World Geography


The Universe 


Q. No. 1. The “Big Bang Theory” is related to – (R.A.S./R.T.S.(Pre) 2007)

(a) Continental Drifts

(b) Origin of the Universe

(c) Origin of the Himalayas

(d) Eruption of Volcanoes

Answer: (b)

Explanation:

● The Big Bang Theory explains the origin and subsequent expansion of the Universe from an extremely hot and dense early state.

● The theory was proposed in its early form by Belgian astronomer and physicist Georges Lemaître (1894–1966), who suggested the idea of a “primeval atom” in 1927. The term “Big Bang” was later coined by British astronomer Fred Hoyle in 1949.

● According to the modern cosmological model, the Universe began expanding from an extremely hot and dense state about 13.8 billion years ago. It was not an explosion into pre-existing space; rather, space itself has been expanding.

● As the Universe expanded and cooled, galaxies and other large-scale structures gradually formed. Much later, stars, planets and systems such as the Solar System developed.

Hence, option (b) is correct.

Q. No. 2. The ''Big-Bang Theory'' explains the origin of – (U.P.P.C.S. (Pre) 2016)

(a) Mammals

(b) Ice-age

(c) Universe

(d) Ocean

Answer: (c)

Explanation:

● Origin of the Universe: The Big Bang Theory explains the origin and subsequent evolution of the Universe. Hence, option (c) Universe is correct.

● Beginning of Expansion: According to this theory, the Universe originated from an extremely hot and dense state and began expanding after a massive event known as the Big Bang.

● Age of the Universe: Based on the expansion rate of the Universe, this event is estimated to have occurred about 13.7–13.8 billion years ago, which is considered the approximate age of the Universe.

Hence, option (c) is correct.

Q. No. 3. The theory of continental drift was developed by- (67th B.P.S.C. (Pre) 2022)

(a) J.J. Wilson

(b) A. Wegener

(c) Du Toit

(d) H. Hess

(e) None of the above / More than one of the above.

Answer: (b)

Explanation:

Alfred Wegener proposed the Continental Drift Theory in 1912, later elaborated in his 1915 book The Origin of Continents and Oceans.

● He proposed that the present-day continents were once joined together into a single supercontinent called Pangaea, which subsequently fragmented into two major landmasses: Laurasia in the north and Gondwana in the south. These landmasses later further fragmented and drifted to form the present-day continents.

● Wegener supported his theory with evidence such as the jigsaw fit of continents, matching fossils, continuity of geological formations and evidence of past climates across now-separated continents.

Hence, option (b) is correct.

Q. No. 4. The milky way is classified as – (U.P.P.C.S. (Pre) 2001)

(a) Spiral Galaxy

(b) Electrical Galaxy

(c) Irregular Galaxy

(d) Round Galaxy

Answer: (a)

Explanation:

  1.  The Milky Way is a barred spiral galaxy, characterised by a central elongated bar surrounded by spiral arms. Therefore, option (a) is correct.
  2. Milky Way Galaxy: The Milky Way is the galaxy that contains our Solar System. It consists of billions of stars along with gas, dust and dark matter.
  3. Types of Galaxies: Galaxies are broadly classified into spiral, elliptical and irregular types based on their morphology. Spiral galaxies have a flattened disc with spiral arms, while elliptical galaxies are generally smooth and spheroidal, and irregular galaxies lack a well-defined structure.
  4. Barred Spiral Structure: Observations by NASA’s Spitzer Space Telescope in 2005 provided strong evidence for the presence of a central bar in the Milky Way, confirming its barred spiral nature.
  5. Universe and Galaxy Formation: The Universe is approximately 13.8 billion years old. Following the Big Bang, matter gradually formed large-scale structures through gravitational collapse and hierarchical structure formation, eventually giving rise to galaxies and galaxy clusters.

Q. No. 5. Time taken by the Sun to revolve around the centre of our galaxy is – (40th B.P.S.C. (Pre) 1995)

(a) 2.5 crores years

(b) 10 crores years

(c) 25 crores years

(d) 50 crores years

Answer: (c)

Explanation:

● Galactic Year: The Sun takes approximately 225–250 million years (22.5–25 crore years) to complete one revolution around the centre of the Milky Way Galaxy. This period is known as a Galactic Year or Cosmic Year.

● Sun as a Member of the Milky Way: The Sun is one of the billions of stars in the Milky Way Galaxy. It is located in the Orion Arm (Orion Spur) of the Milky Way and revolves around the Galactic centre along with other stars.

● Sun’s Location: The Sun is located approximately 8 kpc (about 26,000 light-years) from the centre of the Milky Way.

● Orbital Speed: The Sun moves around the Galactic centre at approximately 220 km/s (about 790,000 km/hour), although estimates vary.

● Therefore, the Sun takes approximately 22.5–25 crore years to complete one revolution around the Galactic centre.

Hence, option (c) is correct.

