A scientist observes that the particles emitted by a radioactive substance cannot be detected when the substance is enclosed in a thin sheet of paper. He thinks that the sample is polonium (Po, atomic number 84) and that it is decaying to astatine (At, atomic number 85) by beta decay. Which statement correctly assesses his conclusion?

a) It could be this reaction, because nuclear fission does not release particles.

b) It could be this reaction, because alpha particles are blocked by the paper.

c) It cannot be this reaction, because beta particles would penetrate the paper.

d) It cannot be this reaction, because gamma rays are blocked by paper.

Question

Reed Thomas

Chemistry

13 July, 01:12

A scientist observes that the particles emitted by a radioactive substance cannot be detected when the substance is enclosed in a thin sheet of paper. He thinks that the sample is polonium (Po, atomic number 84) and that it is decaying to astatine (At, atomic number 85) by beta decay. Which statement correctly assesses his conclusion?

a) It could be this reaction, because nuclear fission does not release particles.

b) It could be this reaction, because alpha particles are blocked by the paper.

c) It cannot be this reaction, because beta particles would penetrate the paper.

d) It cannot be this reaction, because gamma rays are blocked by paper.

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Answers (1)

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Alena Cohen · Answer 1

C) It cannot be this reaction, because the beta particles would penetrate the paper

In terms of penetration power, alpha particles have the lowest. A sheet of paper would be sufficient in stopping only alpha particles. Beta particles would require a slightly thick aluminium sheet to be blocked, while gamma rays require thick slabs of concrete for them to be stopped.