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matrenka [14]
3 years ago
11

After Earth formed, the emerging biosphere had several effects on Earth’s lithosphere. For example, rocks and minerals showed ev

idence of
A.cobustion B.oxidation C.fossilization D.respiration caused by the presence of oxygen in air. In a second example, A. minerals B.organisms C.carbon dioxide D.sunlight actually created new rock after being dissolved in water or buried underground.
Chemistry
1 answer:
kogti [31]3 years ago
3 0

The answer is; B

Initially, the earth’s atmosphere was mainly filled with carbon dioxide and methane. However, with the evolution of photosynthetic organisms, the composition of the atmosphere changed to be mainly oxygen. This geological time is referred to as the great oxygenation event. The high oxygen levels resulted in oxidation of most the upper lithosphere.  

The answer is; B

During this time, the organism on earth began to evolve and live on land. Therefore these geologic events are marked by fossilized of dead primitive organisms such as archaebacteria within the early rocks

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In a reaction vessel, 17.6 g of solid chromium(III) oxide, Cr2O3, was allowed to react with excess carbon tetrachloride in the f
notsponge [240]

Answer:

72.53% is the yield of CrCl3

Explanation:

Given

Reaction:

Cr2O3(s) + 3 CCl4(l) → 2 CrCl3(s) + 3 COCl2(aq)

CCl4 is in excess and 17.6g  Cr2O3 present

The reaction yields 26.6g of CrCl3

To Find:

% yields of the reaction

Also given

Molar mass of CrCl3 = 158.35g/mol

Molar mass of Cr2O3 = 152.00 g/mol

By the stoichiometry of the reaction

1 mole of Cr2O3 gives  2 moles of CrCl3

0r

1 x1 52 g of Cr2O3 gives 2x 158.35 g of CrCl3

= 1 52 g of Cr2O3 gives 316.70 g of CrCl3

    17.6 g of Cr2O3 gives  (17.6÷152) × 316.70 g CrCl3

= 36.67 g CrCl3

but actual yield is only 26.6g

so % yield is (26.6 ÷÷ 36.67) × 100

= 72.53% is the yield of CrCl3

8 0
3 years ago
Which state removed a physician's license to practice medicine.
skad [1K]
Most of our data are based on published information from the Association of American Medical Colleges, the Educational Council for Foreign Medical Graduates, the American Board of Medical Specialties, and the National Resident Matching Program. Data on board-certified physicians were obtained from the Division of Survey and Data Resources of the American Medical Association and are not published elsewhere
i think thats right

4 0
3 years ago
Addition of water to an alkyne gives a keto‑enol tautomer product. Draw an enol that is in equilibrium with the given ketone
Marrrta [24]

Addition of water to an alkyne gives a keto‑enol tautomer product and that is the product changed into 2-pentanone, then the alkyne need to had been 1-pentyne. 2-pentyne might have given a combination of 2- and 3-pentanone.

<h3>What is the keto-enol means in tautomer?</h3>

They carries a carbonyl bond even as enol implies the presence of a double bond and a hydroxyl group. The keto-enol tautomerization equilibrium is depending on stabilization elements of each the keto tautomer and the enol tautomer.

  1. The enol that could provide 2-pentanone might had been pent-1- en - 2 -ol. Because an equilibrium favors the ketone so greatly, equilibrium isn't an excellent description.
  2. If the ketone have been handled with bromine, little response might be visible because the enol content material might be too low.
  3. If a catalyst have been delivered, NaOH for example, then formation of the enolate of pent-1-en - 2 - ol might shape and react with bromine.
  4. This might finally provide a bromoform product. Under acidic conditions, the enol might desire formation of the greater substituted enol constant with alkene stability.

7 0
2 years ago
10g of a non-volatile and non-dissociating solute is dissolved in 200g of benzene.
ehidna [41]

<u>Answer: </u>The molar mass of solute is 115 g/mol.

<u>Explanation:</u>

Elevation in the boiling point is defined as the difference between the boiling point of the solution and the boiling point of the pure solvent.

The expression for the calculation of elevation in boiling point is:

\text{Boiling point of solution}-\text{boiling point of pure solvent}=i\times K_b\times m

OR

\text{Boiling point of solution}-\text{Boiling point of pure solvent}=i\times K_f\times \frac{m_{solute}\times 1000}{M_{solute}\times w_{solvent}\text{(in g)}} ......(1)

where,

Boiling point of pure solvent (benzene) = 80.10^oC

Boiling point of solution = 81.20^oC

i = Vant Hoff factor = 1 (for non-electrolytes)

K_b = Boiling point elevation constant = 2.53^oC/m

m_{solute} = Given mass of solute = 10 g

M_{solute} = Molar mass of solute = ? g/mol

w_{solvent} = Mass of solvent = 200 g

Putting values in equation 1, we get:

81.20-80.10=1\times 2.53\times \frac{10\times 1000}{M_{solute}\times 200}\\\\M_{solute}=\frac{1\times 2.53\times 10\times 1000}{1.1\times 200}\\\\M_{solute}=115g/mol

Hence, the molar mass of solute is 115 g/mol.

4 0
3 years ago
Research Hypatia's achievements in the world
Dimas [21]

Answer:

See explanation

Explanation:

Hypatia is popular for her work in mathematics. She also did some work in the area of astronomy. Her well know work in mathematics is her ideas about conic sections.

She was born the Theon of Alexandria and she was a professional mathematician in her life time.

She was the greatest mathematician of her time and she was telling leader of the Neoplatonist school of philosophy in Alexandria. By so doing, she conquered the culture of sexism in her time.

She was trained by her father in mathematics and eventually replaced him. She was the last major mathematician in the Alexandrian tradition.

6 0
3 years ago
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