(C) Fifth Explanation: Earth is the largest of the inner planets, and the fifth largest planet of our solar system.

(B) Oblate spheroid Explanation: Earth is an oblate spheroid, meaning it is slightly flattened at the poles and bulging at the equator due to its rotation.

(C) 71% Explanation: Approximately 71% of Earth’s surface is covered by water, including oceans, seas, lakes, and rivers.

(B) Blue planet Explanation: Earth is called the "Blue Planet" because about 71% of its surface is covered by water, primarily in the form of oceans. The vast amount of water gives Earth its distinctive blue appearance when viewed from space.

(B) 8 minutes Explanation: It takes approximately 8 minutes and 20 seconds for sunlight to travel from the Sun to Earth, covering the distance of about 149.6 million km (93 million miles).

(A) 24 hours Explanation: Earth takes approximately 24 hours to complete one full rotation on its axis, which defines the length of a day. This rotation is responsible for the cycle of day and night.

(C) 365.25 days Explanation: It takes Earth approximately 365.25 days to complete one full revolution around the Sun. The extra 0.25 days accumulate over four years, leading to the addition of a leap day every fourth year, making that year 366 days long.

(C) 23.5 degrees Explanation: Earth's axis of rotation is tilted at an angle of approximately 23.5 degrees relative to its orbit around the Sun. This tilt is responsible for the changing seasons as Earth orbits the Sun.

(B) Perihelion Explanation: Perihelion is the point in Earth's elliptical orbit where it is closest to the Sun. This occurs around early January each year. Conversely, the point where Earth is farthest from the Sun is called aphelion.

(A) Aphelion Explanation: Aphelion is the point in Earth's elliptical orbit where it is farthest from the Sun. This typically occurs around early July, when Earth is about 152 million kilometers (about 94.5 million miles) from the Sun.

(A) Mount Everest Explanation: Mount Everest, located in the Himalayas, is the highest point on Earth, with a peak at 8,848 meters (29,029 feet) above sea level.

(D) Pacific Ocean Explanation: The Pacific Ocean is the largest and deepest ocean on Earth, covering more than 63 million square miles and containing more than half of the world's ocean water.

(A) Mariana Trench Explanation: The Mariana Trench, located in the western Pacific Ocean, is the deepest part of the world's oceans, reaching a maximum depth of about 36,000 feet (11,000 meters) at the Challenger Deep.

(B) Venus Explanation: Venus is the closest planet to Earth in terms of average distance. Although Mercury occasionally gets closer to Earth during its orbit, Venus is typically the nearest planet to us.

(C) Nitrogen Explanation: Nitrogen makes up about 78% of Earth's atmosphere, making it the most abundant gas. Oxygen is the second most abundant at about 21%.

(B) Feldspar Explanation: Feldspar is the most abundant mineral in Earth's crust, making up about 41% of it. It is a group of rock-forming minerals found in many types of rocks.

(C) Aluminium Explanation: Aluminium is the most abundant metal in Earth's crust, constituting about 8% of the Earth's solid surface. It is primarily found in the mineral bauxite.

(C) Iron Explanation: Earth's core is primarily composed of iron, along with some nickel. The inner core is solid, while the outer core is molten, generating Earth's magnetic field.

(B) The Moon Explanation: The Moon is Earth's only natural satellite. It orbits the Earth and is the fifth largest moon in the Solar System. The Moon plays a crucial role in affecting Earth's tides and has been the subject of human exploration.

(B) 4.5 billion years Explanation: Scientists estimate the age of the Earth to be approximately 4.5 billion years based on radiometric dating of rocks and meteorites.

(B) Geothermal heat Explanation: Geothermal heat, generated by the slow decay of radioactive isotopes in the Earth's interior, is the primary source of energy driving Earth's internal processes such as plate tectonics and volcanic activity.

(B) The Sun Explanation: The Sun provides the energy necessary for the water cycle, driving processes such as evaporation, condensation, and precipitation.

(A) Volcanic outgassing Explanation: The Earth's early atmosphere primarily evolved through outgassing, where gases trapped within the planet's interior were released during volcanic activity.

(A) Fossils Explanation: Fossils provide valuable evidence for Earth's geological history, helping scientists understand past environments, the evolution of life, and the changing Earth over time.

(A) Fossil records Explanation: Fossil records provide evidence of early life on Earth. Microbial fossils, stromatolites, and chemical signatures found in ancient rocks suggest the presence of early life forms.