Q. No. 6. The colour of the star indicates its – (I.A.S. (Pre) 1994)

(a) Distance from Sun

(b) Lighting or glow

(c) Distance from Earth

(d) Temperature

Answer: (d)

Explanation:

● Star Colour and Temperature: The colour of a star indicates its surface temperature, not its distance from the Sun, distance from Earth, or brightness. 

● Hotter Stars: Stars with higher temperatures appear blue or blue-white, while cooler stars appear orange or red.

● The colour of a star is a direct indicator of its temperature; blue stars are the hottest, while red stars are comparatively cooler. Hence, option (d) Temperature is correct.

Q. No. 7. The limit beyond which stars suffer internal collapse is called : (U.P.P.C.S. (Pre) 1997)

(a) Chandrasekhar limit

(b) Eddington limit

(c) Hoyle limit

(d) Fowler limit

Answer: (a)

Explanation:

● Chandrasekhar Limit represents the maximum mass limit of a white dwarf, approximately 1.44 times the mass of the Sun, beyond which gravitational collapse occurs leading to further stellar evolution. Hence, option (a) Chandrasekhar limit is correct.

● Mass Limit of White Dwarf: This limit was explained by Subrahmanyan Chandrasekhar and is approximately 1.44 times the mass of the Sun. Beyond this limit, a star may collapse further to form a neutron star or black hole.

● Contribution of Chandrasekhar: Subrahmanyan Chandrasekhar was awarded the Nobel Prize in Physics in 1983 for his significant work on stellar evolution and the structure of stars.

Hence, option (a) is correct.

Q. No. 8. Black-hole is : (U.P.P.C.S. (Pre) 2019)

(a) a flight recorder in aeroplane

(b) a spot on the sun

(c) a place in Antarctica

(d) a collapsed star

Answer: (d)

Explanation:

● A black hole is an astronomical object or region of spacetime having an extremely strong gravitational field, from which nothing, not even light, can escape once it crosses the event horizon.

● A stellar-mass black hole can form when the core of a sufficiently massive star undergoes gravitational collapse, often associated with a supernova or core-collapse event.

● Therefore, among the given options, “a collapsed star” is the appropriate answer.

Hence, option (d) is correct.

Q. No. 9. Which is a celestial phenomenon occurring due to stars? (U.P.P.C.S. (Pre) 1997)

(a) Ozone hole

(b) Black Hole

(c) Rainbow

(d) Comet

Answer: (b)

Explanation:

A black hole is a region of spacetime with such strong gravitational pull that nothing, not even light, can escape from it. A stellar-mass black hole can form when the core of a sufficiently massive star undergoes gravitational collapse, often following a supernova or a related stellar-collapse event.

Hence, option (b) is correct.

Q. No. 10. The ''Black Hole Theory'' was propounded by : (U.P.P.C.S. (Pre) 1996)

(a) C.V. Raman

(b) H.J. Bhabha

(c) S.Chandrashekhar

(d) Hargovind Khurana

Answer: (c)

Explanation:

● Option (c): Subrahmanyan Chandrasekhar’s work on stellar evolution and the Chandrasekhar Limit contributed significantly to understanding the formation of black holes. Hence, option (c) is correct.

Q. No. 11. Assertion (A) : A black hole is an astronomical entity that cannot be seen by telescope.

Reason (R) : The gravitational field on a black hole is so strong that it does not allow even light to escape.

In the context of the above statements, which one of the following is correct :

(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 the correct explanation of (A).

(c) (A) is true, but R is false.

(d) (A) is false, but R is true.

(U.P.P.C.S.(Pre) 2003)

(U.P.P.C.S.(Pre) 2001)

Answer: (a)

Explanation:

●● Assertion (A): A black hole cannot be directly observed through ordinary optical telescopes, because light cannot escape from within its event horizon. However, black holes can be detected indirectly through their effects on nearby matter, stars and radiation. Hence, Assertion (A) is true.

● Reason (R): The gravitational field near a black hole is sufficiently strong that light cannot escape once it crosses the event horizon. Hence, Reason (R) is true.

● Relationship: The inability of light to escape from within the event horizon explains why a black hole itself cannot be directly seen in visible light. Therefore, (R) correctly explains (A).

Hence, option (a) is correct.

Q. No. 12. A 'black hole' is a body in space which does not allow any type of radiation to come out. This property is due to its – (I.A.S. (Pre) 2000)

(a) Very small size

(b) Very large size

(c) High density

(d) Very low density

Answer: (c)

Explanation:

A black hole is an astronomical object with an extremely strong gravitational field, such that no matter or electromagnetic radiation, including light, can escape from within its event horizon.

● The formation of a black hole occurs when a sufficiently large amount of mass is compressed into an extremely small region, resulting in an extreme concentration of mass and the formation of an event horizon.

● Therefore, among the given options, high density is the most appropriate answer. Hence, option (c) is correct.

