radon are caused by

A. radioactive uranium
B. certain heavy metals

C. decaying gases

D.  some chemical reactions

3 Answers by Expert Tutors

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Naina B. | Naina, a versatile tutorNaina, a versatile tutor
4.8 4.8 (155 lesson ratings) (155)
Hi Saori,
    Since I have worked with radioactive material and had to take a course about their safety, I know that  for sure radiactive particles as byproducts of any reaction and compound can cause health problems and therefore, correct answer is B as explained by Miguel. William has nicely explained you to rule out A, C and D, I am not repeating those again.
  Hope this is helpful as well.


Thank you, Naina!!
The health problems associated with radon activity (radiactive particles as by products of any reaction and compound).
Therefore, B is correct. 
Thanks alway!! 
William S. | Experienced scientist, mathematician and instructor - WilliamExperienced scientist, mathematician and...
4.4 4.4 (10 lesson ratings) (10)
Dear Saori,
It is not the radon itself that produces the problems (after all, it is an inert gas) but rather those other elements polonium, lead, and bismuth mentioned in the article.  All by themselves these are toxic metals whether they happen to be radioactive or not.
We can rule out A since you are not breathing in particles of uranium, rather the argon produced by uranium's decay.  Similarly, since radon is inert, it does not like to participate in chemical reactions, so we can rule out D.  I suppose we could make a case for answer C since the radon itself decays into those heavy metals we've already talked about.  Though I don't particularly like the way the question is worded, I guess I would have to go with answer B, since it is those heavy metals that cause all of the physical problems.


Thank you, William!!
The radon itself is not harmful but heavy metals are harmful for us, right?
Also, the argon produced by uranium's DECAY.
That's why A is not correct.
Thank you for your help!!
Miguel M. | Math and Science Tutor with 30+ Years Teaching ExperienceMath and Science Tutor with 30+ Years Te...
4.9 4.9 (93 lesson ratings) (93)
The reason that the answer is B is that radon breaks down into radioactive forms of three heavy metals, polonium, lead, and bismuth, and the last sentence states:"The health problems associated with radon arise from the radioactive products of its disintegration, mentioned above." Those "mentioned above" are the heavy metals.
It isn't answer A because uranium is not what is causing health problems associated with radon. Uranium is not making radon fall apart into these dangerous heavy metals.


Thank you, Miguel!!
The problem is that the radioactive products (polonium, lead and bismuth )  disintegrate. In the end, this is harmful for us. 
It also makes sense that  "mentioned above" are the heavy metals.
Thank you!!