So that no one gets hurt, and the experiment isn't rendered void.
If you have a second fixture around, you can use the same test of putting a tube in a working socket and see if it lights. It is not uncommon in fluorescent fixtures to have the ballast burn out. You may detect a burnt smell or see the bulbs flickering.
Tsunami, I think, maybe a flood
Oxygen-16 and Carbon-12 are stableisotopes of elements O and C respectively. Hence, they do not have half-lives. But Carbon-14 andUranium-238 are radioactive isotopes. Among them Carbon-14 has relatively short half-life as about 5730 years while Uranium-238 has a long half-life as about 4.5 billion years.
Answer is. uranium-238
