UPSC Previous Year Questions (Prelims): Introduction to Earth & Universe | Geography for UPSC CSE PDF Download

Q.1. What explains the eastward flow of the equatorial countercurrent?      (2015 - I)
(a) The Earth's rotation on its axis
(b) Convergence of the two equatorial currents
(c) Difference in salinity of water 
(d) Occurrence of the belt of calm near the equator

Correct Answer is Option (a)
The Earth's rotation on its axis explains the eastward flow of the equatorial counter-current. If the earth would have been rotating east to west, the piled-up water would have come down on the west side. Therefore, essentially it's the earth's rotation that explains the eastward flow of equatorial counter current.

Q.2. "Each day is more or less the same, the morning is clear and bright with a sea breeze; as the Sun climbs high in the sky, heat mounts up, dark clouds form, then the rain comes with thunder and lightning. But rain is soon over." Which of the following regions is described in the above passage?        (2015 - I) 
(a) Savannah 
(b) Equatorial
(c) Monsoon
(d) Mediterranean

Correct Answer is Option (b)
The passage points out the equatorial region.

Q.3. Consider the following pairs:        (2013 - I) 

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

Which of the above are responsible for bringing dynamic changes on the surface of the earth?
(a) 1, 2, 3 and 4 only 
(b) 1, 3, 5 and 6 only
(c) 2, 4, 5 and 6 only 
(d) 1, 2, 3, 4, 5 and 6

Correct Answer is Option (d)
From electromagnetic radiation to the revolution of the earth, everything is responsible for bringing dynamic changes to the surface of the earth. For example, Electromagnetic radiation brings changes in the field of microwaves, wavelengths of radio, UV rays, infrared rays, X rays, and gamma rays. Geothermal energy is the heat received from the earth’s core. This heat continuously flows outward. It transfers to the surrounding layers of rock, the mantle. When temperature and pressure become very high some mantle rocks melt becoming magma.  It then either comes out as lava or heats up the nearby rocks and water which comes out as hot springs or geysers. Gravitational force is constantly working on all physical bodies. It is giving weights to objects with mass and causes them to fall to the ground when dropped. Plate movement is a dynamic change on the surface of the earth. It explains many aspects of the interrelationship of volcanoes, earthquakes, climate change, and the evolution of life itself. Everything about our planet is related either directly or indirectly to plate tectonics. Rotation causes day and night. Revolution causes seasons, change in the length of day and night.

Q.4. On the planet earth, most of the freshwater exists as ice caps and glaciers. Out of the remaining freshwater, the largest proportion      (2013 - I) 
(a) is found in the atmosphere as moisture and clouds
(b) is found in freshwater lakes and rivers
(c) exists as groundwater 
(d) exists as soil moisture

Correct Answer is Option (c)
Out of all the water on Earth, saline water in oceans, seas, and saline groundwater make up about 97%  of it. Only 2.5 - 2.75% is fresh water, including 1.75-2%  frozen in glaciers, ice, and snow, 0.5 - 0.75%  as fresh groundwater and soil moisture, and less than 0.01%  of it as surface water in lakes, Swamps, and rivers.

Q.5. Variations in the length of daytime and nighttime from season to season are due to      (2013 - I)
(a) the earth’s rotation on its axis 
(b) the earth’s revolution around the sun in an elliptical manner
(c) latitudinal position of the place
(d) revolution of the earth on a tilted axis.

Correct Answer is Option (d)
Variations in the length of daytime and nighttime from season to season are due to the revolution of the earth on a tilted axis.

Q.6. Consider the following factors:         (2012 - I) 

1. Rotation of the Earth 
2. Air pressure and wind 
3. Density of ocean water 
4. Revolution of the Earth 

Which of the above factors influence the ocean currents? 
(a) 1 and 2 only
(b) 1, 2 and 3
(c) 1 and 4
(d) 2, 3 and 4

Correct Answer is Option (b)

1. Rotation of the Earth
2. Air pressure and wind
3. Density of ocean water. 

Revolution has no impact on ocean currents.

