Question

Which is more radioactive U 235 or U 238?

Answer 1

1. Radioactive elements are those elements whose nuclei are unstable in nature and therefore they emit the radiations to become stable.
2. Uranium is a radioactive element and $\mathrm{U}-235\mathrm{and}\mathrm{U}-238$ are isotope of Uranium.
3. There are generally three types of decay that occur such as alpha, beta, and gamma.
4. The decay depends upon the number of emitting particles.
5. In $\mathrm{U}-235$ there are $92\mathrm{protons}\mathrm{and}143\mathrm{neutrons}$ , and in $\mathrm{U}-238$ there are$92\mathrm{protons}\mathrm{and}146\mathrm{neutrons}$.
6. This implies that $\mathrm{U}-238$ has three more neutrons compared with$\mathrm{U}-235$.
7. Therefore, an unstable nucleus continuously decays to achieve stability and so a lesser number of neutrons are stable and more radioactive in nature.
8. In general, uranium-235 and uranium-234 pose a greater radiological health risk than uranium-238 because they have much shorter half-lives, decay more quickly, and are thus "more radioactive." Because all uranium isotopes are primarily alpha emitters, they are only hazardous if ingested or inhaled.
9. Hence we concluded that $\mathrm{U}-235$ is more radioactive.