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The Sun's photosphere consists mostly of hydrogen and helium; the helium abundance varies between about 10.3 and 10.5 depending on the phase of the solar cycle; [13] carbon is 8.47, neon is 8.29, oxygen is 7.69 [14] and iron is estimated at 7.62.
Lighters containing flammable gas 2.1: Lighter refills containing flammable gas not exceeding 4 fluid ounces (7.22 cubic inches) and 65 grams of flammable gas UN 1058: 2.2: Liquified gases, nonflammable charged with nitrogen, carbon dioxide, or air UN 1059? (UN No. no longer in use) UN 1060: 2.1: Methyl acetylene and propadiene mixtures ...
The gaseous state of water is lighter than air (density 0.804 g/L at STP, average molecular mass 18.015 g/mol) due to water's low molar mass when compared with typical atmospheric gases such as nitrogen gas (N 2). It is non-flammable and much cheaper than helium.
Helium is the least water-soluble monatomic gas, [96] and one of the least water-soluble of any gas (CF 4, SF 6, and C 4 F 8 have lower mole fraction solubilities: 0.3802, 0.4394, and 0.2372 x 2 /10 −5, respectively, versus helium's 0.70797 x 2 /10 −5), [97] and helium's index of refraction is closer to unity than that of any other gas. [98]
2 with n from 2 to 6 have been made by shooting electrons at a supersonically expanding mix of nitrogen and helium. [70] C 60 He + is formed by irradiating C 60 with 50eV electrons and then steering ions into cold helium gas. C 60 He + 2 is also known. [84]
The noble gases—including helium—can form stable molecular ions in the gas phase. The simplest is the helium hydride molecular ion, HeH +, discovered in 1925. [59] Because it is composed of the two most abundant elements in the universe, hydrogen and helium, it was believed to occur naturally in the interstellar medium, and it was finally ...
Atomicity is the total number of atoms present in a molecule of an element. For example, each molecule of oxygen (O 2) is composed of two oxygen atoms. Therefore, the atomicity of oxygen is 2. [1] In older contexts, atomicity is sometimes equivalent to valency. Some authors also use the term to refer to the maximum number of valencies observed ...
As a result, there is little mixing of fresh hydrogen into the core or fusion products outward. In higher-mass stars, the dominant energy production process is the CNO cycle, which is a catalytic cycle that uses nuclei of carbon, nitrogen and oxygen as intermediaries and in the end produces a helium nucleus as with the proton–proton chain. [22]