Isotopes of carbon or any element
Answer:
B
[(0.75)^3(0.25)]÷[(0.50)^2(0.75)]
Explanation:
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Answer:
Octane - Formula: C8H^18 = Carbon^8 + Hydrogen^18
Explanation: Octane is a compound because there are 8 atoms of carbon and 18 atoms of hydrogen in one molecule of C8H18. There are also 8 moles of carbon and 18 moles of hydrogen.
Answer:
Catalysts allow chemical reactions to occur at temperatures at which the organism lives.
Explanation:
Catalysts are molecules that speeden the rate of chemical reaction by lowering the activation energy of the reaction. In a living system, the catalyst are ENZYMES, which help to hasten up many biochemical reactions.
Another function of catalyst in living systems is that it allows chemical reactions to occur at temperatures at which the organism lives.
Answer:
<em>Option A. It was delivered by comets that crashed into Earth's surface.</em>
Explanation:
<em><u>Uranium (U) is a chemical element with atomic number 92.</u></em>
<em />
<em>For many years, a large number of scientists have been studying the abundance and origin of the isotopes of uranium in Earth</em>. <u>According to some theories, the Earth's uranium was produced in one or more supernovae</u> (an explosive brightening of a star), in wich, the main process consists in the rapid capture of neutrons by seed nuclei at great rates. <u>Another theory proposes that uranium is created during the merger of two neutron stars</u> (neutron stars are very dense), because, when such dense bodies come closer together the gravitational force cause them to merge, producing huge amounts of hevy metals like uranium.
<u><em>Many analyses have been made of the uranium in rocks of the Earth. These measurements shows that the abundance of uranium is bigger in the crust and upper mantle of the Earth</em></u>.
So, knowing that Earth's uranium was produced through one of these processes, <u><em>the best answer is option A, the uranium was delivered by comets that crashed into Earth's surface.</em></u>
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