Maharashtra Board Class 8 Geography Chapter 2 Interior of the Earth Solutions

Class 8 Geography Chapter 2 Interior Of The Earth Questions And Answers Maharashtra Board

Interior Of The Earth Class 8 Questions And Answers Chapter 2 Maharashtra Board

Class 8 Geography Chapter 2 Interior Of The Earth Textbook Questions And Answers

 

Question A.There are two layers in the crust.
(a) Inner and outer crust []
(b) Continental and oceanic crust [ ]
(c) Surface and oceanic crust []
(d) Mantle and core []
Answer: (b) Continental and oceanic crust
In simple words: The Earth's outermost layer, the crust, is fundamentally divided into two distinct types: the continental crust, which forms the landmasses, and the oceanic crust, found beneath the oceans.

🎯 Exam Tip: Remember the primary classification of the Earth's crust into continental and oceanic types, as this is a fundamental concept in geology.

 

Question B.Which element is found in both mantle and crust?
(a) Silica []
(b) Magnesium []
(c) Aluminium []
(d) Iron []
Answer: (b) Magnesium
In simple words: Magnesium is an element commonly found in both the crust, which is the Earth's surface layer, and the mantle, the thick layer beneath the crust.

🎯 Exam Tip: Identifying common elements across Earth's layers helps understand their geological composition and interconnections. Magnesium's presence in both crust and mantle is a key detail.

 

Question C.Which of these minerals are found in the core of the earth?
(a) Iron - magnesium []
(b) Magnesium – nickel [ ]
(c) Aluminium – iron [ ]
(d) Iron - nickel []
Answer: (d) Iron - nickel
In simple words: The Earth's core is primarily composed of heavy metals, with iron and nickel being the most abundant elements found there.

🎯 Exam Tip: The composition of the Earth's core, predominantly iron and nickel, is crucial for understanding its density, magnetic field generation, and overall structure.

 

Question D.The inner core is in which state?
(a) Gaseous []
(b) Solid []
(c) Liquid []
(d) Semi-solid []
Answer: (a) Gaseous
In simple words: Despite immense pressure, the extreme temperatures at the Earth's inner core are so high that scientists believe its iron and nickel exist in a super-heated gaseous state.

🎯 Exam Tip: Understanding the state of matter (solid, liquid, gaseous) for each layer, especially the extreme conditions of the inner core, is important for questions on Earth's internal structure.

 

Question E.The outer core is made up of
(a) Iron []
(b) Gold []
(c) Hydrogen []
(d) Oxygen []
Answer: (a) Iron
In simple words: The outer core of the Earth is mainly composed of molten iron, along with some nickel and other lighter elements.

🎯 Exam Tip: Differentiate between the compositions of the inner and outer core, specifically noting the liquid nature of the outer core and its primary component, iron.

 

Question F.The layer of the earth on which we live...
(a) Mantle []
(b) Core []
(c) Crust []
(d) Continental crust [ ]
Answer: (d) Continental crust
In simple words: We primarily live on the continental crust, which is the thicker, less dense part of the Earth's outermost layer forming the landmasses.

🎯 Exam Tip: Be precise when answering questions about where we live; while 'crust' is generally correct, 'continental crust' is more specific and accurate for land-based habitats.

 

2. Tell Whether Right Or Wrong. Correct The Wrong Statement

 

Question A.The density of various materials is not the same in the interior of the earth.
Answer: Correct.
In simple words: The Earth's interior is not uniformly dense; materials become progressively denser as you go deeper towards the core.

🎯 Exam Tip: The concept of increasing density with depth is a key indicator of Earth's layered structure and composition.

 

Question B.The core of the earth's interior is made up of hard rocks.
Answer: Incorrect.
Correct statement: The core of the earth's interior is made up of elements, viz. iron and nickel.
In simple words: The Earth's core is primarily composed of molten and solid metals like iron and nickel, not hard rocks.

🎯 Exam Tip: It's important to distinguish between the rocky composition of the crust and mantle and the metallic composition of the core to avoid common misconceptions.

 

Question C.Secondary waves cannot pass through outer core.
Answer: Correct.
In simple words: Secondary (S) earthquake waves cannot travel through liquids, and since the Earth's outer core is liquid, these waves are unable to pass through it.

🎯 Exam Tip: The behavior of seismic waves, particularly S-waves, is critical evidence for inferring the liquid state of the Earth's outer core.