Q. No. 13. A 'Supernova' is – (U.P. Lower Sub. (Mains) 2015)

(a) An asteroid

(b) A black hole

(c) A comet

(d) A dying star

Answer: (d)

Explanation:

Meaning of Supernova: A supernova is a powerful stellar explosion associated with the final stages of certain stars or the disruption of a white dwarf. It releases an enormous amount of energy and can briefly outshine an entire galaxy.

● Cause of Explosion: In a core-collapse supernova, a massive star exhausts its nuclear fuel, causing its core to collapse under gravity and triggering a catastrophic explosion. In a Type Ia supernova, a white dwarf in a binary system undergoes a thermonuclear explosion.

● The remnants of a core-collapse supernova may form a neutron star or, in sufficiently massive cases, a black hole.

Hence, option (d) A dying star is correct.

Q. No. 14. How many constellations are in our space? (44th B.P.S.C. (Pre) 2000)

(a) 87

(b) 88

(c) 89

(d) 90

Answer: (b)

Explanation:

● According to the International Astronomical Union (IAU), there are 88 officially recognised constellations covering the entire sky. Hence, option (b) 88 is correct.

● Constellation: A constellation is a defined region of the celestial sphere associated with a recognisable pattern of stars as seen from Earth. The apparent patterns are largely the result of the stars' positions as viewed from our perspective.

● The 88 constellations cover the entire celestial sphere and are divided between the Northern and Southern celestial hemispheres, with some constellations visible from both hemispheres depending on the observer's latitude and time of year.

● Examples include Ursa Major, Orion, Cassiopeia, Scorpius and Crux (Southern Cross).

Hence, option (b) is correct.

Q. No. 15. Which one of the following is not an Astronomical object? (I.A.S. (Pre) 1993)

(a) Pulsar

(b) Brittle star

(c) Black hole

(d) Quasar

Answer: (b)

Explanation:

● Pulsar: A pulsar is a highly magnetised, rapidly rotating neutron star that emits beams of electromagnetic radiation. As it rotates, these beams can be observed as regular pulses.

● Brittle Star: A brittle star is a marine echinoderm belonging to the class Ophiuroidea and is closely related to starfish. It is a terrestrial biological organism, not an astronomical object.Hence, option (b) is correct.

● Black Hole: A black hole is an astronomical object/region of spacetime with extremely strong gravity, from which nothing, including light, can escape once it crosses the event horizon. Stellar-mass black holes can form through the gravitational collapse of massive stars.

● Quasar: A quasar is an extremely luminous active galactic nucleus (AGN) powered by matter accreting onto a supermassive black hole at the centre of a galaxy.

Hence, option (b) is correct.

Q. No. 16. A group of stars arranged in a particular shape, is called– (U.P.P.C.S. (Pre) 2013)

(a) Milky Way

(b) Constellation

(b) Andromeda

(d) Solar system

Answer: (b)

Explanation:

● Milky Way: The Milky Way is the galaxy containing our Solar System, not a particular pattern of stars. Hence, option (a) is incorrect.

● Constellation: A constellation is a recognisable pattern or defined region of stars in the sky as viewed from Earth. Hence, option (b) is correct.

● Andromeda: The Andromeda Galaxy is a galaxy, not a constellation or a particular star pattern. Hence, option (c) is incorrect.

● Solar System: The Solar System consists of the Sun and the celestial bodies gravitationally bound to it, not a group of stars arranged in a particular pattern. Hence, option (d) is incorrect.

Hence, option (b) is correct.

Q. No. 17. Hubble space telescope has captured, for the first time, detailed image of the surface of a distant star. Name of the star : (U.P.P.C.S. (Pre) 1995)

(a) Virgo

(b) 70 Virgins

(c) Betelgeuse

(d) Big Dipper

Answer: (c)

Explanation:

● Betelgeuse is a red supergiant star located in the Orion constellation. It became the first star other than the Sun whose surface was resolved and imaged in detail by the Hubble Space Telescope.

Hence, option (c) is correct.

Q. No. 18. Consider the following Statements –(I.A.S. (Pre) 1996)

A person in spacecraft situated at the mid of earth and Sun will see that –

  1. Sky is black
  2. Stars do not twinkle
  3. The temperature outside the spacecraft is more than that of the earth surface.

Which of the following is true ?

(a) Only 3

(b) 1 and 2

(c) 1 and 3

(d) 1, 2 and 3

Answer: (b)

Explanation:

●: In space there is no atmosphere to scatter sunlight, therefore the sky appears black. Hence, statement 1 is correct.

● Stars do not twinkle in space because there is no atmosphere through which their light passes. Hence, statement 2 is correct.

● The temperature outside a spacecraft in space cannot simply be described as an atmospheric temperature because space is essentially a vacuum. An object's temperature depends on the balance between radiation absorbed and radiation emitted. Therefore, the statement that the temperature outside the spacecraft is necessarily higher than Earth's surface temperature is incorrect. Hence, statement 3 is incorrect. 

Hence, option (b) is correct.

