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kherson [118]
3 years ago
12

More than 1000 different species of cichlid fish live in Lake Malawi in Africa. Scientists studied sediment records from the lak

e. They found that the water levels dropped more than 200 meters around 24 times. Which of the following is the best example of how a water level drop could have contributed to the evolution of new species?
A:The fish had to adapt to a lack of oxygen.

B:The fish had to adapt to changes in the air.

C:The fish had to adapt to changes in water pH and salt levels.

D:The fish had to adapt to the sediment in the lake bed.
Chemistry
2 answers:
8090 [49]3 years ago
6 0
A would be the correct answer for you........
Molodets [167]3 years ago
4 0
A is the correct answer
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Which substance is a gas at 20˚C and one atmosphere of pressure? A. C B. O3 C. Ca D. I2
jasenka [17]

Answer:

O3

Explanation:

The answer to the question is O3 .

Hope this helped! Have an amazing day :)

3 0
3 years ago
Describing physical and chemical changes:
svetoff [14.1K]
Physical: The chemist could try to bend it to find out how malleable it is. He could also try to pull it into wires to find out how ductile it is.

Chemical: The chemist could put the metal into contact with other substances to get an idea of how reactive it is, and he could try to burn it and find out how flammable it is.
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3 years ago
Commercial agriculture can often lead to water-quality problems. In one to two sentences, explain how two of those problems occu
anygoal [31]

Commercial agriculture can often lead to water-quality problems in the following ways:

  • The washing of fertilizers and pesticides into water bodies from farms.

<h3>What is water quality?</h3>

Water quality refers to the state of a water body that encompasses it's physical, chemical and biological characteristics.

The water quality of a water body is crucial to its suitability for domestic or drinking purpose.

Commercial agriculture greatly affects water quality in the following ways:

  • The washing of fertilizers and pesticides into water bodies from farms.

Learn more about water quality at: brainly.com/question/20848502

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4 0
2 years ago
The product of the nuclear reaction in which 40Ar is subjected to neutron capture followed by alpha emission is ________. The pr
Orlov [11]

Answer:

37S

Explanation:

Radioactivity is the spontaneous emission of particles and / or electromagnetic radiation by unstable atomic nuclei leading to their disintegration.

We have two main types of radioactivity: radioactive decay and artificial transmutation.

In radioactive decay ( natural radioactivity ), a naturally occurring radioactive element like Uranium-238 disintegrates or decays into more stable isotopes with the emission of particles and/or radiation.

23892U = 23490Th + 42He

Artificial transmutation is the collision of two particles where one particle captures the other used to bombard it. There is subsequent production of isotopes similar or different from the bombarded particle. Neutrons, alpha particles ( helium nucleus ), electrons, protons can be used to bombard elements.

147N + 42He = 178O + 11P

For the above question which is artificial transmutation, the reaction equation is

4018Ar + 10n = 3716S + 42He

So, the neutron capture by Argon-40 will produce a radioisotope Sulphur-37 with the emission of an alpha particle.

5 0
3 years ago
For the following reaction, 9.30 grams of glucose (C6H12O6) are allowed to react with 13.8 grams of oxygen gas. glucose (C6H12O6
amid [387]

Answer:

13.7 g of CO₂

Limiting reactant:  C₆H₁₂O₆

3.81 g of O₂

Explanation:

We convert the mass of the reactants to moles, in order to find out the limiting reactant and the excess reagent

9.30 g / 180 g/mol = 0.052 moles of glucose

13.8 g / 32 g/mol = 0.431 moles of oxygen

The equation is:  C₆H₁₂O₆(s) + 6O₂ (g) → 6CO₂ (g) + 6H₂O (l)

Ratio is 1:6. Let's consider this rule of three:

1 mol of glucose reacts with 6 moles of oxygen

Then, 0.052 moles of glucose must react with (0.052 . 6) /1 = 0.312 moles

We have 0.431 moles of oxygen and we only need 0.312 moles. This means that an amount of oxygen still remains after the reaction is complete:

0.431 - 0.312 = 0.119 moles. We convert the moles to mass:

0.119 mol . 32 g / 1mol = 3.81 g

In conclussion, the limiting reactant is the glucose.

6 moles of oxygen react with 1 mol of glucose

0.431 moles of O₂ will react with (0.431 . 1) /6 = 0.072 moles of glucose

We only have 0.052 moles, so it is ok to say, that glucose is the limiting cause we do not have enough glucose.

Let's verify, the maximum amount of carbon dioxide that can be formed:

1 mol of glucose can produce 6 moles of CO₂

Therefore 0.052 moles of glucose will produce (0.052 . 6) /1 = 0.312 moles

We convert the moles to mass → 0.312 mol . 44 g /1 mol = 13.7 g

6 0
3 years ago
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