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Melamine / ˈmɛləmiːn / ⓘ is an organic compound with the formula C 3 H 6 N 6. This white solid is a trimer of cyanamide, with a 1,3,5-triazine skeleton. Like cyanamide, it contains 66% nitrogen by mass, and its derivatives have fire-retardant properties due to its release of nitrogen gas when burned or charred.
Earliest known life forms. Evidence of possibly the oldest forms of life on Earth has been found in hydrothermal vent precipitates. [1] The earliest known life forms on Earth may be as old as 4.1 billion years old (or Ga) according to biologically fractionated graphite inside a single zircon grain in the Jack Hills range of Australia. [2] The ...
At long irregular intervals, Earth's biosphere suffers a catastrophic die-off, a mass extinction, [9] often comprising an accumulation of smaller extinction events over a relatively brief period. [10] The first known mass extinction was the Great Oxidation Event 2.4 billion years ago, which killed most of the planet's obligate anaerobes.
Mineral evolution. Most minerals on Earth formed after photosynthesis by cyanobacteria (pictured) began adding oxygen to the atmosphere. Mineral evolution is a recent hypothesis that provides historical context to mineralogy. It postulates that mineralogy on planets and moons becomes increasingly complex as a result of changes in the physical ...
Genetic research indicates arrival of humans in Japan by 37,000 BP. Archeological remains at the Tategahana Paleolithic Site at Lake Nojiri have been dated as early as 47,000 BP. The earliest known remains of Cro-Magnon-like humans are radiocarbon dated to 43,000–46,000 BP, found in Bulgaria, Italy, and Great Britain.
The timeline of human evolution outlines the major events in the evolutionary lineage of the modern human species, Homo sapiens, throughout the history of life, beginning some 4 billion years ago down to recent evolution within H. sapiens during and since the Last Glacial Period . It includes brief explanations of the various taxonomic ranks in ...
The history of life on Earth traces the processes by which living and extinct organisms evolved, from the earliest emergence of life to the present day. Earth formed about 4.5 billion years ago (abbreviated as Ga, for gigaannum) and evidence suggests that life emerged prior to 3.7 Ga. [1] [2] [3] The similarities among all known present-day ...
De Boisbaudran found a new earth in erbia. [147] 18 Argon: 1894 Lord Rayleigh and W. Ramsay: 1894: Lord Rayleigh and W. Ramsay: They discovered the gas by comparing the molecular weights of nitrogen prepared by liquefaction from air and nitrogen prepared by chemical means. It is the first noble gas to be isolated.