XMLS.XMLSAssembly

99久久婷婷国产综合亚洲,国产做国产爱免费视频,极品少妇被弄得高潮不断,日韩亚洲欧美中文高清在线

Hydrogen
Hydrogen

Hydrogen

Chemical formula: H2, hydrogen is an extremely flammable, colorless, transparent, odorless and tasteless gas. Hydrogen is the densest gas known in the world, being only 1/14 as dense as air. At normal temperature and pressure, gaseous hydrogen does not react with most substances. However, hydrogen reacts catalytically with many acetylenes at higher pressures and moderate temperatures. The normal boiling point of liquid hydrogen is-252.8℃, which is the lowest temperature gas except helium.