2013 GS Paper I, all questions

UPSC Prelims 2013 · GS Paper I

Question 18: Geography

Consider the following :

  1. 1.Electromagnetic radiation
  2. 2.Geothermal energy
  3. 3.Gravitational force
  4. 4.Plate movements
  5. 5.Rotation of the earth
  6. 6.Revolution of the earth

Which of the above are responsible for bringing dynamic changes on the surface of the earth?

a1, 2, 3 and 4 only
b1, 3, 5 and 6 only
c2, 4, 5 and 6 only
d1, 2, 3, 4, 5 and 6

AnswerUPSC’s answer is (d).

Endogenic forces, such as geothermal energy and plate movements, build up and break the crust, while exogenic forces, driven by solar radiation and gravity, wear it down through weathering, erosion and deposition. Rotation of the earth shapes winds, currents and tides, and its revolution brings the seasons. All six therefore bring dynamic changes to the surface.

  • 1. Solar radiation drives weather and weathering.
  • 2. Geothermal energy drives volcanism and crustal movement.
  • 3. Gravity drives erosion, mass movement and running water.
  • 4. Plate movements cause mountains, quakes and ocean basins.
  • 5. Rotation affects winds, currents and tides.
  • 6. Revolution brings the seasons and their changes.

How you could have got this

  1. If you were sure statement 1 is correct, (c) goes: it leaves 1 out.

    What you needed to know: Solar radiation drives weather and weathering.

  2. Then, if you were sure statement 2 is correct, (b) goes: it leaves 2 out.

    What you needed to know: Geothermal energy drives volcanism and crustal movement.

  3. Then, if you were sure statement 5 is correct, (a) goes: it leaves 5 out.

    What you needed to know: Rotation affects winds, currents and tides.

Only (d) is left. You didn’t need statements 3, 4 or 6.

Which options go is worked out from UPSC’s key and the options, not by a model.

Why each option is right or wrong
  • (a) Wrong. It leaves out rotation and revolution, which also bring changes.
  • (b) Wrong. It leaves out geothermal energy and plate movements.
  • (c) Wrong. It leaves out electromagnetic radiation and gravitational force.
  • (d) Correct. All six processes change the surface.

Answer: UPSC’s key. Explanation: written by UPSC Grade, not by UPSC.

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Source: UPSC, Civil Services (Preliminary) Examination 2013, General Studies Paper I, Series A. The paper on upsc.gov.in.