Ch 2. The Origin And Evolution Of The Earth

Question 1

Who proposed Nebular Hypothesis and in which year and who revised it in 1796 ?

Answer 1

Proposed by German philosopher Immanuel Kant in the year 1755. Revised by mathematician Laplace in 1796

Question 2

What does Nebular Hypothesis state ?

Answer 2

Kant argued that gaseous clouds – nebulae, which slowly rotate, gradually collapse and flatten due to gravity and eventually form stars and planets

Question 3

Binary Theory / Planetesimal Hypothesis was given by ____ and ____ in the year ____

Answer 3

By Chamberlain and Moulton in 1900

Question 4

What is Planetesimal Hypothesis / Binary Theory ?

Answer 4

According to this theory, a star collided with the Sun. As a result, a cigar shaped matter separated from the Sun. After the star moved away, the separated material gradually formed into planets.

Question 5

Who gave the Revised Nebular Hypothesis and in which year ?

Answer 5

By Otto Schmidt of Russia and Carl Weizascar of Germany in 1950

Question 6

What is Revised Nebular Hypothesis ?

Answer 6

The friction and collision of Hydrogen and Helium particles around the Sun helped in the creation of a disc shaped cloud and the planets formed by the process of accretion

Question 7

Who proved Universal expansion and in which year ?

Answer 7

Proved by Sir Edwin Hubble in 1920

Question 8

What is the Big Bang Theory / Expanding Universe Theory ?

Answer 8

A violent explosion of Singularity took place over 13.8 billion years ago from which the universe is formed and is still expanding

Question 9

What is Steady State Theory ?

Answer 9

It asserts that new matter continually should be made to keep a constant density in the Universe

Question 10

What is Cosmic Microwave Background (CMB) ?

Answer 10

The leftover electromagnetic radiation from the Big Bang, or the time when the universe began

Question 11

What is a light year ?

Answer 11

The distance covered by light in one year (speed of light is 3 lakh Km/sec)
1 light year = 9.46 ×10^12 km

Question 12

What is the average diameter of the stars ?

Answer 12

80,000 - 1,50,000 light years

Question 13

What is a Cosmic year / Galactic year ?

Answer 13

250 million years

A cosmic year is the time needed for the solar system to revolve once around the centre of the Milky Way Galaxy.

Question 14

When did the stars form in the Universe ?

Answer 14

Around 5-6 billion years ago

Question 15

What is a Planetesimal ?

Answer 15

A minute planet; a body which could come together with many others under gravitation to form a planet.

Question 16

Nebula of our solar system started to collapse about ____ billion years ago

Answer 16

5-5.6 billion years ago

Question 17

Who gave the dumb-bell shape theory of the Moon formation ?

Answer 17

Sir George Darwin in 1838

Question 18

What is Giant Impact hypothesis / Big splat hypothesis ?

Answer 18

An enormous body which is one to thrice the size of Mars slammed into the Earth not long after its development and shot a huge bit of the Earth into space which later became the Moon

Question 19

When was Moon formed ?

Answer 19

4.4 billion years ago

Question 20

What is Degassing ?

Answer 20

Ejection of gases from the inside of the Earth

Question 21

When was Hydrosphere on Earth formed ?

Answer 21

4000 million (4 billion) years ago

Question 22

Life on Earth started as unicellular creatures ____ million years ago

Answer 22

3800 million (3.8 billion) years ago

Question 23

Name different layers present inside the Earth

Answer 23

Crust, Mantle, Outer core and Inner core

Question 24

When was Photosynthesis evolved on Earth

Answer 24

About 2500 - 3000 million (2.5 - 3 billion) years ago

Question 25

Oxygen content increased in the atmosphere ____ million years ago

Answer 25

2000 million (2 billion) years ago