RBSE Solutions for Class 11 Physical Geography Chapter 4 Interior of the Earth

Rajasthan Board RBSE Class 11 Physical Geography Chapter 4 Interior of the Earth

RBSE Class 11 Physical Geography Chapter 4 Text Book Questions

RBSE Class 11 Physical Geography Chapter 4 Multiple Choice Questions

Question 1.
The constituent elements of the Sial layer are:
(a) Silica – magnesium
(b) Sodium – aluminum
(c) Silica – aluminum
(d) Silica – iron
Answer:
(c) Silica – aluminum

Question 2.
According to Vander Gracht, the maximum depth of the layer above is:
(a) 1,200 km
(b) 60 km
(c) 2,900 km
(d) 200 km
Answer:
(b) 60 km

Question 3.
The statement that is wrong in the perspective of the classification of Suess is:
(a) The density of the upper layer is 2.7
(b) The density of the boundary is lesser than 4.7
(c) Negative properties are found in Nife
(d) Sial is floating on Nife
Answer:
(d) Sial is floating on Nife

Question 4.
Interior of the Earth was divided into the form of Sial, Sima and Nife.
(a) By Van der Gracht
(b) By Dely
(c) By Homes
(d) By Suess
Answer:
(d) By Suess

Question 5.
Which of the following is the direct source of knowledge of interior of the Earth?
(a) Seismic waves
(b) Gravitational force
(c) Volcano
(d) Magnetism of the Earth
Answer:
(c) Volcano

RBSE Class 11 Physical Geography Chapter 4 Very Short Answer Type Questions

Question 1.
Describe the names of the direct sources for the information of earth’s internal structure.
Answer:
The sources from which direct information is received about the internal structure of the Earth are called the direct sources of interior of the Earth’s information. These sources include volcanic eruptions, landslides in the geologic areas and the rock formation on earth’s surface, etc.

Question 2.
What is seismology?
Answer:
An earthquake incident happens in the form of a sudden shaking of the ground. The events that scientists study on the basis of the picture recorded by the seismograph is called seismology. Generally, science studying earthquake is called seismology.

Question 3.
What are the seismic waves?
Answer:
Seismic Waves are waves of energy that travel through the Earth’s layers, and are a result of earthquakes, volcanic eruptions, magma movement, large landslides and large ihan – made explosions that give out low frequency acoustic energy. These waves are of three types.

Question 4.
Why is our information limited about the internal parts of the earth?
Answer:
The interior of the Earth is invisible and unreachable. Dpe to the rapid rise in temperature with depth, more deep mining and exploration are not possible. The instruments also melt at a greater depth due to the high temperature. This is why, our information about the interior of the earth is limited.

Question 5.
What are the main ingredients of Nife?
Answer;
Nife described by Suess is the innermost layer of the Earth, which is formed from nickel and iron metals. That’s why it is called NiFe (Ni + Fe).

RBSE Class 11 Physical Geography Chapter 4 Short Answer Type Questions

Question 1.
Describe the names of internal layers of the earth based on the evidence of seismology.
Answer:
Earth is divided into the following layers, on basis of the earthquake event that occurs on the earth’s surface and the recording of seismic waves produced by it.

  1. Crust – This is the topmost layer.
  2. Mantle – This is the intermediate layer.
  3. Core – This is the innermost layer.

Question 2.
Explain the features of ‘Core’.
Answer:
The following are the features of the Core.

  1. This is the innermost layer of earth.
  2. Its depth ranges from 2900 km to 6371 km.
  3. Density in this layer is 11 grams per cubic cm.
  4. S waves cannot reach this layer of earth.
  5. It is the hardest part of the earth that has been composed of solids.
  6. Core is divided into two parts – the outer core and the internal core.
  7. In this layer of earth, nickel and iron metals are present according to suess.

Question 3.
Enumerate the features of ‘Sial’.
Answer:
Sial has the following features:

  1. It is the outermost layer of the earth as described by Suess.
  2. The predominance of silica and aluminum is found in the composition of this layer.
  3. The average density of this layer is 2.9 grams per cubic cm.
  4. The depth of this layer is up to 50 – 300 km.
  5. This layer contains the primacy of the acid content.
  6. This layer provides different depths and reliefs to continents and oceans.
  7. It is considered to be floating above the sima layer.