(A) Tides Explanation: Tides are caused by the gravitational pull of the Moon and the Sun on Earth's oceans, leading to the rise and fall of sea levels at regular intervals.

(C) Earth's rotation on its axis Explanation: Day and night are caused by Earth's rotation on its axis. As Earth rotates, different parts of the planet are exposed to sunlight, resulting in day, while the parts facing away from the Sun experience night.

(B) The tilt of Earth's axis Explanation: Earth's seasons are primarily caused by the tilt of its axis, which is about 23.5 degrees. This tilt causes different parts of Earth to receive varying amounts of sunlight throughout the year.

(C) 150 million km Explanation: The average distance between Earth and the Sun is approximately 150 million km (about 93 million miles). This distance is also known as 1 Astronomical Unit (AU), which is a standard measure used to describe distances within our solar system.

(B) 380,000 km Explanation: The average distance between Earth and the Moon is approximately 380,000 km (about 238,855 miles). This distance varies slightly due to the elliptical shape of the Moon's orbit around Earth.

(C) 35,786 km Explanation: A geostationary satellite orbits the Earth at an altitude of approximately 35,786 km (22,236 miles) above the equator. This specific altitude allows the satellite to synchronize its orbit with the Earth's rotation, maintaining a fixed position relative to the surface.

(A) March 21 Explanation: The vernal equinox typically occurs around March 21. This equinox marks the beginning of spring in the Northern Hemisphere and autumn in the Southern Hemisphere, with nearly equal lengths of day and night.

(B) June 21 Explanation: The summer solstice in the Northern Hemisphere typically occurs around June 21. This date marks the longest day of the year and the beginning of summer, when the Sun is at its highest point in the sky at noon.

(B) June 21 Explanation: The winter solstice in the Southern Hemisphere typically occurs around June 21. On this date, the Southern Hemisphere experiences the shortest day and the longest night of the year, marking the beginning of winter.

(C) September 23 Explanation: The autumnal equinox typically occurs around September 23, marking the start of autumn in the Northern Hemisphere and spring in the Southern Hemisphere. On this day, the lengths of day and night are nearly equal.

(B) Amazon rainforest Explanation: The Amazon rainforest is one of the most biodiverse regions on Earth, home to an immense variety of plants, animals, and microorganisms, many of which are not found anywhere else.

(A) Latitude Explanation: Latitude is the primary factor determining a region's temperature and climate. Regions closer to the equator (low latitude) tend to be warmer, while regions closer to the poles (high latitude) tend to be cooler.

(C) Troposphere Explanation: The troposphere is the lowest layer of Earth's atmosphere and is where all weather phenomena, such as rain, snow, storms, and winds, occur. It extends up to about 8 to 15 km (5 to 9 miles) above the Earth's surface.

(B) Stratosphere Explanation: The ozone layer, which absorbs and scatters ultraviolet solar radiation, is located in the stratosphere, the second layer of Earth's atmosphere.

The Earth Facts | 50+ Important MCQ On The Blue Planet

41. In which layer of Earth’s atmosphere do auroras occur?

(A) Exosphere
(B) Stratosphere
(C) Mesosphere
(D) Thermosphere

(D) Thermosphere
Explanation: Auroras (Northern and Southern Lights) occur in the thermosphere, where charged particles from the Sun interact with Earth’s magnetic field.

42. Which layer of Earth’s atmosphere is most important for radio communication?

(A) Troposphere
(B) Stratosphere
(C) Ionosphere
(D) Mesosphere

(C) Ionosphere
Explanation: The ionosphere, part of the thermosphere, contains charged particles that reflect radio waves, making long-distance radio communication possible.

43. Which of the following is the most abundant greenhouse gas in Earth’s atmosphere?

(A) Carbon dioxide
(B) Methane
(C) Water vapor
(D) Nitrous oxide

(C) Water vapor
Explanation: Water vapor is the most abundant greenhouse gas in Earth’s atmosphere. It plays a crucial role in Earth’s climate and weather patterns, although carbon dioxide and methane are also significant contributors to the greenhouse effect.

44. Which layer of the atmosphere protects Earth from meteoroids?

(A) Troposphere
(B) Mesosphere
(C) Stratosphere
(D) Thermosphere

(B) Mesosphere
Explanation: The mesosphere burns up most meteoroids that enter Earth’s atmosphere, preventing them from reaching the surface.

