Test: Our Earth - Year 1 MCQ

The correct answer is Earth.

Key Points

• From the sun, it is the third planet.
• Life existed only on this planet.
• Around 4.5 billion years ago, the earth was formed.
• Inside the solar system, the earth is a rocky planet.
• Earth moves around the sun due to the large mass of the sun.
• In space, the earth also turns around.
• At different times, a different part of the earth is faced by the sun.
• A large amount of liquid water is found only on the earth.
• Water covers around 74 percent area of the earth.
• From different places, the earth's water came.
• Of all the rocky planets, the earth is the largest.
• As compared to Jupiter, it is very small.

Hence, the Earth is known as a blue planet.

The correct answer is Orbit.

• An orbit is the path of a planet around the sun.

Key Points

• Kepler's Law of Planetary Motion states that planets revolve in an elliptical orbit.
• Kepler’s Laws of Planetary Motion:
  • All planets move around the sun in elliptical orbits, with the sun being at rest at one focus of the orbit.
  • The position vector of the planet with the sun at the origin sweeps out equal area in equal time.
  • The square of the period of revolution of a planet around the sun is directly proportional to the cube of the main distance of the planet from the sun.

Additional Information

• Our galaxy is called the Milky Way (or the Akashganga) and it contains about 300 billion stars and one of these is our sun.
  • Planets and other objects go round the sun and make up the solar system with the sun at the center. 
  • Milky Way Galaxy was formed 5 billion years after the Big Bang.

The time between two successive passages of the mean sun across the meridian at noon is known as mean solar time. It means that solar time is equal to one day. Some additional facts:

• 1 Astronomical Unit = 1.5 × 1011 m. It is used to determine the distance between the earth and the sun. 
• 1 Slug = 14.59 kg. It is a unit of mass in the FPS System. 
• 1 Lunar Month = 27.3 solar days. It is the time between the two consecutive full moons. 

Hence, we conclude that one solar day is of 24 hours.

Key Points

Rotation of the earth:

• The Earth rotates on its own axis and it rotates in the eastward direction and in counter-clockwise in prograde motion.
• The rotation of the earth is the cause of the formation of day and night. 
• The direction of the earth’s rotation from west to east is as viewed from the north pole star Polaris.
• The earth rotates once in 24 hours.
• Since the rotation of the earth in the direction from west to east, the moon, sun, and all other celestial bodies appear to move from east to west.
• This is the reason for which we say the sun rises in the east and sets in the west.

So the direction of the earth’s rotation is considered as from west to east.

The correct answer is 1 hour 45 minutes

There is a time lag of two hours from Gujarat to Assam because of the longitudinal extent of India. Gujarat is situated in the extreme west of India while Assam located in the north-eastern part. The Sun rises almost two hours earlier in Assam than in Gujarat.

Key-Points

• India lying entirely in the Northern hemisphere the mainland extends between latitudes 8°4'N and 37°6'N and longitudes 68°7'E and 97°25'E.
• The Westernmost point of India is 68°7'E, known as Ghuar Mati, Gujarat
• Location of Dwarka, Gujarat, India (N 22° 14' 36.0132", E 68° 58' 7.6908") on the map
• Coordinates of Dibrugarh: 27° 28' 22.2024'' N, 94° 54' 43.0704'' E
• The difference between the two points is almost 26°2'.
• Difference of time, 1° longitudinal difference = 4 mins time lag
• 30° longitudinal difference brings 26*4 = 104 mins difference in time
• 104 mins or 1 hour 44 mins hours time-lag between Gujrat and Assam found.
• So it is clear that 1 hour 45 minutes is the local time difference between Dwarka in Gujarat to Dibrugarh in Assam

Hence, option 1 is the correct answer.

The correct answer is Odisha.

Key Points

• The Tropic of Cancer is an imaginary line north from the Equator at an angle of 23.50 degrees.
• Tropic of Cancer passes through 16 countries, 3 continents, and 6 water bodies.
• It passes through 8 Indian states.
  

Additional Information

Concept:

• The rotation of the earth on its axis causes day and night. 
• Whereas change in season happens due to revolution of the earth and the tilt of the axis of the earth
• Earth is tilted at an angle of 23.5
• If the earth was not tilted at all, all regions would have received the same amount of sunlight all through the year and there would have been no change in seas.
• Because of the tilt of the earth's axis, the amount of sunlight that falls on the earth's surface decreases from the equator towards the poles.
• The sun falls directly at the equator, while the poles are tilted farthest from the sun.

Explanation: 

• The Equator is the central latitude of the earth.
• Sun rays fall directly at the equator throughout the year hence it remains warm throughout the year without much change in the seasons.
  

⇒ The equatorial zone has the least seasonal variation on earth

The correct answer is option 2 i.e. Crust and Upper mantle.

Lithosphere

• The lithosphere, that is the rigid outer part of the earth with thickness varying between 10-200 km.
• It includes the crust and the upper part of the mantle. Hence option 2 is correct.
• The lithosphere is broken into tectonic plates (lithospheric plates), and therefore the movement of these tectonic plates cause large-scale changes within the earth’s geological structure (folding, faulting).
• The source of heat that drives plate tectonics is that the primordial heat leftover from the planet’s formation also because the decay of uranium, thorium, and potassium in Earth’s crust and mantle.

The correct answer is option 2 i.e. Northern and Eastern.

• Any circle drawn around the globe divides the Earth into two equal halves called hemispheres.
• There are generally considered to be four hemispheres: Northern, Southern, Eastern, and Western.
• India's main land extends between latitudes 8°4'N and 37°6'N and longitudes 68°7'E and 97°25'E.
• India is located lattitudinally in the Northern hemisphere, the half of earth that is north of the Equator (0°). 
• India is located longitudinally in the Eastern hemisphere, the half of earth that is east of the Prime Meridian or the Greenwich Line (0°).

The correct answer is Mercury.

• Mercury planet is the closest planet to the Sun.

​Key Points

• Mercury:
  • The smallest planet in our solar system
  • It is nearest to the Sun.
  • It's only slightly larger than Earth's Moon.