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lisov135 [29]
4 years ago
8

What is thought to have caused the mass extinction at the end of the Cretaceous Period?

Biology
1 answer:
My name is Ann [436]4 years ago
8 0
It was believed that a asteroid hit the Earth (specifically Mexico) when the asteroid hit it caused a freezing darkness due to dust and debris being kicked up by the asteroid . The dust and debris blocked the sunlight causing a temperature drop.
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Under what circumstances should de-extinction be legal for scientists to attempt?
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Explanation:

in the circumstances in which the attempts do not contravene the ethical and judicial laws.

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When did grass evolve?
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Which characteristic of water allows its molecules to form hydrogen bonds?
a_sh-v [17]

Answer:

b. The water molecule is polar.

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5 0
3 years ago
Read 2 more answers
Of the following choices, what is the approximate LD50 of the least toxic substance? 20 mg/kg, 70 mg/kg, or 130 mg/kg
pychu [463]

The approximate LD50 of the least toxic substance will be 130 mg/Kg.

  • The dose necessary to cause the death of 50% of a population under test after a predetermined test period is known as the LD50 value for a drug.
  • Commonly used as a broad indicator of a substance's acute toxicity are LD50 values.
  • Greater toxicity is indicated by a lower LD50. A low LD50 of 500 mg/kg or less implies severe toxicity.
  • Moderate toxicity is indicated by an LD50 of 500 to 1,000 mg/kg. A modest toxicity level of 1,000 to 2,000 mg/kg is indicated.
  • The species is especially vulnerable to the poison if the LD50 is low. The lethal dose (LD50) of a specific poison might change significantly between several animal species.
  • Thus out of all the options, LD50 130 mg/kg will have the lowest toxicity and 20 mg/kg will be the highest.

learn more about LD50 here: brainly.com/question/24845532

#SPJ1

8 0
2 years ago
Describe the composition of the core of the Earth.
fgiga [73]
I believe it is the second one not 100% sure so don't blame me if you fail.
8 0
3 years ago
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