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Greeley [361]
3 years ago
14

Early Earth was largely anoxic with very little oxygen present in the atmosphere. However, approximately 2 billion years ago, a

rise in atmospheric oxygen concentration was recorded in the geological record. This event, known as the great oxygenation event (GOE), was caused by small microorganisms (cyanobacteria) that likely carried out the process of ____________________ .
Chemistry
1 answer:
blagie [28]3 years ago
8 0

Answer:

Photosynthesis

Explanation:

Cyanobacteria were the first prokaryotic organisms capable of oxygen-evolving complex. Photosynthesis needs an electron source, in this case water (H2O). By photo-oxidation of the water, oxygen (O2) is released (and hydrogen taken).

This led to the accumulation of oxygen in the atmosphere where it got to similar concentrations as in these days.  

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Heats makes particles vibrate _________ (btw the options are in the pic)
Pie

Answer:ok so When heat is added to a substance, the molecules and atoms vibrate faster. As atoms vibrate faster, the space between atoms increases. The motion and spacing of the particles determines the state of matter of the substance. The end result of increased molecular motion is that the object expands and takes up more space.

hope this helps have a nice day❤️

Explanation:

8 0
2 years ago
Harry stores toxic chemical waste in a large steel tank that has only 15% of its volume underground. Jena lives in the wildernes
Anvisha [2.4K]

Answer:

Only Harry and Jena

Explanation:

Under federal regulations, an UST is any one or a combination of tanks such that the volume of an accumulation of regulated substances is 10% or more beneath the surface of the ground.

Any UST system holding a mixture of hazardous waste and other regulated substances are also are not covered by federal regulations regarding USTs.

Farm or residential tank of capacity more than 11 gallons used for storing motor fuel is covered by federal regulations regarding USTs.

According to the given question,

Only Harry and Jena are covered by federal regulations regarding USTs.

7 0
3 years ago
In which reaction does the oxidation number of hydrogen change? In which reaction does the oxidation number of hydrogen change?
dedylja [7]

<u>Answer:</u> The correct answer is 2Na(s)+2H_2O(l)\rightarrow 2NaOH(aq.)+H_2(g)

<u>Explanation:</u>

Oxidation number is defined as the number which is given to an atom when it looses or gains electron. When an atom looses electron, it attains a positive oxidation state. When an atom gains electron, it attains a negative oxidation state.

Oxidation state of the atoms in their elemental state is considered as 0. Hydrogen is present as gaseous state.

For the given chemical reactions:

  • <u>Reaction 1:</u>  2HClO_4(aq.)+CaCO_3(s)\rightarrow Ca(ClO_4)_2(aq.)+H_2O(l)+CO_2 (g)

Oxidation state of hydrogen on reactant side: +1

Oxidation state of hydrogen on product side: +1

Thus, the oxidation state of hydrogen is not changing.

  • <u>Reaction 2:</u>  CaO(s)+H_2O(l)\rightarrow Ca(OH)_2(s)

Oxidation state of hydrogen on reactant side: +1

Oxidation state of hydrogen on product side: +1

Thus, the oxidation state of hydrogen is not changing.

  • <u>Reaction 3:</u>  HCl(aq.)+NaOH(aq.)\rightarrow NaCl(aq.)+H_2O(l)

Oxidation state of hydrogen on reactant side: +1

Oxidation state of hydrogen on product side: +1

Thus, the oxidation state of hydrogen is not changing.

  • <u>Reaction 4:</u>  2Na(s)+2H_2O(l)\rightarrow 2NaOH(aq.)+H_2(g)

Oxidation state of hydrogen on reactant side: +1

Oxidation state of hydrogen on product side: 0

Thus, the oxidation state of hydrogen is changing.

  • <u>Reaction 5:</u>  SO_2(g)+H_2O(l)\rightarrow H_2SO_3(aq.)

Oxidation state of hydrogen on reactant side: +1

Oxidation state of hydrogen on product side: +1

Thus, the oxidation state of hydrogen is not changing.

Hence, the correct answer is 2Na(s)+2H_2O(l)\rightarrow 2NaOH(aq.)+H_2(g)

6 0
3 years ago
In water, hydrochloric acid forms positive ______ ions and negative _______ ions
kondaur [170]

Answers:

1st: H30+

2nd: CI-

3 0
3 years ago
What has mass and takes up space?<br> A. matter<br> B. weight<br> C. volume<br> D. space
spayn [35]

Answer:

Matter is anything that has mass and takes up space.

<h3><u>PLEASE</u><u> MARK</u><u> ME</u><u> BRAINLIEST</u></h3>
7 0
2 years ago
Read 2 more answers
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