Question 4.
What is ‘substratum’? Mention its features.
Answer:
Seismic waves originate during an earthquake occurring on the earth’s surface. One of the layer from the internal layers of the Earth, determined on the basis of these seismic waves, is substratum. Characteristics of substratum are:

  1. It is the intermediate layer of earth based on the classification of seismic waves.
  2. This layer reaches down to the depth of 2900 km below the crust.
  3. The upper part of the substratum is called Astheno sphere.
  4. This layer is the main source of lava released during volcanic eruption.
  5. A substratum is formed from concrete rock.
  6. Due to the heat, pressure and density in this layer, the concrete rock is believed to have a change in the state of matter.

Question 5.
Name the layers of the internal structure of the Earth as suggested by Vander Gracht.
Answer:
A scholar named Vander Gracht has described four layers of the earth’s internal structure. These layers are classified as follows:

1. Outer silica crust:
It is the topmost layer of the earth.

2. Inner silicate layer and mantle:
This is the second layer from the top in the internal structure.

3. Layer of mixed metals and silicate:
This is the third layer in the internal structure.

4. Metallic center or metallic nucleus:
According to Vander Gracht, it is the innermost layer of the Earth.

RBSE Class 11 Physical Geography Chapter 4 Essay Type Questions

Question 1.
Explain the opinion of Vander Gracht about the Interior of the Earth.
Answer:
Among the people who have made representations about the interior structure of the Earth, the prominent place is of Vander Gracht. Vander Gracht has described four layers in the interior structure of the earth. The details of these layers are as follows:

  1. Outer silica crust
  2. Inner silicate layer and mantle
  3. Zone of mixed metals and Silicate
  4. Metallic Nucleus

1. Outer silica crust:
The thickness of this layer varies at different locations. The thickness of this layer is 60 kilometers below the continents, 20 kilometers below the Atlantic Ocean and 10 kilometers below the Pacific Ocean. The density of this layer ranges from 2.75 to 3.1. This layer is made of silica, aluminum, potassium and sodium.
RBSE Solutions for Class 11 Physical Geography Chapter 4 Interior of the Earth img-1
2. Inner silicate layer and mantle:
The thickness of this layer is 60 to 1200 kms. The density of this layer ranges from 3.1 to 4.75. This layer is made of silica, magnesium and calcium.

3. Zone of mixed metals and Silicate:
The thickness of this layer ranges from 1200 to 2900 kms. The density of this layer ranges from 4.75 to 7.8. This layer is made from the mixture of nickel, iron, silica, magnesium, etc.

4. Metalic Nucleus:
This layer extends from 2900 km to the center of earth. The density of this layer is greater than 11. This layer is made of nickel and iron.

Question 2.
Explain the model of Suess in relation to the internal structure of the Earth.
Answer:
According to the classification of the inner structure of the earth by suess, the upper part of the crust is made up of Earth’s sedimanentary rocks. Under this part, Suess has divided the crust internal state of the earth mainly on the basis of the chemical composition.

1. Sial:
According to Suess, it is the uppermost layer of the Earth in which the substances called silica and aluminum are obtained. Therefore this layer is called Sial (Si + al = Sial). The average density of this layer is 2.9 grams per cubic cm. The average depth of this layer is 50 – 300 km. In this layer, the acid content is prominent. It contains rocky stones, basaltic rocks, granite rocks, etc.
RBSE Solutions for Class 11 Physical Geography Chapter 4 Interior of the Earth img-2
2. Sima:
According to Suess, it is the intermediate layer of the Earth, which has the dominance of silica and magnesium. Therefore this layer is called the sima (Si + ma = Sima). The density of this layer is 2.9 – 4.7 grams per cubic cm. The depth of this layer is found to be 1000 – 2000 km. Its composition is from Basalt and Gebro rocks. It has a dominance of alkaline nature in it. Lava comes out of this layer during volcanic eruption.

3. Nife:
According to Suess, it is the innermost layer of the Earth. Nickel and ferrum are present in its formation, so this layer is called (Ni + fe = Nife). The density of this layer is 11 grams per cubic cm. This layer extends from the deepest end of the sima to the earth’s centre. This is the densest layer. The properties of magnetic power exist in it. This classification of Earth presented by Suess is depicted in Fig. 4.2.

