a) Why oxygen exists in a fixed ratio 21% in the atmosphere? b) The role of the atmosphere on Earth. 相关知识点: 试题来源: 解析 a) 氧气在大气中以固定比例21%存在的原因主要是由于生物地球化学循环的平衡。植物和其他光合作用生物通过光合作用释放氧气,而动物和微生物通过呼吸作用消耗氧气。此外,...
No life exists (生存) on the moon as there is no water and no air.3. But on this question, the two leaders have very fundamental (根本的) differences.4. It was so unlike (不像) him to say that, in such a rude manner, that I was astonished.5. Pale wooden floors and plenty of...
It exists momentarily due to its high reactivity, quickly reacting to form molecular oxygen or ozone. 10 How do plants contribute to the presence of molecular oxygen? Plants release molecular oxygen into the atmosphere as a byproduct of photosynthesis. 10 What is molecular oxygen? Molecular oxygen...
Oxygen is a colourless gas that exists in large quantities in the air. All plants and animals need oxygen in order to live. e.g. The human brain needs to be without oxygen for only four minutes before permanent damage occurs. 人的大脑缺氧4分钟后便会造成永久性损伤。
Symbol O A nonmetallic element that exists in its free form as a colorless, odorless gas and makes up about 21 percent of the Earth's atmosphere. It is the most abundant element in the Earth's crust and occurs in many compounds, including water, carbon dioxide, and iron ore. Oxygen comb...
Each of these bacterial processes no doubt influenced the composition of the atmosphere as well as the extent of thermal trapping by greenhouse gases (Table 10.1). Though controversial, a dramatic reduction in atmospheric methane concentrations by aerobic methane oxidation has been proposed to account ...
Oxygen (O) is an odorless, colorless, gaseous elementthat belongs to group 16 (formerly group VI) of thePeriodic Table. It is the most abundant elementin the earth's crust (49.2% by weight), is present in theatmosphere (20% by volume) and is a constituent ofwater. It exists in three...
Johnson F S. The oxygen and carbon dioxide balance in the earth's atmosphere[A].Netherlands:Springer,1975.49-56.Johnson, Francis S.: ‘The Oxygen and Carbon Dioxide Balance in the Earth’s Atmosphere’, this volume, pp. 49–56.
Symbol O A nonmetallic element that exists in its free form as a colorless, odorless gas and makes up about 21 percent of the Earth's atmosphere. It is the most abundant element in the Earth's crust and occurs in many compounds, including water, carbon dioxide, and iron ore. Oxygen comb...
Since cyanobacteria began to photosynthesize and introduce the colorless and odorless gas oxygen into the earth's atmosphere some 2.5 billion years ago, human evolution has been intrinsically linked to this critical molecule. Initially, the electrophilic chemical properties of oxygen rendered it a ...