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Tanzania [10]
3 years ago
9

How did oxygen come up to make 21% of the earth's present atmosphere?

Chemistry
1 answer:
MakcuM [25]3 years ago
4 0
Tiny organisms known as cyanobacteria, or blue-green algae.
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6. Which of the following statements correctly describes what happens to the diaphragm during an
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Answer is B.

As the diaphragm contracts and flattens, it increases the volume of the thorax where the lungs are located. This results in a decrease in pressure (Boyle’s Law, if you know it) that creates a pressure gradient from outside to inside. This is what causes air to move into the lungs.
3 0
3 years ago
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Elemental exonium (not a real element) consists of two major isotopes abundance mass 18% 98 amu 82% 112 amu what is the atomic w
pishuonlain [190]
In general chemistry, isotopes are a group of substances that belong to the same element. An element is characterized in the periodic table by their atomic number, which is the number of protons in an atom. Therefore, these substances have the same atomic numbers, but differ in mass numbers. Mass number is the sum of the number of protons and neutrons in the nucleus of an atom. 

To determine the atomic weight of an element, you take the average weight of all the existent isotopes of that said element. The calculation would require to multiply the exact mass of the isotope to its abundance. Then, sum them all up.

Atomic weight = 98(0.18) + 112(0.82)
Atomic weight = 109.48 amu
3 0
3 years ago
Which of the following best describes an advantage of genetic engineering?
amm1812

Answer:

d

Explanation:

d

4 0
3 years ago
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Chlorine has two isotopes, 35Cl and 37Cl; 75.77 % of chlorine is 35Cl and 24.23 % is 37Cl. The atomic mass of 35Cl is 34.969 amu
storchak [24]

Answer:

35.4528731 amu

Explanation:

To appropriately get the atomic mass unit of chlorine, we can get the answer using the masses from the isotopes. This can be obtained as follows. What we do is that we multiply the percentage compositions by the masses.

Now let’s do this.

[75.77/100 * 34.969] + [24.23/100 * 36.966]

= 26.4960113 + 8.9568618 = 35.4528731

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4 years ago
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Transgenetics

hope this helps!
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