 

Question D.Continental crust is made up of silica and magnesium.
Answer: Incorrect.
Correct statement: Continental crust is made up of silica and aluminum.
In simple words: The continental crust is primarily composed of silica and aluminum, not magnesium, which is more prevalent in the oceanic crust.

🎯 Exam Tip: Differentiating the main elemental compositions of continental (Sial - Silica + Aluminum) and oceanic crust (Sima - Silica + Magnesium) is essential for accuracy.

 

3. Answer The Following

 

Question A.What are the two parts of the crust? What is the basis of classification?
Answer:
1. Continental crust and the Oceanic crust are the two parts of the crust.
2. The crust is classified on the basis of whether it lies below the land or the ocean.
3. The part of the crust lying below the continent is known as the continental crust.
4. The part of the crust lying below the ocean is known as the oceanic crust.
In simple words: The Earth's crust is divided into continental and oceanic parts, classified based on whether they form landmasses or lie beneath the oceans, respectively.

🎯 Exam Tip: When describing the crustal divisions, clearly state both parts and explicitly mention the geographical location (land/ocean) as the classification basis.

 

Question B.Why is the upper layer of the mantle known as the asthenosphere?
Answer:
1. The upper layer of the mantle is in liquid state.
2. The rocks in the upper 100 to 200 km of the mantle melt due to the heat and magma is created. Magma chambers are found in this layer of the earth.
3. Due to the heat and pressure, the energy waves are created in mantle. These energy waves move in vertical direction and magma comes out on the surface of the earth by volcanic eruptions.
4. These endogenitic movements continuously occur in the upper layer of the mantle. Therefore, the upper layer of the mantle is known as the asthenosphere.
In simple words: The upper mantle is called the asthenosphere because its rocks are semi-molten due to intense heat and pressure, allowing for plastic flow and driving tectonic plate movements.

🎯 Exam Tip: Emphasize the semi-molten (plastic) nature and the resulting internal movements when explaining why the upper mantle is called the asthenosphere, linking it to magma formation and volcanic activity.

 

Question C.Magnetosphere of the earth is a result of rotation. Explain.
Answer:
1. The average temperature of the outer core of the earth is around 5000° C. The average temperature of the inner core of the earth is around 6000° C. This difference between the temperature results in formation of vertical currents.
2. The rotation of the earth gives eddy (circular) motion to these currents.
3. Electric currents develop in these spiral eddies of liquid iron leading to generation of the magnetic field of the earth. This magnetic field is called magnetosphere. In this way, the magnetosphere is formed due to the rotation of the earth.
In simple words: Earth's rotation causes the molten iron in its outer core to move in swirling currents, generating electric currents that produce the Earth's magnetic field, also known as the magnetosphere.

🎯 Exam Tip: Connect the Earth's rotation directly to the convection currents in the liquid outer core and the subsequent generation of electric currents to explain the formation of the magnetosphere.

 

4 Draw Neat Diagrams. Label Them And Explain.

 

Question A.The interior of the earth
Answer:
ℹ️ चित्र व्याख्या (Diagram Explanation): पृथ्वी के आंतरिक भाग का एक आरेखीय चित्रण जो विभिन्न परतों जैसे क्रस्ट, मेंटल, और कोर (बाहरी और आंतरिक) को दर्शाता है। यह पृथ्वी की संरचना और उनकी औसत मोटाई को समझाता है, साथ ही लिथोस्फीयर की अवधारणा को भी स्पष्ट करता है।
Explanation:
1. Inner Core: It is the center and the hottest layer of the Earth. The inner core is solid and made up of iron and nickel.
2. Outer Core: The outer core of the Earth is similar to a very hot ball of metals. It is composed of metals such as iron and nickel. The outer core surrounds the inner core.
3. Mantle: Mantle is the widest section of the Earth. Mantle is mainly made up of semi-molten rock known as magma. The rock is hard in the upper part of the mantle, but lower down the rock is softer and begins to melt. The mantle consists of very hot and dense rock.
4. Crust: The crust is the outer layer where we live. It's a solid rock layer divided into two types: Continental crust covers the land and Oceanic crust covers water.
In simple words: The Earth's interior is structured into distinct layers: the solid inner core, the liquid outer core, the semi-molten mantle, and the thin, rocky crust, each with unique compositions and states.

