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3 years ago

Which statements indicate what the fossil record suggests about evolution on Earth? Check all that apply.

Chemistry

2 answers:

Gennadij [26K]3 years ago

6 0

The following are the statements, which indicates that the fossil record suggests about evolution on Earth:

1. Humans have only recently existed on Earth.

2. The organisms originally lived only in Earth's water.

3. The plants did not have flowers when dinosaurs existed.

The fossil remains have been discovered in the rocks of all the ages. The simplest organisms fossils are witnessed in the oldest rocks, and the fossils of more composite species are found in the newest rocks. This supports the theory of evolution suggested by Darwin, according to which the simple life forms slowly gets evolved into more composite ones.

mafiozo [28]3 years ago

3 0

Answer:

100% correct answer

Humans have only recently existed on Earth.

Organisms originally lived only in Earth’s water.

Plants did not have flowers when dinosaurs existed.

Explanation:

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An atom has a mass number of 24 and 13 neutrons. what is the atomic number of this atom?

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do ityou times 24×13=312.

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3 years ago

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Answer:

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3 years ago

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Ethyl butyrate, CH3CH2CH2CO2CH2CH3, is an artificial fruit flavor commonly used in the food industry for such flavors as orange

SIZIF [17.4K]

Answer:

A. 10.0 grams of ethyl butyrate would be synthesized.

B. 57.5% was the percent yield.

C. 7.80 grams of ethyl butyrate would be produced from 7.60 g of butanoic acid.

Explanation:

$CH_3CH_2CH_2CO_2H(l)+CH_2CH_3OH(l)+H^+\rightarrow CH_3CH_2CH_2CO_2CH_2CH_3(l)+H_2O(l)$

Moles of butanoic acid = $\frac{7.60 g}{88 g/mol}=0.08636 mol$

According to reaction ,1 mole of butanoic acid gives 1 mol of ethyl butyrate,then 0.08636 mol of butanoic acid will give :

$\frac{1}{1}\times 0.08636 mol=0.08636 mol$ of ethyl butyrate

Mass of 0.08636 moles of ethyl butyrate =

0.08636 mol × 116 g/mol = 10.0 g

Theoretical yield = 10.0 g

Experimental yield = ?

Percentage yield of the reaction = 100%

$Yield\%=\frac{\text{Experimental yield}}{\text{Theoretical yield}}\times 100$

$100\%=\frac{\text{Experimental yield}}{10.0 g}\times 100$

Experimental yield = 10.0 g

10.0 grams of ethyl butyrate would be synthesized.

Theoretical yield of ethyl butyrate = 10.0 g

Experimental yield ethyl butyrate = 5.75 g

Percentage yield of the reaction = ?

$Yield\%=\frac{\text{Experimental yield}}{\text{Theoretical yield}}\times 100$

$=\frac{5.75 g}{10.0 g}\times 100=57.5\%$

57.5% was the percent yield.

Moles of butanoic acid = $\frac{7.60 g}{88 g/mol}=0.08636 mol$

According to reaction ,1 mole of butanoic acid gives 1 mol of ethyl butyrate,then 0.08636 mol of butanoic acid will give :

$\frac{1}{1}\times 0.08636 mol=0.08636 mol$ of ethyl butyrate

Mass of 0.08636 moles of ethyl butyrate =

0.08636 mol × 116 g/mol = 10.0 g

Theoretical yield = 10.0 g

Experimental yield = ?

Percentage yield of the reaction = 78.0%

$Yield\%=\frac{\text{Experimental yield}}{\text{Theoretical yield}}\times 100$

$78.0\%=\frac{\text{Experimental yield}}{10.0 g}\times 100$

Experimental yield = 7.80 g

7.80 grams of ethyl butyrate would be produced from 7.60 g of butanoic acid.

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3 years ago

As of right now, which of the following forms of nuclear power is the most feasible for human use?

nikitadnepr [17]

As of now, the nuclear fission is the most feasible energy source for human use. All the nuclear power plants are based on the controlled nuclear fission reaction, where the unstable nucleus is bombarded with high speed neutrons, thus, splitting the nucleus into stable ones and releasing huge amount of energy. The nuclear fusion requires very high temperature, the temperature equal's to that of the sun. Hence, it is not feasible right now. As the technology advances, we will see advancement in other form of energies.

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3 years ago

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This is the chemical formula for acetic acid (the chemical that gives the sharp taste to vinegar): An analytical chemist has det

murzikaleks [220]

Answer:

0.11 mol

Explanation:

<em>This is the chemical formula for acetic acid (the chemical that gives the sharp taste to vinegar): CH₃CO₂H. An analytical chemist has determined by measurements that there are 0.054 moles of oxygen in a sample of acetic acid. How many moles of hydrogen are in the sample?</em>

Step 1: Given data

Formula of acetic acid: CH₃CO₂H

Moles of oxygen in the sample of acetic acid: 0.054 moles

Step 2: Establish the appropriate molar ratio

According to the chemical formula of acetic acid, the molar ratio of H to O is 4:2.

Step 3: Calculate the moles of atoms of hydrogen

We will use the theoretical molar ratio for acetic acid.

0.054 mol O × (4 mol H/2 mol O) = 0.11 mol H

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2 years ago