Which is/are false about T1/2 of radioisotopes
Iodine-131 (131I) is an important radioisotope of iodine discovered by Glenn Seaborg and John Livingood in 1938 at the University of California, Berkeley. It has a radioactive decay half-life of about eight days.
It is associated with nuclear energy, medical diagnostic and treatment procedures, and natural gas production.
It also plays a major role as a radioactive isotope present in nuclear fission products, and was a significant contributor to the health hazards from open-air atomic bomb testing in the 1950s, and from the Chernobyl disaster, as well as being a large fraction of the contamination hazard in the first weeks in the Fukushima nuclear crisis.
This is because I-131 is a major fission product of uranium and plutonium, comprising nearly 3% of the total products of fission (by weight).
See fission product yield for a comparison with other radioactive fission products. I-131 is also a major fission product of uranium-233, produced from thorium.
Ra-226: 1626 years
I-131: 60 years
Co-60: 5.26 years
Ir-192 : 74 years