Q. No. 19. "Light Year" is the unit of - (M.P.P.C.S. (Pre) 1994)

(a) Time

(b) Distance

(c) Luminosity

(d) None of these

Answer: (b)

Explanation:

A light-year is the distance travelled by light in vacuum in one year. One light-year is approximately 9.46 trillion km (5.88 trillion miles). It is a unit of distance, not time, and is commonly used to measure astronomical distances.

Hence, option (b) is correct.

Q. No. 20. If the stars are seen to rise perpendicular to the horizon by an observer, he is located on the – (I.A.S. (Pre) 2001)

(a) Equator

(b) Tropic of Cancer

(c) South Pole

(d) North Pole

Answer: (a)

Explanation:

  1. ● At the Equator, the celestial equator passes through the zenith and intersects the horizon at approximately 90°. Therefore, stars along the celestial equator appear to rise vertically (perpendicular to the horizon) in the east and set vertically in the west.
  2. ● At the North and South Poles, the celestial equator coincides approximately with the horizon, so stars appear to move parallel to the horizon rather than rising vertically.
  3. ● Therefore, an observer who sees stars rising perpendicular to the horizon is located at the Equator.
  4. Hence, option (a) is correct.

Q. No. 21. A person stood alone in a desert on a dark night and wanted to reach his village which was situated 5 km East of the point where he was standing. He had no instrument to find the direction but he located the pole star. The most convenient way now to reach his village is to walk in the (I.A.S. (Pre) 2012)

(a) Direction facing the pole star

(b) Direction opposite to the pole star

(c) Direction keeping the pole star to his left

(d) Direction keeping the pole star to his right

Answer: (c)

Explanation:

● The Pole Star indicates north direction. If a person keeps the Pole Star on his left, he moves towards east. Hence, option (c) is correct.

Q. No. 22. The group of stars that indicates the direction of pole, is (41st B.P.S.C. (Pre) 1996)

(a) Saptarishi

(b) Mrig

(c) Scorpio

(d) Taurus

Answer: (a)

Explanation:

●Saptarishi (Ursa Major/Great Bear): Saptarishi is a prominent group of seven stars in the constellation Ursa Major. The two stars at the outer edge of its bowl, called pointer stars, can be used to locate the Pole Star (Polaris), which indicates the north direction in the Northern Hemisphere. Hence, option (a) is correct.

Q. No. 23. Which one of the following is not related to space terminology? (U.P.P.C.S. (Pre) 1997)

(a) Telemetering

(b) Weightlessness

(c) Cislunar

(d) Byte

Answer: (d)

Explanation:

● Telemetering is related to transmission of data from spacecraft and satellites. Hence, option (a) is incorrect.

● Weightlessness is a condition experienced by astronauts in space due to microgravity. Hence, option (b) is incorrect.

● Cislunar refers to the region between Earth and the Moon’s orbit and is related to space studies. Hence, option (c) is incorrect.

● Byte is a computer terminology related to digital information storage and is not a space term. Hence, option (d) is correct.

Q. No. 24. The terms 'Event Horizon', 'Singularity', 'String Theory' and 'Standard Model' are sometimes seen in the news in the context of (I.A.S. (Pre) 2017)

(a) Observation and understanding of the Universe

(b) Study of the solar and the lunar eclipses

(c) Placing satellites in the orbit of the Earth

(d) Origin and evolution of living organisms on the Earth

Answer: (a)

Explanation:

  1. Event Horizon is the boundary around a black hole beyond which no information or event can escape and reach an outside observer.
  2. A gravitational singularity is a region where spacetime curvature becomes extremely large and classical general relativity breaks down. In black holes, the singularity lies within the event horizon, beyond which nothing, not even light, can escape.
  3. String Theory proposes that fundamental particles are not point-like objects but are made up of tiny one-dimensional vibrating strings.
  4. Standard Model of Particle Physics explains the known elementary particles and three fundamental forces — electromagnetic, strong nuclear, and weak nuclear forces (excluding gravity).
  5. Therefore, these terms are related to the observation and understanding of the Universe.
  6. Hence, option (a) is correct.

Q. No. 25. Which one of the following is not a natural unit of time? (Uttarakhand P.C.S. (Pre) 2016)

(a) Tropical year

(b) Lunar month

(c) Standard time

(d) Day

Answer: (c)

Explanation:

● Tropical year is based on Earth’s revolution around the Sun and is a natural astronomical time unit. Hence, option (a) is incorrect.

● Lunar month is based on the Moon’s revolution around Earth and is a natural astronomical period. Hence, option (b) is incorrect.

● Standard time is a human-defined system used for maintaining uniform time in a region. Hence, option (c) is correct.

● Day is based on Earth’s rotation and is a natural time unit. Hence, option (d) is incorrect.

Hence, option (c) is correct.

