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
Answer:
the central nervous system, cardiovascular, respiratory, and musculoskeletal systems
Explanation:
Ozone, which is also known as trioxygen, is a chemically bonded compound, and contains three oxygens.
A virus is not a bacteria, but it is caused by a bacteria. A virus causes the immune system to weaken.
Explanation:
<u>the Paleozoic Era </u>
The Precambrian era describes a period of time that pre-dates Cambrian. This time typically references the entire period of the history of earth before the formation of rocks containing identifiable fossils occurred. It covers the majority of Earth’s history and is divided into the Hadean, Archean and the Proterozoic era.
Just before the Cambrian eruption, in the Paleozoic Era the environment was oxygenated, culminating in an explosion of new life in the Proteozoic Eon (2500-541 million years ago) in the form of primitive blue-green algae named cyanobacteria and oxygen based species. Multicellular species followed later, along with structure at higher levels, and complex life. Oxygen levels grew gradually over this period of time, from low levels.
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