Assertion : primitive atmosphere was reducing one i.e., without oxygen. Reason : In primitive atmosp

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6.Evolution

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Assertion : The primitive atmosphere was reducing one i.e., without oxygen.

Reason : In the primitive atmosphere, oxygen was involved in forming ozone

If both Assertion and Reason are correct and the Reason is a correct explanation of the Assertion.

If both Assertion and Reason are correct but Reason is not a correct explanation of the Assertion.

If the Assertion is correct but Reason is incorrect.

If both the Assertion and Reason are incorrect.

(AIIMS-2009)

Solution

The lightest atoms of nitrogen, carbon etc. formed the primitive atmosphere. Hydrogen atoms were most numerous and most reactive in primitive atmosphere. Hydrogen atoms combined with all oxygen atoms to form water leaving no free oxygen. Thus primitive atmosphere was reducing (without free oxygen) unlike the present oxidizing atmosphere (with free oxygen).

Formation of ozone layer is the consequence of modern oxidizing atmosphere having plenty of free oxygen. As more oxygen accumulated in the atmosphere (due to photosynthesis) ozone began to appear in the top layers.

Standard 12

Biology

Following are the two statements regarding the origin of life.

$(A)$ The earliest organisms that appeared on the earth were nongreen and presumably anaerobes.

$(B)$ The first autotrophic organisms were the chemoautotrophs that never released oxygen.Of the above statements which one of the following options is correct?

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(NEET-2016)

Which of the following breakup water into hydrogen and oxygen on early earth?

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Which theory arguments that life on earth came from outer space?

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$A$ : Theory of biogenesis explains that life arises from pre-existing life.
$R$ : Louis Pasteur finally disapproved the theory of spontaneous generation of life.

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The theory that living organisms on the earth came from outer space is based on the study of

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Assertion : The primitive atmosphere was reducing one i.e., without oxygen. Reason : In the primitive atmosphere, oxygen was involved in forming ozone

Solution

Similar Questions

Which of the following breakup water into hydrogen and oxygen on early earth?

Which theory arguments that life on earth came from outer space?

$A$ : Theory of biogenesis explains that life arises from pre-existing life. $R$ : Louis Pasteur finally disapproved the theory of spontaneous generation of life.

The theory that living organisms on the earth came from outer space is based on the study of

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Assertion : The primitive atmosphere was reducing one i.e., without oxygen.

Reason : In the primitive atmosphere, oxygen was involved in forming ozone

$A$ : Theory of biogenesis explains that life arises from pre-existing life.
$R$ : Louis Pasteur finally disapproved the theory of spontaneous generation of life.