The Solar System


Q. No. 1. Which of the following does not belong to the solar system? 53rd to 55th B.P.S.C. (Pre) 2011

(a) Asteroids

(b) Comets

(c) Planets

(d) Nebula

Answer: (d)

Explanation:

● Asteroids are small rocky bodies orbiting the Sun and are part of the solar system. 

● Comets are celestial bodies consisting mainly of ice, dust and rocky material that revolve around the Sun. 

● Planets are major members of the solar system that revolve around the Sun. 

● Nebulae are large clouds of gas and dust present in in interstellar space and are not considered components of the solar system. 

Hence, option (d) is correct.

Q. No. 2. The scientist who first discovered that the earth revolves around the sun was –56th to 59th B.P.S.C. (Pre) 2015

(a) Newton

(b) Dalton

(c) Copernicus

(d) Einstein

Answer: (c)

Explanation:

● Nicolaus Copernicus, a Polish astronomer and mathematician, proposed the Heliocentric Theory of the solar system in his work Commentariolus (Little Commentary).

  1. The Heliocentric Theory states that the Earth and other planets revolve around the Sun.
  2. Hence, option (c) is correct.

Q. No. 3. Which one of the following statements is correct with reference to our solar system? I.A.S. (Pre) 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

Answer: (a)

Explanation:

  1. Earth has the highest average density among all eight planets of the Solar System, with a density of approximately 5.5 gm/cm³. The densities of other planets are: Mercury (5.4), Venus (5.2), Mars (3.9), Jupiter (1.3), Saturn (0.7), Uranus (1.3), and Neptune (1.6) gm/cm³.
  2. The major constituent element of Earth is Iron (32.07%), followed by Oxygen (30.12%) and Silicon (15.12%), making them the largest components of Earth's composition.
  3. The Sun contains about 99.8% of the total mass of the Solar System, making it the dominant celestial body in terms of mass.
  4. The diameter of the Sun is approximately 109.2 times greater than the diameter of Earth.

Hence, option (a) is correct.

Q. No. 4. The number of the planet in the solar system is –U.P.P.C.S. (Pre) 1992

(a) 7

(b) 9

(c) 12

(d) 21

Answer: (b)

Explanation:

  1. At the time of this 1992 examination, Pluto was classified as the ninth planet of the Solar System. Thus, the answer to the PYQ is 9.
  2.  In 2006, the International Astronomical Union (IAU) introduced a formal definition of a planet and classified Pluto as a dwarf planet.
  3. Therefore, the Solar System currently has eight recognised planets:
  4. Mercury → Venus → Earth → Mars → Jupiter → Saturn → Uranus → Neptune.
  5. Hence, option (b) is correct according to the classification prevailing when the question was asked.

Q. No. 5. Which of the given two planets are between Mars and Uranus in order of distance from the sun ? I.A.S. (Pre) 2008

(a) Earth and Jupiter

(b) Jupiter and Saturn

(c) Saturn and Earth

(d) Saturn and Neptune

Answer: (b)

Explanation:

  1. The order of planets based on their distance from the Sun is Mercury → Venus → Earth → Mars → Jupiter → Saturn → Uranus → Neptune.
  2. Between Mars and Uranus, the two planets located are Jupiter and Saturn.
  3. Hence, option (b) is correct.

Q. No. 6. Arrange the planets given below in order of increasing distance from sun ?U.P. Lower Sub. (Spl.) (Pre) 2003, U.P. Lower Sub. (Pre) 2002

  1. Pluto
  2. Earth
  3. Jupiter
  4. Uranus

Codes :

(a) 2,3,4,1

(b) 4,3,2,1

(c) 3,2,4,1

(d) 1,2,4,3

Answer: (a)

Explanation:

● The distance of planets from the Sun increases in the following order: Mercury → Venus → Earth → Mars → Jupiter → Saturn → Uranus → Neptune → Pluto (as per the older classification). Hence, among the given planets the correct order is Earth → Jupiter → Uranus → Pluto.

● Option (a): Represents the correct sequence 2,3,4,1. Hence, option (a) is correct.

Hence, option (a) is correct.

  1.  In 2006, the International Astronomical Union (IAU) introduced a formal definition of a planet and classified Pluto as a dwarf planet.
  2. Therefore, the Solar System currently has eight recognised planets.

Q. No. 7. The Earth is located between –U.P.P.C.S. (Mains) 2012

(a) Venus and Mars

(b) Mars and Jupiter

(c) Venus and Jupiter

(d) Mercury and Venus

Answer: (a)

Explanation:

● Option (a): The order of planets around Earth is Venus → Earth → Mars. Therefore, Earth lies between Venus and Mars. 

Hence, option (a) is correct.

Q. No. 8. Which is true about planets ? U.P. P.C.S. (Pre) 1992

(a) Planets are non-luminous bodies and don’t shine

(b) Planets shine though they are non-luminous bodies

(c) Planets do not shine though they are the luminous body

(d) Planets are the luminous body and also shine

Answer: (b)

Explanation:

● Planets do not produce their own light but shine by reflecting sunlight. Hence, option (b) is correct.

