Which of the following statements related to the stages of evolution of the present atmosphere are correct? 1. The first stage is marked by the loss of primordial atmosphere. 2. In the second stage, the hot interior of the earth contributed to the evolution of the atmosphere. 3. Finally, the composition of the atmosphere was modified by the living world through the process of photosynthesis. Select the answer using the code given below:
- A.1 and 2 only
- B.1 and 3 only
- C.2 and 3 only
- D.1, 2 and 3
Correct answer
Explanation
The correct answer is D, 1, 2 and 3. All three statements describe, in the right order, the three stages through which the present atmosphere of the Earth evolved.
The early Earth had a primordial atmosphere of hydrogen and helium, which was stripped away by the solar wind; that loss is the first stage. In the second stage, gases such as water vapour, nitrogen, carbon dioxide, methane and ammonia came out of the hot interior through volcanic activity, a process called degassing. Water vapour condensed into rain and filled the oceans. In the third stage, life in the oceans began photosynthesis, which slowly added oxygen and changed the composition of the air.
A leaves out statement 3, although photosynthesis is what made the air rich in oxygen. B leaves out statement 2, the degassing stage. C leaves out statement 1, the loss of the primordial atmosphere, which began the whole process.
Exam tip: three stages of the atmosphere: loss of primordial gases, degassing from the interior, and modification by photosynthesis.
Practice Questions
View allD performs her train journey by the shortest route from Bengaluru to New Delhi. Which one of the following rivers will she not cross while performing the journey?
- A.Narmada
- B.Yamuna
- C.Godavari
- D.Krishna
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The shortest rail route from Bengaluru reaches Delhi from the south through Agra and Mathura, which lie on the western side of the Yamuna, so the train never has to cross that river.
Read the full explanation →In India, the period of steady population growth refers to the decade(s) of:
- A.1981-2011
- B.1951-1981
- C.1921-1951
- D.1911-1921
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In the standard division of India's population history, the three decades from 1921 to 1951 are called the period of steady population growth.
Read the full explanation →Consider the following statements with reference to earthquakes:
1. Collapse earthquakes are most common.
2. Tsunamis are waves generated by the tremors and not an earthquake in itself.
3. High magnitude earthquakes i.e. 8+ are quite rare whereas 'tiny' types occur almost every minute.
Which of the statements given above are correct?
- A.1 and 2 only
- B.1 and 3 only
- C.2 and 3 only
- D.1, 2 and 3
Show answer
Statement 1 is false because tectonic earthquakes, not collapse earthquakes, are the most common type. Earthquakes are grouped by cause: tectonic (sliding of rocks along a fault), volcanic, collapse (the roofs of underground mines or caverns falling in), explosion (from nuclear or chemical blasts) and reservoir-induced.
Read the full explanation →With reference to earthquakes, which of the following statements are correct?
1. Earthquakes largely occur along the converging plate boundaries.
2. Point of origin of earthquake in lithosphere is known as focus/hypocentre.
3. Intensity of earthquake decreases with distance from the epicentre.
4. Epicentre of earthquake always remains over continents only.
Select the correct answer using the code given below.
- A.1 and 2 only
- B.1, 2 and 3
- C.2 and 3 only
- D.1 and 4
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The first three statements are true, while statement 4 is false because many earthquakes have their epicentre under the sea.
Read the full explanation →National Disaster Management Authority is headed by
- A.the Prime Minister.
- B.the Home Minister.
- C.the President.
- D.the Health Minister.
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Under the Disaster Management Act, 2005, the Prime Minister is the ex officio chairperson of the National Disaster Management Authority (NDMA).
Read the full explanation →