Question 3.
Explain the interior structure of the earth based on the evidence of seismology.
Answer:
Seismology is the science in which earthquake waves are studied by marking the seismograph. The nature of these waves, their paths and directions are different. The variations in transmission and speed of these waves can be considered as the basis for knowing the internal structure of the Earth. On this basis, the internal structure of the earth is divided into the following parts:

1. The crust:
It is the topmost layer of the earth. Its average thickness is 30 km. This layer is made of heavy rocks and its density is 3 grams per cubic cm. The thickness of this crust is approximately 30 km on the continents. Under the mountainous parts, it has more depth. It is divided into two parts – 1. Internal crust 2. External crust. In this layer of earth, the prominence of a rock called granite is found. P and S waves are transmitted in this layer, which proves that this layer is made of rocks.

2. The mantle or substratum:
This layer extends to a depth of 2,900 km below the crust. The upper part of the mantle is known as the Astheno Sphere. This part is the main source of lava that reaches the surface of the volcano during its eruption. S waves vanish after the depth of 2,900 km, that is, it is made from unrecognized concrete tiles. In this layer, the waves called P and S have been observed by Gonrad Sir. This layer gives the primacy of basalt rocks. The part between crust and mantle is called Moho – discontinuity,
RBSE Solutions for Class 11 Physical Geography Chapter 4 Interior of the Earth img-3
3. The Core:
The deepest part of the earth from 2900 km to 6371 km. is the most innermost part of the Earth whose average density is 11 grams per cubic cm. In this part, S waves cannot reach. In this layer, there are two parts – 1. External Core 2. Internal Core. The first part is in the liquid state, which extends from 2900 km to the depth of 5150 km. The boundary between the inelastic mantle and the core is called the Gutenberg discontinuity zone.

The inner core is a dense part which extends from 5150 km to 6371 km. The highest density in this part of the earth is 11 grams per cubic cm. It is made of highly rigid metallic content. These layers classified on the basis of earthquake science are depicted through the following diagrams.
RBSE Solutions for Class 11 Physical Geography Chapter 4 Interior of the Earth img-4

RBSE Class 11 Physical Geography Chapter 4 Other Important Questions

RBSE Class 11 Physical Geography Chapter 4 Multiple Choice Questions

Question 1.
The rate of temperature rise from the surface of the earth to its center:
(a) 16 Celsius at 20 meters
(b) 1° Celsius at 32 meters
(c) 2° Celsius at 45 meters
(d) 2° Celsius at 56 meters
Answer:
(b) 1° Celsius at 32 meters

Question 2.
What is the average density of the entire earth?
(a) 2.9 grams per cubic cm
(b) 3.7 grams per cubic cm
(c) 5.5 grams per cubic cm
(d) 11 grams per cubic cm
Answer:
(c) 5.5 grams per cubic cm

Question 3.
The seismology is:
(a) Science studying volcano
(b) Science studying landslide
(c) Science studying earthquake
(d) Science studying flood
Answer:
(c) Science studying earthquake

Question 4.
Which are the most devastating waves?
(a) P waves
(b) S waves
(c) L waves
(d) P* and S* waves both
Answer:
(c) L waves

Question 5.
Which of the following seismic waves brings constriction and expansion in the rocks?
(a) P waves
(b) S waves
(c) Surface waves
(d) None of the above
Answer:
(a) P waves

Question 6.
Which of the following describes the lithosphere?
(a) Upper and Lower Mantle
(b) Crust
(c) Crust and Upper Mantle
(d) Mantle and Crust
Answer:
(c) Crust and Upper Mantle

Question 7.
In which layer Astheno sphere is found?
(a) in Crust
(b) in Mantle
(c) in Core
(d) None of these
Answer:
(b) in Mantle

Matching Type Questions

Question 1.
Match column A to column B in the following:

Column A (Names) Column B (Values)
(i) Temperature (a) Pass through solid, liquid and gas, all three types of substances
(ii) Volcano (b) Vanishing in liquid part
(iii) Primary wave (c) Natural sources
(iv) Secondary wave (d) Ground level
(v) Surface wave (e) Artificial source

Answers:

  1. (e)
  2. (c)
  3. (a)
  4. (b)
  5. (d)