Q. No. 9. Match List-I with List-II and select the correct answer by using the codes given below the lists: I.A.S. (Pre) 1998

List-I (Special characteristic)

A. Smallest planet of the solar system

B. Largest planet of the solar system

C. Planet second to the sun in the solar system

D. Planet nearest to the sun

List- II (Name of the planet)

  1. Mercury
  2. Venus
  3. Jupiter
  4. Pluto
  5. Saturn

Code :

A B C D

(a) 2 3 5 1

(b) 3 5 1 2

(c) 4 1 2 3

(d) 4 3 2 1

Answer: (d)

Explanation:

● A–4: In 1998, when this question was asked, Pluto was classified as the smallest planet in the Solar System. However, in 2006, the International Astronomical Union (IAU) reclassified Pluto as a dwarf planet.

● B–3: Jupiter is the largest planet of the solar system. Hence, this pair is correct.

● C–2: Venus is the second planet from the Sun. Hence, this pair is correct.

● D–1: Mercury is the nearest planet to the Sun. Hence, this pair is correct.

● Therefore, the correct matching is 4,3,2,1.

Hence, option (d) is correct.

Q. No. 10. The planet nearest to the Sun is – U.P.P.C.S. (Mains) 2004

(a) Mercury

(b) Earth

(c) Venus

(d) Pluto

Answer: (a)

Explanation:

● Mercury is the first planet from the Sun and has the smallest orbital distance. Hence, option (a) is correct.

Q. No. 11. Which of the following pairs is not properly matched ? U.P.PC.S. (Mains) 2011

(a) The largest planet of the - Jupiter

Solar System

(b) The smallest planet of the - Mercury

Solar System

(c) The brightest planet of the - Venus

Solar System

(d) The slowest moving planet - Mars

of Solar System

Answer: (d)

Explanation:

● Jupiter is the largest planet in the solar system. Hence, option (a) is correctly matched.

● Mercury is the smallest planet among the eight recognised planets. Hence, option (b) is correctly matched.

● Venus is the brightest planet as seen from Earth due to its reflective clouds. Hence, option (c) is correctly matched.

● Neptune, not Mars, has the lowest average orbital speed among the eight planets, at about 5.4 km/s. It also has the longest orbital period, about 164.8 Earth years. Hence, option (d) is not properly matched.

Hence, option (d) is correct.

Q. No. 12. Arrange the following in decreasing order of size and select the correct answer from the codes given below : M.P.P.C.S. (Pre) 2008

  1. Jupiter
  2. Uranus
  3. Earth
  4. Saturn

Code :

(a) 1, 4, 3, 2

(b) 4, 1, 2, 3

(c) 1, 4, 2, 3

(d) 4, 1, 3, 2

Answer: (c)

Explanation:

  1. The planets arranged in descending order of size are: Jupiter > Saturn > Uranus > Earth.
  2. The complete decreasing order of planet sizes is: Jupiter, Saturn, Uranus, Neptune, Earth, Venus, Mars, and Mercury.
  3. Among the given planets, Jupiter is the largest, while Earth is smaller than Jupiter, Saturn, and Uranus.

Hence, option (c) is correct.

Q. No. 13. Which of the following is not a planet of Solar System? M.P.P.C.S. (Pre) 2010

(a) Mercury

(b) Florida

(c) Venus

(d) Saturn

Answer: (b)

Explanation:

● Florida is a state of the United States of America and is not a celestial body or planet. 

Hence, option (b) is correct.

Q. No. 14. 'The term 'Goldilocks Zone' is often seen in the news in the context of I.A.S. (Pre) 2015

(a) The limits of the habitable zone above the surface of the Earth

(b) Regions inside the Earth where shale gas is available

(c) Search for the Earth-like planets in outer space

(d) Search for meteorites containing precious metals

Answer: (c)

Explanation:

  1. The Goldilocks Zone refers to the habitable zone around a star where conditions are suitable for life. It is a region where the temperature is neither too hot nor too cold, allowing liquid water to exist on a planet.
  2. In astronomy, the Goldilocks Zone is also known as the circumstellar habitable zone. Scientists search this region to find Earth-like planets that may support life.
  3. In our solar system, Earth is located within the Goldilocks Zone because it has the right conditions for liquid water and life to exist.
  4. Therefore, the correct answer is (c) Search for the Earth-like planets in outer space.

Q. No. 15. Match list – I with list –II and choose the correct answer by using codes given below – U.P.P.C.S. (Pre) 1999

List – I

(A) Planet

(B) Satellite

(C) Comet

(D) Planetoid or artificial Satellite

List- II

  1. Moon
  2. Uranus
  3. Mariner
  4. Halley

Code :

A B C D

(a) 2 1 4 3

(b) 1 2 3 4

(c) 4 3 1 2

(d) 2 1 3 4

Answer: (a)

Explanation:

● A–2: Uranus is a planet of the solar system. Hence, this pair is correctly matched.