🎯 Exam Tip: For diagram-based questions, ensure your explanation clearly describes each labeled part and its key characteristics, such as state of matter, composition, and relative position.

 

Question B.Magnetic pole and equator
Answer:
ℹ️ चित्र व्याख्या (Diagram Explanation): पृथ्वी के भू-चुंबकीय अक्ष और भौगोलिक अक्ष को दर्शाने वाला एक आरेख। यह चुंबकीय ध्रुवों और भूमध्य रेखा के संबंध को दिखाता है, साथ ही चुंबकीय क्षेत्र की रेखाओं को भी, जो पृथ्वी के आंतरिक भाग में उत्पन्न होती हैं।
In simple words: The Earth's magnetic poles, where magnetic field lines converge, are distinct from the geographical poles and are generated by the planet's rotating molten core.

🎯 Exam Tip: Clearly differentiate between the geographical and geomagnetic poles and equators, and explain how the Earth's internal processes create the magnetic field.

 

5. Give Geographical Reasons:

 

Question A.There are discontinuities in the interior of the earth.
Answer:
1. There is a difference between the elements, temperatures and the pressure found in the three parts of the interior of the earth, viz, crust, mantle and core.
2. In the interiors of the earth, the transitional areas are found between (a) continental crust and oceanic crust (b) crust and mantle (c) upper mantle and lower mantle (d) mantle and core and (e) outer core and inner core. Therefore, there are discontinuities in the interior of the earth.
In simple words: Discontinuities exist within the Earth's interior due to abrupt changes in composition, temperature, and pressure at the boundaries between its distinct layers like the crust, mantle, and core.

🎯 Exam Tip: When explaining discontinuities, highlight the abrupt changes in physical properties and chemical composition that define the boundaries between Earth's major internal layers.

 

Question B.There is correlation between the density of metals and their location in the interior of the earth.
Answer:
1. The rocks found in the crust have predominance of the compounds of silicon, aluminium, magnesium, etc. These compounds are lighter in weight. Therefore, they are found in the upper layer of the interior of the earth.
2. The elements like iron, nickel are found in the core of the earth. These elements are heavier in weight. Thus, metals with low density are found in upper level in the interior of the earth and the metals with high density are found in the lower level in the interior of the earth. Thus, there is correlation between the density of metals and their location in the interior of the earth.
In simple words: Denser materials like iron and nickel sank to the Earth's core during its formation, while lighter elements like silicon and aluminum remained closer to the surface, creating a clear correlation between density and depth.

🎯 Exam Tip: Explain the concept of differentiation (gravitational sorting) during Earth's formation, where denser elements migrated to the core, while lighter ones formed the crust and mantle, linking density to depth.

 

Question C.Mantle is the centre of earthquake and volcanic eruptions.
Answer:
1. The rocks in the upper 100 to 200 km of the mantle melt due to the heat and the magma is created.
2. Magma chambers are found in this layer of the earth.
3. Due to the heat and pressure, the energy waves are created in mantle. These energy waves move in vertical direction and magma comes out on the surface of the earth by volcanic eruptions. Thus, mantle is the centre of earthquake and volcanic eruptions.
In simple words: The mantle is where intense heat and pressure cause rocks to melt, forming magma, and where convection currents create energy waves, driving both volcanic eruptions and the tectonic plate movements that cause earthquakes.

🎯 Exam Tip: Focus on the thermal processes and resulting movements (convection, magma generation) within the mantle, as these are the direct causes of earthquakes and volcanic activity.

 

Question D.The thickness of the crust below the continents is more as compared to oceans.
Answer:
1. The density of the crust below the continents is \(2.65\) to \(2.90 \, \text{gm/cm}^3\). The density of the crust below the oceans is \(2.90\) to \(3.3 \, \text{gm/cm}^3\).
2. As the density of the crust below the continents is comparatively low, it keeps floating on the mantle. It does not subduct into mantle. As its effect, the thickness of the crust below the continents is found to be high.
3. As the density of the crust below the ocean is comparatively high, it subducts into mantle leading to its low thickness. Thus, the thickness of the crust below the continents is more as compared to oceans.
In simple words: Continental crust is thicker because its lower density allows it to float higher on the mantle without subducting, unlike the denser oceanic crust which tends to subduct, making it thinner.

🎯 Exam Tip: Emphasize the role of density difference (continental crust being less dense than oceanic crust) in explaining why continental crust floats higher and is consequently thicker.