45. In which layer of Earth’s atmosphere do commercial jets typically fly?

(A) Troposphere
(B) Stratosphere
(C) Mesosphere
(D) Thermosphere

(B) Stratosphere
Explanation: Commercial jets typically fly in the lower stratosphere to avoid turbulence and weather disturbances that are common in the troposphere.

46. What is the gravitational force at the centre of the Earth?

(A) Maximum
(B) Half of the surface gravity
(C) Zero
(D) Twice the surface gravity

(C) Zero
Explanation: At the centre of the Earth, the gravitational forces from all directions cancel each other out, resulting in zero net gravitational force. Therefore, an object at the exact center of the Earth would experience no gravitational pull.

47. Where the gravitational acceleration of the Earth is maximum?

(A) Centre
(B) Outer core
(C) Surface
(D) Mountain top

(C) Surface
Explanation: The maximum gravitational acceleration is found at the Earth’s surface. This value represents the acceleration due to gravity, indicating how quickly an object will accelerate towards the Earth when in free fall.

48. What is the primary cause of Earth’s magnetic field?

(A) Movement of the lithosphere
(B) Interaction of the solar wind with the atmosphere
(C) Convection currents in the outer core
(D) Rotation of the Earth

(C) Convection currents in the outer core
Explanation: Earth’s magnetic field is generated by convection currents of molten iron and nickel in the outer core, which create electric currents and produce the magnetic field.

49. What is the position of the Sun during an equinox?

(A) Directly over the Tropic of Cancer
(B) Directly over the Tropic of Capricorn
(C) Directly over the Equator
(D) At its highest point in the sky

(C) Directly over the Equator
Explanation: During an equinox, the Sun is positioned directly over the equator. This results in nearly equal lengths of day and night across the globe. Equinoxes occur twice a year, around March 21 (vernal equinox) and September 23 (autumnal equinox).

50. What occurs during an equinox?

(A) The Sun is directly overhead at the Tropic of Cancer
(B) Day and night are of equal length
(C) The Earth is closest to the Sun
(D) The longest day of the year occurs

(B) Day and night are of equal length
Explanation: During an equinox, the Sun is positioned directly above the Earth’s equator, resulting in nearly equal lengths of day and night across the globe. Equinoxes occur twice a year, around March 21st (Vernal Equinox) and September 23rd (Autumnal Equinox).

51. What is the significance of the summer solstice?

(A) It is the day with the shortest daylight hours of the year
(B) It marks the beginning of autumn
(C) It is the day with the longest daylight hours of the year
(D) It is the day when the Sun is closest to Earth

(C) It is the day with the longest daylight hours of the year
Explanation: The summer solstice is significant because it is the day of the year with the longest period of daylight and the shortest night. It marks the beginning of summer in the Northern Hemisphere and occurs around June 21.

52. The temperature of the Earth’s core is comparable to the temperature of

(A) Sun’s core
(B) Moon’s core
(C) Sun’s surface
(D) Earth’s surface

(C) Sun’s surface
Explanation: The temperature at Earth’s core is estimated to be around 5,400°C (9,800°F), which is roughly as hot as the surface of the Sun. This extreme heat is due to the decay of radioactive elements and residual heat from Earth’s formation.

53. Which layer of the Earth’s atmosphere is the coldest?

(A) Troposphere
(B) Mesosphere
(C) Stratosphere
(D) Thermosphere

(B) Mesosphere
Explanation: The mesosphere is the coldest layer of Earth’s atmosphere, with temperatures dropping as low as -90°C (-130°F) at its upper boundary.

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The Earth Facts | 50+ Important MCQ On The Blue Planet

41. In which layer of Earth’s atmosphere do auroras occur?

42. Which layer of Earth’s atmosphere is most important for radio communication?

43. Which of the following is the most abundant greenhouse gas in Earth’s atmosphere?

44. Which layer of the atmosphere protects Earth from meteoroids?

45. In which layer of Earth’s atmosphere do commercial jets typically fly?

46. What is the gravitational force at the centre of the Earth?

47. Where the gravitational acceleration of the Earth is maximum?

48. What is the primary cause of Earth’s magnetic field?

49. What is the position of the Sun during an equinox?

50. What occurs during an equinox?

51. What is the significance of the summer solstice?

52. The temperature of the Earth’s core is comparable to the temperature of

53. Which layer of the Earth’s atmosphere is the coldest?

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