Q.7. Which of the following is/are cited by the scientists as evidence/evidences for the continued expansion of the universe?       (2012 - I)

1. Detection of microwaves in space  
2. Observation of redshift phenomenon in space 
3. Movement of asteroids in space 
4. Occurrence of supernova explosions in space

Select the correct answer using the codes given below:
(a) 1 and 2
(b) 2 only
(c) 1, 3 and 4 
(d) None of the above can be cited as evidence

Correct Answer is Option (a)
The cosmic microwave background (CMB) is the thermal radiation left over from the "Big Bang". The CMB has well explained as radiation left over from an early stage in the development of the universe and its discovery is considered a landmarks test of the Big Bang model of the universe. Redshift and Blueshift describe how light changes as objects in space (such as stars or galaxies) move closer or farther away from us. The concept is key to charting the universe's expansion.

Q.8. What is the difference between asteroids and comets?       (2011 - I)

1. Asteroids are small rocky planetoids, while comets are formed of frozen gases held together by rocky and metallic material. 
2. Asteroids are found mostly between the orbits of Jupiter and Mars, while comets are found mostly between Venus and Mercury. 
3. Comets show a perceptible glowing tail, while asteroids do not.  

Which of the statements given above is/are correct?
(a) 1 and 2 only 
(b) 1 and 3 only
(c) 3 only
(d) 1, 2 and 3

Correct Answer is Option (b)
Comets found beyond Nepture i.e. Kuiper belt. Asteroids are tiny planetary bodies revolving around the sun between the orbits of Jupiter and Mars. While comets are made up of small icy particles and Neteoric fragments.

Q.9. Consider the following statements:       (2010) 

1. On the planet Earth, the freshwater available for use amounts to about less than 1% of the total water found. 
2. Of the total freshwater found on the planet Earth 95% is bound up in polar ice caps and glaciers. 

Which of the statements given above is/are correct?
(a) 1 only 
(b) 2 only
(c) Both 1 and 2
(d) Neither 1 nor 2

Correct Answer is Option (a)
On the earth, the freshwater available for use amounts to about less than 1% of the total water, and its 68.7% is bound up in polar ice and glaciers.

Q.10. In the structure of planet Earth, below the mantle, the core is mainly made up of which one of the following?     (2009) 
(a) Aluminium 
(b) Chromium
(c) Iron
(d) Silicon

Correct Answer is Option (c)
The core of the earth is made up of nickle and iron.

Q.11. Which one of the following planets has the largest number of natural satellites or moons?       (2009) 
(a) Jupiter
(b) Mars
(c) Saturn 
(d) Venus

Correct Answer is Option (a)
Jupiter has maximum moons accounting for 63 whereas Satun has 61, Mars has 2 and Venus has none.

Q.12. In order of their distances from the Sun, which of the following planets lie between Mars and Uranus?       (2008) 
(a) Earth and Jupiter
(b) Jupiter and Saturn
(c) Saturn and Earth 
(d) Saturn and Neptune

Correct Answer is Option (b)
Jupiter and Saturn are located between Mars and Uranus.

Q.13. What is the average distance (approximate) between the sun and the earth?      (2007)
(a) 70 × 105 km
(b) 100 × 105 km
(c) 110 × 106 km
(d) 150 × 106 km

Correct Answer is Option (d)
The actual average distance between the sun and the earth is 152 × 106 km which is near 150 × 106 km.

Q.14. Assertion (A): To orbit around the Sun the planet Mars takes lesser time than the time taken by the earth. 
Reason (R): The diameter of the planet Mars is less than that of earth.      (2006)
(a) Both ‘A’ and ‘R’ are individually true and ‘R’ is the correct explanation of ‘A’.
(b) Both ‘A’ and ‘R’ are individually true but ‘R’ is not the correct explanation of ‘A’.
(c) ‘A’ is true but ‘R’ is false.
(d) ‘A’ is false but ‘R’ is true.

Correct Answer is Option (d)
A is incorrect as the mars revolution around the sun takes 1.88 years of Earth's revolution. The diameter of the earth is almost double to the diameter of mars.

Q.15. Consider the following statements:        (2005) 

1. The Axis of the earth's magnetic field is inclined at 23 and a half to the geographic axis of the earth. 
2. The earth's magnetic pole in the Northern Hemisphere is located on a Peninsula in Northern Canada. 
3. The earth's magnetic equator passes through Thumba in South India. Which of the statements given above is/are correct? 

