chemically stable substance
91mass spectrometry — or mass spectroscopy Analytic technique by which chemical substances are identified by sorting gaseous ions by mass using electric and magnetic fields. A mass spectrometer uses electrical means to detect the sorted ions, while a mass spectrograph …
92mental disorder — Any illness with a psychological origin, manifested either in symptoms of emotional distress or in abnormal behaviour. Most mental disorders can be broadly classified as either psychoses or neuroses (see neurosis; psychosis). Psychoses (e.g.,… …
93respiration, human — ▪ physiology Introduction the process by which oxygen is taken up and carbon dioxide discharged. The design of the respiratory system The human gas exchanging organ, the lung, is located in the thorax, where its delicate tissues are… …
94Helium — otherusesHelium (He) is a colorless, odorless, tasteless, non toxic, inert monatomic chemical element that heads the noble gas group in the periodic table and whose atomic number is 2. Its boiling and melting points are the lowest among the… …
95RNA world hypothesis — A comparison of RNA (left) with DNA (right), showing the helices and nucleobases each employs. The RNA world hypothesis proposes that life based on ribonucleic acid (RNA) pre dates the current world of life based on deoxyribonucleic acid (DNA),… …
96Color photography — Color film redirects here. For the motion picture equivalent, see Color motion picture film. A circa 1850 Hillotype photograph of a colored engraving. Long believed to be a complete fraud, recent testing found that Levi Hill s process did… …
97Abiogenic petroleum origin — is a largely abandoned hypothesis that was proposed as an alternative to theory of biological petroleum origin. It was relatively popular in the past, but it went largely forgotten at the end of the 20th century after it failed to predict the… …
98Prise de risque sida — Pour les articles homonymes, voir Prise de risque. Cet article présente les différents facteurs pouvant entraîner la prise de risque sexuelle et amener une personne à être contaminée par le virus du Sida. Différentes dimensions sont présentées,… …
99Alkane — Not to be confused with Alkene or Alkyne. Chemical structure of methane, the simplest alkane Alkanes (also known as paraffins or saturated hydrocarbons) are chemical compounds that consist only of hydrogen and carbon atoms and are bonded… …
100Noble gas — Group 18 Period 1 2 He 2 …