Question 2.
Match column A to column B in the following:

Column A (Name of layer) Column B (Position of layer)
(i) The Crust (a) According to Suess, the Earth’s middle layer
(ii) The Mantle (b) According to Van der Gracht, most internal layer
(iii) The Core (c) According to Suess, the Earth’s innermost layer
(iv) Nife (d) Intermediate layer of the Earth
(v) Sima (e) Earth’s innermost part
(vi) Mixed metallic mass (f) The uppermost layer of the Earth

Answers:

  1. (f)
  2. (d)
  3. (e)
  4. (c)
  5. (a)
  6. (b)

RBSE Class 11 Physical Geography Chapter 4 Very Short Answer Type Questions

Question 1.
What is Lava?
Answer:
During a volcanic eruption, the liquid and semi – solid matter that comes out from the earth’s mantle and reaches to the surface is called lava.

Question 2.
What does Magma mean?
Answer:
‘The substance found in liquid and molten form beneath the surface is called the magma.

Question 3.
What are the artificial sources of information in geology?
Answer:
Temperature, pressure and density are the artificial sources of information in geology.

Question 4.
How much temperature is found at the center of the earth?
Answer:
The temperature at the center of the Earth is more than 2,000°C.

Question 5.
What is the reason for the density increase in the Earth’s layers?
Answer:
Due to continually increasing pressure towards the center of the Earth and due to presence of heavy substances, the density of earth’s layers also increases.

Question 6.
What is the evidence of the state of the liquid at the center of the earth?
Answer:
Through the volcanic eruptions and fluid magma and lava, it is clear that there is a liquid state inside the Earth.

Question 7.
What is earthquake?
Answer:
An earthquake is a sudden vibration of the crust that is produced under the earth’s surface.

Question 8.
What is Focus?
Answer:
The location where the Earthquake begins. The ground ruptures at this spot, then seismic waves radiate out word in all directions.

Question 9.
Write names of seismic waves.
Answer:
Waves generated during earthquake include primary waves (P wave), secondary waves (S wave) and surface waves (L wave).

Question 10.
What are the characteristics of primary waves?
Answer:
Primary waves run at the fastest speed, and these waves can pass through solid, liquid and gas, all three types of substances.

Question 11.
What is the feature of surface waves?
Answer:
Surface waves are the last to travel across the ground from the epicenter. These waves are the most destructive.

Question 12.
What does the Earthquake Shadow Zone mean?
Answer:
The Earthquake Shadow Zone is a region between 105° and 145° to earthquake’s seismic focus where no seismic wave is recorded.

Question 13.
Which device is used to record seismic waves?
Answer:
Seismograph is used to record seismic waves.

Question 14.
What does Astheno sphere mean?
Answer:
The uppermost part of the intermediate layer of the earth (mantle) is called the Astheno sphere.

Question 15.
Into how many parts is the core divided?
Answer:
The core is divided into two parts:

  1. External core.
  2. Internal core.

Question 16.
What is Moho discontinuity ?
Answer:
The incompatibility that occurs between the lower surface of the crust and the upper surface of the mantle is called Moho discontinuity.

Question 17.
According to Vander Gracht, what is the composition of the crust?
Answer:
According to Vander Gracht, the crust is composed of silica, aluminum, potassium and sodium.

Question 18.
What is the depth of the third layer of the earth according to Vander Gracht?
Answer:
According to Vander Gracht, the depth of the third layer of the earth, that is, the mixed metals and silicate layer is from 1200 to 2900 km.

Question 19.
What is the depth of the metallic part (according to Vander Gracht) layer?
Answer:
The depth of the metallic part layer ranges from 2900 km to the earth’s center.

RBSE Class 11 Physical Geography Chapter 4 Short Answer Type Questions (SA-I)

Question 1.
Why is the study of the interior structure of the earth necessary in geography?
Answer:
The earth’s interior structure has a direct impact on the earth’s surface. The study of internal structure of the earth is necessary in geography because the various topographies found on Earth’s surface are the result of geological processes. Occurring inside the earth.

Exogenous processes occurring in the exterior parts of the Earth and endogenous processes occurring in the interior parts bring changes on the Earth’s surface. The terrestrial form is the result of these transformational forces. Human activity and order of life are linked to these forces and landscapes. That is why, studying the interior structure of the Earth is essential.

