Which one of the following correctly explains the change in seasons on Earth ?
- A.Tilt of the Earth's axis
- B.Rotation of the Earth on its own axis
- C.Revolution of the Moon around the Sun
- D.Interaction of the Earth with other planets
Correct answer
Explanation
The correct answer is A, tilt of the Earth's axis. Because the axis is tilted, each hemisphere leans towards the Sun for part of the year and away from it for the rest, which brings the seasons.
The Earth's axis is tilted about 23.5° from the perpendicular to its orbit, and the axis points the same way in space throughout the year. As the Earth revolves around the Sun, the northern hemisphere tilts towards the Sun around 21 June, getting more direct rays and longer days, so it has summer. Around 22 December it tilts away and has winter, while the southern hemisphere has the opposite season. If there were no tilt, there would be almost no seasons.
B is wrong: rotation on the axis causes day and night, not the seasons.
C is wrong: the Moon revolves around the Earth, and its motion causes its phases and, with the Sun, the tides.
D is wrong: the pull of other planets is far too weak to cause the yearly cycle of seasons.
Exam tip: Rotation → day and night; revolution plus the 23.5° tilt → seasons; summer solstice 21 June, winter solstice 22 December.
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
Show answer
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.
Show answer
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 →