 

Question E.Earth is protected because of the magnetosphere.
Answer:
1. The ozone layer protects the earth from ultraviolet radiation.
2. The earth's magnetosphere serves to deflect most of the solar wind, whose charged particles would otherwise strip away the ozone layer. In this way, the earth is protected because of the magnetosphere.
In simple words: The magnetosphere acts as a protective shield, deflecting harmful solar wind particles and preventing them from eroding Earth's atmosphere, including the vital ozone layer.

🎯 Exam Tip: Clearly explain the dual protection mechanism: the magnetosphere deflects solar wind, which in turn protects the ozone layer from being stripped away, highlighting its indirect role in preserving life.

 

Know This Too:

1. The average density of the earth is \(5.5 \, \text{gm/cm}^3\).
2. The rocks in the upper 100 to 200 km of. the mantle melt due to heat.
3. The mixture of molten rocks, volatiles, etc. found beneath the surface of the earth is called magma.
4. The mixture of molten rocks, volatiles, etc. erupted from volcano or fissure on the surface of the earth is called lava.

Activity:

 

Question 1.Prepare a model of the earth's interior.
Answer:
1. The interior of the earth will be very hot.
2. Huge sized rocks will be present I in the upper layers of the interior of the earth.
3. Due to extreme heat and pressure, the rocks must be melting in the interior of the earth.
4. Due to the melting of the rocks, magma will be created in the interior of the earth.
5. Due to endogenous movements in the interior of the earth, volcanic eruptions will occur on the surface of the earth.
6. The primary earthquake waves will be travelling through the mantle and the core of the earth.
7. The secondary earthquake waves will be travelling only through the mantle of the earth.
8. The temperature in the interior of the earth will get increased with the depth.
9. The highest temperature will be found at the centre of the earth.
10. The elements like silica, aluminium, magnesium, iron and nickel will be found in the various layers of the interior of the earth.
In simple words: A model of Earth's interior would show extremely hot, dense layers, with molten magma driving volcanic activity and distinct compositions of elements like iron and nickel at varying depths.

🎯 Exam Tip: For model-based questions, list key characteristics and processes (temperature, composition, state of matter, geological events) that define the Earth's interior for a comprehensive answer.

 

Class 8 Geography Chapter 2 Interior Of The Earth Additional Important Questions And Answers

 

Question A.Which seismic waves can travel through liquid medium?
(a) Primary waves [ ]
(b) Secondary waves [ ]
(c) Surface waves []
(d) Oceanic waves [ ]
Answer: (a) Primary waves
In simple words: Primary waves, also known as P-waves, are compressional waves that can travel through all states of matter, including liquid mediums.

🎯 Exam Tip: Remember that P-waves are the only seismic waves capable of propagating through liquids, a crucial fact used to infer the liquid nature of Earth's outer core.

 

Question B.Which of the following layers of the earth has the highest density?
(a) Crust []
(b) Mantle []
(c) Outer core []
(d) Inner core []
Answer: (d) Inner core
In simple words: The Earth's inner core, composed primarily of solid iron and nickel under immense pressure, is the densest layer of the planet.

🎯 Exam Tip: The inner core's density is the highest due to its composition of heavy elements and the extreme pressure exerted on it by all overlying layers.

 

Question C.Which of the following waves can travel through all the layers of the interior of the earth?
(a) Primary []
(b) Secondary []
(c) Tertiary []
(d) Surface []
Answer: (a) Primary
In simple words: Primary (P) seismic waves are unique in their ability to travel through all layers of the Earth's interior, whether solid or liquid.

🎯 Exam Tip: This question tests knowledge of seismic wave properties. P-waves' ability to pass through all mediums is fundamental to seismology.

 

Question D.Which of the following layers of the interior of the earth is in solid form and cool?
(a) Crust []
(b) Mantle []
(C) Outer core []
(d) Inner core []
Answer: (a) Crust
In simple words: The crust is the outermost layer of the Earth, which is predominantly solid and the coolest among the major interior layers.

🎯 Exam Tip: While "cool" is relative, the crust is the coolest and most solid outer layer compared to the much hotter and sometimes molten layers beneath it.

 

Examine The Statements And Incorrect Ones :

 

Question A.As we move deeper the surface, temperature keeps decreasing.
Answer: Incorrect.
Correct statement: As we move deeper the surface, temperature keeps increasing.
In simple words: The Earth's interior gets progressively hotter with increasing depth due to residual heat from planetary formation and radioactive decay.