Question 2.
Describe the sources that provide information about the interior structure of the Earth.
Answer:
Information that we get about the internal structure of the Earth, has two main types of sources:

1. Direct Sources:
Sources from which direct information about the interior structure of the Earth is obtained are called the direct sources. Such as: earth’s rock formation, substances obtained from volcanic eruptions, substances obtained from mining, etc.

2. Indirect Sources:
Sources in which information about the interior structure of the Earth is obtained indirectly are called the indirect sources. Such as: temperature, pressure, density, meteorite, gravity, seismic waves and magnetic fields, etc.

Question 3.
Explain the variations of temperature in the context of Earth’s interior.
Answer:
The rate of temperature rise from the surface of the earth to the center is 1° Celsius per 32 meters. Due to the increase in temperature, all the substances under the earth?s interior should be in the molten state, but in fact, this does not happen. Due to increasing pressure with depth, the melting point of the rocks, and the rate of rise in the temperature decreases towards the center of the earth from a certain point beneath the surface. According to this calculation, the temperature in the center of the Earth is more than 2000°C.

Question 4.
What are seismic waves? Describe their types.
Answer:
Because of the process of energy depletion from the inner part of the Earth, waves that spread outwards from the seismic focus of the earthquake are called seismic waves. They are mainly divided into:

1. Body waves:
Such waves that arise due to the release of energy from the source center of the earthquake and through the inner part of the Earth, move forward in all directions, are called body waves.

2. Surface waves:
New waves caused by interaction between body waves and surface matter are called the surface waves.

Question 5.
Explain the difference between Seismic Focus and Epicenter.
Answer:
Seismic Focus:
In the inner part of the Earth from where the earthquake originates or the place from where the energy begins to be emitted, is called the Seismic Focus. From this place the energy reaches the Earth’s surface, moving in different directions in the form of waves.

Epicenter:
Located above of the seismic focus (at 90° angle), on the earth’s the first place where earthquake waves reach is called the epicenter. It is located at the closest distance from the seismic focus.

Question 6.
What are the Body waves? Give a brief description.
Answer:
Body waves are of two types. They are called ‘P’ waves and ‘S’ waves.

1. ‘P’ waves:
These are also known as primary waves. These are fast moving waves. These waves are like sound waves and reach the surface first. These waves can pass through solid, liquid and gas, all three types of materials.

2. ‘S’ waves:
These are also known as secondary waves. These waves reach the surface some time after the primary waves. These waves can travel only through solids. Because of this characteristic, scientists have been successful in understanding the structure of Earth’s interior.

Question 7.
Summarize the effects of earthquake in brief.
Answer:
Earthquake is a sudden natural phenomenon. This leads to a great loss of human lives and huge public money. Consequences of destructive earthquakes are as follows:

  1. Vibration on the earth’s surface.
  2. surface distortion.
  3. landslide and pulsation.
  4. avalanches.
  5. surface displacement.
  6. soil melting.
  7. unilateral inclination of the surface.
  8. the huge loss of public money due to the collapse of buildings.
  9. fire.
  10. the destruction of buildings, roads and other construction works.
  11. heavy loss of property and goods.
  12. Tsunami waves in the coastal areas, (in case of under sea earthquakes) Loss of public money etc.

Question 8.
Explain the difference between magma and lava.
Answer:
Difference between magma and lava:

Magma Lava
(i) Magma is the thick liquid rock found below the surface of the earth. (i) Lava is the hot molten material coming out of the volcano, which and solidify when it comes to the surface of the earth.
(ii) This creates a plutonic rock under the surface. (ii) This creates volcanic rocks above the surface.
(iii) From this, under the surface, the lattices of betholith, lacolith, phacolith, cil and dyke sheet are formed. (iii) From this, various types of shapes are formed above the surface; Like – Lava Plateau, Cinder Cones, Lava Shield, Caldera.

Question 9.
What is Crust? Describe its main features.
Answer:
The topmost layer of Earth is called the Crust.
Characteristics:

  1. It is the topmost part of the earth’s surface.
  2. Its thickness is found to vary under the continents and the oceans which is 30 km and 5 – 10 km respectively. According to the height in mountainous areas, its depth varies.
  3. This layer is made of heavy rocks. Its density is 3 grams per cubic centimeter.
  4. Ba-salts terraces of crust are built below the oceans.
  5. It has been divided into two parts – inner crust and outer crust.

