Answer: "hazardous substance" .
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Answer:
Explanation:
Helium is the second most abundant element in the universe, but here on earth, it's rather rare. Most people guess that we extract helium from the air, but actually we dig it out of the ground. Helium can be found in certain parts of the world, notably in Texas, as a minor component in some sources of natural gas.
Helium is generated underground by the radioactive decay of heavy elements such as uranium and thorium. Part of the radiation from these elements consists of alpha particles, which form the nuclei of helium atoms. ... Helium can also be produced by liquefying air and separating the component gases
When the gas contains more than about 0.4% helium by volume, a cryogenic distillation method is often used in order to recover the helium content. Once the helium has been separated from the natural gas, it undergoes further refining to bring it to 99.99+% purity for commercial use.
Scientists<span> are working on ways to </span>make embryonic<span> stem </span>cells<span> without destroying </span>embryos<span> and to </span>make cells<span> that </span>behave like embryonic<span> stem </span><span>cells
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These pairs are found in double strand of DNA and RNA where the bonds between them connect the two strands making the double stranded structures possible.
