A. Oxygen B. Gold C. Water D. Helium 相关知识点: 试题来源: 解析 C。解析:化合物是由两种或两种以上不同元素组成的纯净物。水(H₂O)是由氢和氧两种元素组成的化合物。A选项氧气(O₂)是单质,由一种元素组成;B选项黄金(Au)是单质;D选项氦气(He)是单质,所以C正确。反馈...
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The liquid-drop model has been particularly successful in explaining details of the fission process and in evolving a formula for the mass of a particular nucleus as a function of its atomic number and mass number, the so-called semiempirical mass formula. Another model is the Fermi gas model...
Consider the substance: helium gas. Classify this substance as a pure substance or a mixture. Explain or prove your answer. What type of mixtures can be separated by centrifugation? Explain the term heterogeneous nucleation. What is the definition of a eutectic mixture?
(Li2O). Sometimes, a new compound might form when an element is exposed to an existing compound. For example, when pure elemental sodium (Na) is submerged into liquid water (H2O), a reaction occurs, resulting in the formation of sodium hydroxide (NaOH) and the release of hydrogen gas. ...
At least one gaseous precursor of the deposit to be made comprising an aluminum compound is brought by means of a carrier gas into contact with the surfaces of the part which is placed inside an enclosure. The carrier gas is selected from helium and argon and the pressure inside the ...
Although it was claimed that the balloons contained helium, additional research revealed that hydrogen or acetylene was used. The explosion was brought on by the balloons rubbing up against a lightbulb. Where Does Helium Come From? Natural gas resourcescontain the non-renewable compound helium, deriv...
1.Helium is gas which consists of one proton and one neutron. 2.Labor union is organization of workers formed to improve their economic status and working conditions. 3.White dwarf is star that is unusually faint given its extreme temperature. 4.Rice is cereal grain that usually requires subtr...
For volatile organic compounds (VOCs) to be released from the plant cell into the atmosphere, they have to cross the plasma membrane, the cell wall, and the cuticle. However, how these hydrophobic compounds cross the hydrophilic cell wall is largely unkn