(a) 1, 2 and 3
(b) 2 and 3 
(c) 2 only
(d) 3 only

Correct Answer is Option (b)
Earth's magnetic field is inclined between –90° to 90°. In the northern hemisphere, it points downwards and upward in the southern hemisphere.

Q.16. Assertion (A): Th e same face of the moon is always presented to the earth. 
Reason (R): The moon rotates about its own axis in 23 and half days which is about the same time that it takes to orbit the earth.     (2005)
(a) Both A and R are true and R is the correct explanation of A
(b) Both A and R are true but R is NOT a correct explanation of A
(c) A is true but R is false
(d) A is false but R is true

Correct Answer is Option (c)
The moon rotates about its own axis in 27.322 days. When the Moon first formed, its rotational speed and orbit were very different than they are now.  Over time, the Earth's gravitational field gradually slowed the Moon's rotation until the orbital period and the rotational speed stabilized, making one side of the moon always face the Earth.

Q.17. Among the following which planet takes maximum time for one revolution around the Sun?       (2003)
(a) Earth
(b) Jupiter 
(c) Mars
(d) Venus

Correct Answer is Option (b)
Jupiter takes maximum time for one revolution i.e., 11 year 86 days. Mars take 687 days, Venus takes 267 days.

Q.18. Which one of the following stat ements is correct with reference to our solar system?       (2002)
(a) The earth is the densest of all the planets in our solar system
(b) The predominant element in the composition of earth is silicon
(c) The sun contains 75 percent of the mass of the solar system
(d) The diameter of the sun is 190 times that of the earth

Correct Answer is Option (a)
The earth is the densest of all the planet. Density of Earth is 5.52, Venus–5.50, Mercury 5.27, Mars – 3.95, Jupiter and Saturn – 0.69, Uranus – 1.27

Q.19. If the stars are seen to rise perpendicular to the horizon by an observer, he is located on the:     (2001) 
(a) Equator
(b) Tropic of Cancer
(c) South Pole
(d) North Pole

Correct Answer is Option (a)
If the stars are seen to rise perpendicular to the horizon by an observer then the observer is at the equator because the celestial equator is an imaginary circle around the sky directly above the earth's equator. It is always 90º from the pole. All the stars rotate in a path that is parallel to the celestial equator.

Q.20. Who amongst the following was the first to state that the earth was spherical?       (2001)
(a) Aristotle
(b) Copernicus 
(c) Ptolemy
(d) Strabo

Correct Answer is Option (a)
Aristotle in 340 B.C first stated that the earth was spherical in his book “On the Heaven”

Q.21. Which one of the following scholars suggested the earth's origin from gases and dust particles?      (1999)
(a) James Jeans
(b) H. Alfven
(c) F. Hoyle
(d) O. Schmidt

Correct Answer is Option (d)
O. Schmidt in 1943 gave Interstellar Dust Hypothesis for the origin of the earth and solar system.

Q.22. Consider the following statements regarding asteroids:      (1998) 

1. Asteroids are rocky debris of varying size orbiting the sun 
2. Most of the asteroids are small but some have diameter as large and 1000 km 
3. The orbit of asteroids lies between the orbits of Jupiter and Saturn 

Of these statements: 
(a) 1, 2 and 3 are correct
(b) 2 and 3 are correct
(c) 1 and 2 are correct
(d) 1 and 3 are correct

Correct Answer is Option (c)
The asteroids are group of small pieces of rocky debris of different sizes. Some asteroids are small and some asteroids even have diameter 1000 km. The asteroids revolve between Mars and Jupiter.

Q.23. Which one of the following conditions is most relevant for the presence of life on Mars?        (1997)
(a) Atmospheric composition
(b) Thermal conditions 
(c) Occurrence of ice caps and frozen water
(d) Occurrence of ozone

Correct Answer is Option (c)
Mars is the only planet with similar day time temperatures and an atmosphere similar to earth. The most relevant condition for presence of life on Mars is occurrence of ice caps and frozen water.

Q.24. Which one of the following stars is nearest to the Earth?   (1997)
(a) Polaris
(b) Alpha Centauri
(c) Sun
(d) Sirius

Correct Answer is Option (c)
Sun is the star nearest to the earth. It is 150 million kilometer away from earth. Sun has temperatures of over 15 million ºC.