Answer: b
Astatine is a chemical element with the symbol At and atomic number 85. It is the rarest naturally occurring element in the Earth’s crust occurring only as the decay product of various heavier elements . All of astatine’s isotopes are short-lived; the most stable is astatine-210 with a half-life of 8.1 hours. A sample of the pure element has never been assembled because any macroscopic …
Stellar nucleosynthesis is the creation (nucleosynthesis) of chemical elements by nuclear fusion reactions within stars . Stellar nucleosynthesis has occurred since the original creation of hydrogen helium and lithium during the Big Bang.As a predictive theory it yields accurate estimates of the observed abundances of the elements .It explains why the observed abundances of elements change …
Stellar nucleosynthesis – Wikipedia
Abundance of the chemical elements – Wikipedia
Abundance of the chemical elements – Wikipedia
Fri Aug 12 2005 14:30:00 GMT-0400 (Eastern Daylight Time) · Supernova nucleosynthesis. Supernova nucleosynthesis is the nucleosynthesis of chemical elements in supernova explosions. In sufficiently massive stars the nucleosynthesis by fusion of lighter elements into heavier ones occurs during sequential hydrostatic burning processes called helium burning carbon burning oxygen burning and silicon burning in which the byproducts of one nuclear …
Helium (from Greek: ἥλιος romanized: Helios lit. ‘Sun’) is a chemical element with the symbol He and atomic number 2. It is a colorless odorless tasteless non-toxic inert monatomic gas the first in the noble gas group in the periodic table. Its boiling point is the lowest among all the elements .Helium is the second lightest and second most abundant element in the observable …
A synthetic element is one of 24 chemical elements that do not occur naturally on Earth: they have been created by human manipulation of fundamental particles in a nuclear reactor …