1.Earth's Internal Structure

Question 1

What are the three layers of the Earth’s interior structure, according to old views?

Answer 1

SiAl, SiMa, NiFe.

Question 2

What is the composition and position of the SiAl layer in the Earth’s interior structure?

Answer 2

Composed of Silica and Aluminium, topmost layer of the Earth, low density, floats on the Sima layer.

Question 3

What is the composition and position of the SiMa layer in the Earth’s interior structure?

Answer 3

Composed of Silica and Magnesium, has higher density.

Question 4

What is the composition and position of the NiFe layer in the Earth’s interior structure?

Answer 4

Composed of Nickel and Iron, innermost layer of the Earth.

Question 5

According to recent views, how is the structure of the Earth similar to that of an onion?

Answer 5

The Earth is divided into Crust, Mantle, and Core.

Question 6

What is the Crust of the Earth, and how much does it contribute to the Earth’s volume and mass?

Answer 6

The Crust contributes around 0.5-1% to the Earth’s volume, and less than 1% of Earth’s mass.

Question 7

What is the average density of the Crust, and how does the temperature change while going inside the Earth’s crust?

Answer 7

The average density of the Crust is 2.7 g/cm3, and the temperature here increases at a very fast rate while going inside the Earth’s crust (for every km, temperature increases by 30° C).

Question 8

How is the Crust divided, and what are its characteristics?

Answer 8

The Crust is divided into Continental Crust and Oceanic Crust. It is very solid and brittle.

Question 9

What is the average depth of the Continental Crust, and how deep can it be in some places like the Himalayas?

Answer 9

The average depth of the Continental Crust is 35 km. It can be up to 100 km in some places like the Himalayas.

Question 10

What are the rocks that the Continental Crust is composed of, and how do they compare to the rocks in the Oceanic Crust in terms of density and weight?

Answer 10

The Continental Crust is composed of granite rocks, which are lighter and less dense. In contrast, the Oceanic Crust is composed of basaltic rocks, which are denser and heavier.

Question 11

What are the most abundant minerals found in the Earth’s crust, and what is the trick to remember their sequence of abundance?

Answer 11

The most abundant minerals found in the Earth’s crust are Oxygen, Silica, Aluminium, Iron, Calcium, Sodium, Potassium, and Magnesium. The trick to remember their sequence of abundance is OSAIC.

Question 12

What is the most abundant mineral found in the entire Earth, and what are the other minerals that follow in abundance after it?

Answer 12

The most abundant mineral found in the entire Earth is Iron, followed by Oxygen, Silicon, and Magnesium.

Question 13

What is the lithosphere and where is it located?

Answer 13

The lithosphere includes the brittle upper portion of the mantle and the crust and is the outermost layer of Earth’s structure. It floats over the Asthenosphere, which is located below it.

Question 14

What is the Asthenosphere and what is its role in volcanic eruptions?

Answer 14

The Asthenosphere is a semi-solid layer located below the lithosphere. It is the house of the ‘Magma chamber’ of the earth that aids in volcanic eruptions.

Question 15

What are the important facts about the Mantle?

Answer 15

The Mantle contributes 83% to Earth’s volume and approx. 67% to its total mass. 45% Oxygen is found here, along with 23% Magnesium and 21% Silicon.

Question 16

What is the Core divided into and what is the Outer Core made of?

Answer 16

The Core is divided into the Outer Core and the Inner Core. The Outer Core is in a liquid state and is made of Nickel, Sulphur, and Iron.

Question 17

What is the lithosphere?

Answer 17

The brittle upper portion of the mantle and the crust, which is the outermost layer of Earth’s structure.

Question 18

What is the Asthenosphere?

Answer 18

The layer below the lithosphere, which is semi-solid in nature and has a greater density than the lithosphere.

Question 19

What is the Magma chamber?

Answer 19

It is the house of the ‘Magma chamber’ of the earth that aids in a volcanic eruption, found in the Asthenosphere.

Question 20

What is the zone of low velocity in the mantle?

Answer 20

The Asthenosphere is the zone of low velocity, where the speed of Primary waves and Secondary Waves reduces.

Question 21

What is the contribution of the Mantle to Earth’s volume and total mass?

Answer 21

The Mantle contributes 83% to Earth’s volume and approx. 67% to the total mass of the Earth.

Question 22

What are the major elements found in the Mantle?

Answer 22

Oxygen (45%), Magnesium (23%) and Silicon (21%) are the major elements found in the Mantle.

Question 23

What is Magma and Lava?

Answer 23

Magma refers to molten rocks inside the Earth, whereas Lava refers to molten Lava outside the Earth.

Question 24

What is the Outer Core made of?

Answer 24

The Outer Core is made of Nickel, Sulphur and Iron.

Question 25

What is the contribution of the Core to Earth’s volume and total mass?

Answer 25

The Core contributes 16% to Earth’s volume and approx. 33% to the total mass of the Earth.

Question 26

Why is the Outer Core in a liquid state?

Answer 26

The Outer Core is in a liquid state due to the presence of radioactive elements leading to nuclear fusion and primordial heat.

Question 27

What causes the magnetic field of the Earth to evolve?

Answer 27

Convective currents in the outer core.

Question 28

Why does the liquid at great depths become lighter?

Answer 28

Due to excessive temperature, the liquid expands.

Question 29

What happens to the liquid when it reaches the boundary of the core and mantle?

Answer 29

The liquid rises and expands due to the higher temperature at the base of the outer core and the lower pressure at the boundary.

Question 30

What was the initial temperature of the Earth?

Answer 30

8000° C.

Question 31

When did the formation of the Earth’s crust take place?

Answer 31

3.5 billion years ago.

Question 32

What is the first relief feature of the Earth?

Answer 32

The crust.

Question 33

What happened when the crust acted like a thin lid for the release of heat trapped inside the Earth?

Answer 33

Volcanic eruptions occurred, leading to irregularities in the Earth’s crust.

Question 34

What is the period between 3.5 billion to 2.5 billion years ago referred to as?

Answer 34

The Great Tecto Volcanic Age.

Question 35

What is the temperature of the inner core?

Answer 35

About 6000°C.

Question 36

Where is the maximum density of the Earth’s surface found?

Answer 36

In the inner core, at 13 g/cm3.