● B–1: Moon is a natural satellite of Earth. Hence, this pair is correctly matched.

● C–4: Halley is a famous comet that revolves around the Sun. Hence, this pair is correctly matched.

● D–3: Mariner refers to a spacecraft/artificial satellite series. Hence, this pair is correctly matched.

● The correct matching is 2,1,4,3.

Hence, option (a) is correct.

Q. No. 16. Which of the following statements are correct regarding the solar system? Chhattisgarh P.C.S. (Pre) 2020

I. Mercury is the hottest planet in the solar system

II. Ganymede, satellite of Saturn, is the largest satellite in the solar system

III. Neptune is surrounded by methane gas rings of sub-zero temperature

IV. Phobos and Deimos are two satellites of Mars

(a) Only I and II are correct

(b) Only II and III are correct

(c) Only III and IV are correct

(d) I, II, III and IV all are correct

Answer: (c)

Explanation:

  1. Venus is the hottest planet in the solar system, not Mercury, because its thick carbon dioxide atmosphere creates a strong greenhouse effect, raising surface temperatures to about 464°C.
  2. Ganymede is the largest satellite in the solar system, but it is a moon of Jupiter, not Saturn.
  3. Neptune has faint rings made of dust and ice particles, and its extremely cold atmosphere has sub-zero temperatures, with methane present in its atmosphere.
  4. Mars has two natural satellites—Phobos and Deimos. Therefore, the correct answer is (c) Only III and IV are correct.

Q. No. 17. Which is the chief heavenly body of solar system? 67th B.P.S.C. (Pre) (Re. Exam) 2022

(a) Earth

(b) Jupiter

(c) Saturn

(d) Sun

(e) None of the above / More than one of the above.

Answer: (d)

Explanation:

● The Sun is the central star of the solar system and contains about 99.8% of its total mass.

Hence, option (d) is correct.

The Sun 


Q. No. 1. Solar energy is due to – U.P.P.C.S. (Pre) 2006

(a) Ionization

(b) Nuclear Fusion

(c) Nuclear Fission

(d) Oxidation

Answer: (b)

Explanation:

  1. Solar energy is produced through the process of nuclear fusion occurring inside the Sun. Hence, the correct answer is (b) Nuclear Fusion.
  2. Nuclear fusion is a process in which two or more lighter atomic nuclei combine to form a heavier nucleus, releasing a large amount of energy, heat, and light.
  3. In contrast, nuclear fission involves the splitting of a heavy nucleus into two or more smaller nuclei along with energy release.
  4. In the Sun, hydrogen nuclei combine to form helium, releasing enormous energy that reaches Earth as solar radiation.

Hence, option (b) is correct.

Q. No. 2. Diamond Ring is a phenomenon observed : I.A.S. (Pre) 1996

(a) At the start of a total solar eclipse

(b) At the end of a total solar eclipse

(c) Only along the peripheral regions of the totality trail

(d) Only in the central regions of the totality trail

Answer: (c)

Explanation:

  1. The Diamond Ring effect is observed immediately before and after totality during a total solar eclipse and is associated with the beginning and end of the path of totality.
  2. It occurs when the last or first bright ray of sunlight passes through a valley on the Moon's irregular limb, while the solar corona remains visible around the Moon, producing the appearance of a bright “diamond” on a luminous ring.
  3. Thus, the phenomenon is observed near the peripheral regions of the totality trail.

Hence, option (c) is correct.

Q. No. 3. The solar eclipse occurs on - U.P.P.C.S. (Pre) 1991

(a) Quarter Moon day

(b) New Moon day

(c) Any day

(d) Full Moon day (Poornima)

Answer: (b)

Explanation:

  1. A solar eclipse occurs on the New Moon day (Amavasya) when the Moon comes between the Sun and the Earth. Hence, the correct answer is (b) New Moon day.
  2. During a solar eclipse, the Moon blocks the sunlight and casts its shadow on the Earth’s surface, causing the Sun to appear partially or completely covered.
  3. A solar eclipse can occur only during the New Moon phase, when the Sun, Moon, and Earth are aligned in a straight line.

Hence, option (b) is correct.

Q. No. 4. The Solar Eclipse achieves totality only in limited geographical regions because –

(a) The size of the shadow of the Moon on the Earth is small as compared to the cross section of the Earth.

(b) The Earth is not a smooth flat surface but has elevations and depressions.

(c) The trajectories of the Earth around the Sun and the Moon around the Earth are not perfect circles.

(d) Sun rays can reach most of the peripheral regions of the shadow of the Moon due to atmospheric refraction.

I.A.S. (Pre) 1993

Answer: (a)

Explanation:

  1. A total solar eclipse is visible only in limited geographical regions because the Moon’s shadow falling on the Earth is much smaller than the Earth’s cross-section. Hence, the correct answer is (a).
  2. A solar eclipse occurs when the Moon comes between the Earth and the Sun, blocking sunlight and casting its shadow on a small part of the Earth’s surface.
  3. Due to the small size of the Moon’s shadow, only those areas lying within the shadow path experience a total solar eclipse, while other regions observe a partial eclipse or no eclipse.

