<span>The correct answer is b. Radon. Oxygen, Hyrdrogen, and Boron, are not radioactivel ike Radon and it regenerates quickly meaning that even though it has a short half-life period, it stays for a long time once released. It also has no taste so it's difficult to notice without proper gear because you can't feel it.</span>
Answer:
Explanation: In the previous section we listed four characteristics of radioactivity and nuclear decay that form the basis for the use of radioisotopes in the health and biological sciences. A fifth characteristic of nuclear reactions is that they release enormous amounts of energy. The first nuclear reactor to achieve controlled nuclear disintegration was built in the early 1940s by Enrico Fermi and his colleagues at the University of Chicago. Since that time, a great deal of effort and expense has gone into developing nuclear reactors as a source of energy. The nuclear reactions presently used or studied by the nuclear power industry fall into two categories: fission reactions and fusion reactions
Steel is an alloy and consists of more than one element (mainly iron and carbon), therefore steel is a mixture.
