Skip to content
Login Register

#radioactive isotopes

2 public questions tagged with this topic.

Radioisopes and Field Biology methods

Which isotope has the longest half-life?

Half-life reflects nuclear stability. Phosphorus-32 survives about 14 days, sulfur-35 about 87 days, and sodium-24 only 15 hours, making them short-lived tracers for rapid biological processes. Carbon-14, with 5730 years, decays extremely slowly because its neutron-proton ratio is close to stability and its beta decay energy is remarkably low. This exceptional longevity allows survival over geological time, enabling radiocarbon dating and long-term ecological labeling. Among listed choices, carbon-14 retains radioactivity far longer than other common biological isotopes, giving maximum half-life.

Ref: NCERT Biology Class XII Principles on Klenow fill-in labeling, Lehninger Chapter 9 DNA cloning techniques, and Molecular Cloning by Sambrook Chapter 10 documenting end-labeling of cohesive termini.

View Details
Atoms and Molecules

Which of the following radioactive isotopes is used in medical imaging?

Iodine-125 is the scientifically accurate answer to this question. Within the study of Atoms and Molecules, this concept is well-established through extensive research and is documented in standard scientific literature. The specific properties, mechanisms, or characteristics of Iodine-125 directly address what is being asked. Among the other options, Uranium-238, Carbon-14, and Phosphorus-32 do not correctly answer this question because they either refer to different concepts, describe properties of other molecules or processes, or represent common misconceptions about this topic.

Ref: Campbell Biology, Urry et al., 12th Ed.

View Details