Hence, option (a) is correct.

Q. No. 5. Sun's halo is produced by the refraction of light in –I.A.S. (Pre) 2002

(a) Water vapour in stratus clouds

(b) Ice crystals in Cirro-Cumulus clouds

(c) Ice crystals in Cirrus clouds

(d) Dust particles in Stratus clouds

Answer: (c)

Explanation:

  1. Sun’s halo is produced due to the refraction of sunlight through ice crystals present in cirrus clouds. Hence, the correct answer is (c) Ice crystals in Cirrus clouds.
  2. A halo appears as a bright circular ring around the Sun when sunlight passes through the tiny ice crystals in high-altitude cirrus clouds and gets refracted.

Hence, option (c) is correct.

Q. No. 6. One Astronomical unit is average distance –Jharkhand P.C.S. (Pre) 2011

I.A.S. (Pre) 1998

(a) Between Earth and Sun

(b) Between Earth and Moon

(c) Between Jupiter and Sun

(d) Pluto and Sun

Answer: (a)

Explanation:

  1. One Astronomical Unit (AU) is the average distance between the Earth and the Sun. Hence, the correct answer is (a) Between Earth and Sun.
  2. The value of 1 AU is approximately 149.6 million km (or 150 million km), and it is used as a standard unit for measuring distances within the solar system.
  3. In other units, 1 AU = 149.59 × 10⁹ metres and 149.59 × 10¹² millimetres, representing the mean Earth–Sun distance.

Hence, option (a) is correct.

Q. No. 7. The average or mean distance between the earth and the sun is –I.A.S. (Pre) 1997

(a) 70 × 155 km

(b) 100 × 105 km

(c) 110 × 106 km

(d) 150 × 106 km

Answer: (d)

Explanation:

  1. The average (mean) distance between the Earth and the Sun is known as 1 Astronomical Unit (AU). Hence, the correct answer is (d) 150 × 10⁶ km.
  2. The value of 1 AU is approximately 149.6 million km or 149.598 × 10⁶ km, which represents the mean Earth–Sun distance.
  3. Astronomical Unit is used as a standard measure for calculating distances within the solar system.

Hence, option (d) is correct.

Q. No. 8. The earth is nearest to the sun on –U.P.P.S.C. (GIC) 2010

(a) 3rd January

(b) 4th July

(c) 22nd March

(d) 21st September

Answer: (a)

Explanation:

  1. The Earth is nearest to the Sun on 3rd/4th January, and this position is called Perihelion. Hence, the correct answer is (a) 3rd January.
  2. During Perihelion, the distance between the Earth and the Sun is minimum, approximately 147 million km.
  3. The opposite position is called Aphelion, which occurs around 4th July, when the Earth is farthest from the Sun (about 152 million km).

Hence, option (a) is correct.

Q. No. 9. Size of the Sun is how many times bigger than that of the earth ? M.P.P.C.S. (Pre) 2014

(a) 124 times

(b) 100 times

(c) 109 times

(d) 115 times

Answer: (c)

Explanation:

  1. The diameter of the Sun is about 109 times larger than the diameter of the Earth. Hence, the correct answer is (c) 109 times.
  2. According to NASA, the mean radius of the Sun is about 695,700 km, while the mean radius of the Earth is about 6,371 km, showing the vast difference in their sizes.

Hence, option (c) is correct.

Q. No. 10. Which of the following statements is true regarding earth movement? Jharkhand P.C.S. (Pre) 2021

  1. Earth rotates on its axis from west to east resulting into seasonal changes.
  2. Earth revolution around sun results into occurrence of day and night on earth.

(a) Both 1 and 2 are true

(b) Only 2 is true

(c) Both 1 and 2 are false

(d) Only 1 is true

Answer: (c)

Explanation:

● Earth rotates from west to east, but rotation causes day and night, not seasonal changes. Seasons occur due to Earth’s revolution around the Sun along with axial tilt. Hence, statement 1 is incorrect.

● Earth’s revolution around the Sun causes seasonal changes, not day and night. Day and night occur due to rotation of Earth on its axis. Hence, statement 2 is incorrect.

Hence, option (c) is correct.

Q. No. 11. The bright outer layer of the sun is known as : Uttarakhand P.C.S. (Pre) 2024

(a) Photosphere

(b) lonosphere

(c) Mesosphere

(d) Sunspots

Answer: (a)

Explanation:

  1. The Photosphere is the bright, visible surface of the Sun and is the innermost layer of its atmosphere.
  2. It lies above the Sun's convection zone and has a temperature of approximately 5,500°C (about 5,800 K).
  3. The chromosphere and corona lie above the photosphere and become particularly prominent during a total solar eclipse.

Hence, option (a) is correct.