Consider the following statements: 1. The Earths magnetic field has reversed every few hundred thousand years. 2. When the Earth was created more than 4000 million years ago, there was 54% oxygen and no carbon dioxide. 3. When living organisms originated,

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Q: 42 (IAS/2018)
Consider the following statements:
1. The Earth’s magnetic field has reversed every few hundred thousand years.
2. When the Earth was created more than 4000 million years ago, there was 54% oxygen and no carbon dioxide.
3. When living organisms originated, they modified the early atmosphere of the Earth.
Which of the statements given above is/are correct?

question_subject: 

Geography

question_exam: 

IAS

stats: 

0,59,85,16,13,103,12

keywords: 

{'early atmosphere': [0, 0, 0, 1], 'earth': [0, 1, 1, 1], 'carbon dioxide': [2, 0, 5, 6], 'magnetic field': [0, 0, 0, 6], 'living organisms': [0, 0, 1, 0]}

The correct answer is 3, meaning that statements 1 and 3 are correct.

Statement 1 states that "The Earth’s magnetic field has reversed every few hundred thousand years." This is known to be a fact. Earth`s magnetic field does undergo what`s called geomagnetic reversals, where the North and South Magnetic Poles switch places, approximately every several hundred thousand years.

Statement 2 highlights that "When the Earth was created more than 4000 million years ago, there was 54% oxygen and no carbon dioxide." This isn`t accurate. The Earth`s early atmosphere wasn`t rich in oxygen. On the contrary, it was composed mainly of nitrogen, water vapor, and carbon dioxide. Oxygen started to build up in the atmosphere around 2.5 billion years ago, due to photosynthesis by early life forms.

Statement 3 points out that "When living organisms originated, they modified the early atmosphere of the Earth." This statement is true. As life began to evolve on Earth, organisms helped alter the makeup of the atmosphere, notably through photosynthesis which resulted in increased levels of oxygen.

Therefore, the correct options are 1 and 3.

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