Question 10.
Mention the characteristics of Sima.
Answer:
This is the second layer according to the chemical composition of the Earth, as described by with Seuss. It has the following characteristics.

  1. This layer is made from silica and magnesium.
  2. Density of this layer is 2, 9 – 4, 7. grams per cubic cm.
  3. This layer extends to the depth of 1000-2000 km.
  4. It has a dominance of alkaline elements.
  5. The lava emerges from this layer during the eruption of a volcano.

RBSE Class 11 Physical Geography Chapter 4 Short Answer Type Questions (SA-II)

Question 1.
Briefly describe the interior parts of the Earth.
Answer:
The interior parts of the Earth are invisible and unreachable. Man has seen the interior part to some extent in direct form through mining and intrusive actions. Due to the rapid increase in temperature with depth, it is not possible to do more deep mining and exploration. There is so much heat under the surface that any kind of instrument used in mining can melt.

Therefore, the mining work is limited to a lesser depth. Volcanic eruptions are the main source of direct information about earth’s internal structure through the emitted lava and gases. There are many anomalies in the interior of the Earth that make it unique.

Question 2.
All the statistics of the Earth’s internal structure are based on indirect sources. How?
Answer:
Humans have no direct means to know the interior structure of the Earth. Human knowledge about the structure of this part is limited to very little depth. Direct knowledge of the structure of the earth can be found only by oil wells, mines to the depth of only 3 to 4 km in most places. It is very minuscule compared to the depth of the center of the Earth (about 6371 km).

By mining activity, we learn that as the depth of the Earth’s surface increases, the temperature and pressure also increase. According to an estimate, the temperature of the inner part of the Earth is approximately 2000°C. Due to such high temperature, it is completely impossible to obtain direct knowledge of the earth’s internal structure.

Therefore, direct study of the interior structure of the Earth is beyond the human capability. With this reason, for obtaining information about the interior part of the earth, man is dependent on indirect sources, like earthquakes, seismic waves, temperature, pressure, meteorites and gravity.

Question 3.
What is earthquake? How does it originate?
Answer:
The earthquake in ordinary language means:
The vibration of the earth. Because of the sudden movement of the crustal plates, the sequence of shocks occurring at some point in crust or mantle is called earthquake. Earthquake is a natural phenomenon in which waves emerge due to the release of energy, which spreads in all directions causing destruction.

Origin of earthquake:
On the surface, crust is often the source of energy on the edge of fault. The crustal (tectonic) plates move and collides with one another, sometime causing faults at impact sites. When the plates dis – enage, huge amounts of energy are released. The slabs on either side of the fault move in the opposite direction, where the top rocks hold the static with the pressure, and the friction between them keeps them interlocked. In spite of this, due to the tendency of separation, the impact of friction decreases.

As a result, the rock clusters suddenly collapse in opposite directions. As a result, energy waves emerge and become dynamic in all directions. These energy waves reach the surface in different directions, consequently the vibrations begin. Thus, earthquake originates.

RBSE Class 11 Physical Geography Chapter 4 Essay Type Questions

Question 1.
Describe the speed, nature and transmission of seismic waves.
Answer:
Transmission of seismic waves:
Seismic waves are the route taken by the tremor of the earthquake during the its occurrence. These waves are of three types. Primary, secondary and surface waves. Based oh the seams and motion of seismic waves, the information about the inner parts of the Earth is found. These waves move straight in the same density part.

But by marking these waves on the earthquake centers, it came to be known that these waves do not move in a straight direction but reflect the shape of the curved path. It proves that the density of the inner parts gets varied. As a result, their path also turns curved. Since the density towards the internal part increases, these waves (P and S) in the core become concave towards tjie surface.

S waves do not pass through liquid and they become extinct at more than 2900 km depth. It proves that the depth more than 2900 km is in a liquid state, which is broad around the center. With varying density of rocks, there is more difference in the speed of the waves at three places.

This motion of seismic waves and the variations found in them are depicted through the following picture:
RBSE Solutions for Class 11 Physical Geography Chapter 4 Interior of the Earth img-5

RBSE Solutions for Class 11 Geography