🎯 Exam Tip: This is a common misconception; always remember that temperature significantly increases as one goes deeper into the Earth's interior.

 

Question B.Magma chambers are found in lower mantle.
Answer: Incorrect.
Correct statement: Magma chambers are found in upper mantle.
In simple words: Magma chambers, where molten rock accumulates, are primarily located within the upper mantle, not the lower mantle.

🎯 Exam Tip: Accurately identifying the location of geological features like magma chambers to the correct Earth layer is crucial for understanding volcanic processes.

 

Question C.The discontinuity is found between the crust, mantle and core.
Answer: Correct.
In simple words: Discontinuities, marked by changes in seismic wave velocity, exist at the major boundaries separating the crust, mantle, and core.

🎯 Exam Tip: Recognize that "discontinuities" refer to the transition zones or boundaries between Earth's distinct layers, such as the Mohorovičić discontinuity (crust-mantle) and the Gutenberg discontinuity (mantle-core).

 

Answer The Following Questions In One Sentence Each:

 

Question A.In which of the layers of the interior of the earth is magma formed?
Answer: Magma is formed in the mantle (upper mantle) of the earth.
In simple words: Magma originates in the upper mantle where intense heat causes rocks to melt.

🎯 Exam Tip: Pinpoint the upper mantle as the primary zone for magma generation, distinguishing it from other layers.

 

Question B.What are the two parts of the core?
Answer: Outer core and inner core are the two parts of the core.
In simple words: The Earth's core is divided into an outer liquid layer and an inner solid layer.

🎯 Exam Tip: Always specify both the outer (liquid) and inner (solid) parts when asked about the Earth's core structure.

 

Match The Columns And Complete The Chain :

 

Question A.'A' Column (The layer
of the interior of the
earth)
'B' Column (Density)
'C' Column (Elements found)
1. Sial
(i) \(13.3 \, \text{gm/cm}^3\)
(a) Silica and Magnesium
2. Sima
(ii) \(2.65\) to \(2.90 \, \text{gm/cm}^3\)
(b) Nickel and Iron
3. Inner core
(iii) \(2.90\) to \(3.3 \, \text{gm/cm}^3\)
(c) Silica and Aluminium
Answer:

'A' Column (The layer of the interior of the earth)	'B' Column (Density)	'C' Column (Elements found)
1. Sial	(ii) \(2.65\) to \(2.90 \, \text{gm/cm}^3\)	(c) Silica and Aluminium
2. Sima	(iii) \(2.90\) to \(3.3 \, \text{gm/cm}^3\)	(a) Silica and Magnesium
3. Inner core	(i) \(13.3 \, \text{gm/cm}^3\)	(b) Nickel and Iron

In simple words: This table matches specific Earth layers (Sial, Sima, Inner Core) with their characteristic densities and predominant elemental compositions.

🎯 Exam Tip: For match-the-column questions, carefully cross-reference each item from Column A with its correct corresponding properties in Columns B and C, ensuring accuracy for density and elemental makeup.

 

Answer The Following Questions In Brief:

 

Question A.Describe the changes that take place in the temperatures from the surface of the earth to its centre.
Answer:
1. The process of cooling of the earth started from the surface. The temperature goes on increasing from the surface towards the core.
2. The surface of the earth is cool and solid.
3. The centre of the earth is extremely hot. The temperature at the centre of the earth is around \(5500^\circ\) to \(6000^\circ \, \text{C}\).
In simple words: From the relatively cool surface, the Earth's temperature dramatically increases with depth, reaching extreme highs of \(5500^\circ\) to \(6000^\circ \, \text{C}\) at its scorching center.

🎯 Exam Tip: Clearly articulate the trend of increasing temperature with depth and provide approximate temperature ranges for the Earth's center to demonstrate detailed understanding.

 

Question B.Describe the changes that take place in the density of the earth from its surface to the centre.
Answer:
1. The density of the earth goes on increasing from its surface to the centre.
2. The average density of the crust of the earth is approximately \(2.98 \, \text{gm/cm}^3\).
3. The average density of the mantle of the earth is approximately \(5.7 \, \text{gm/cm}^3\).
4. The average density of the outer core of the earth is approximately \(9.8 \, \text{gm/cm}^3\).
5. The density of the inner core at the centre of the earth is approximately \(13 \, \text{gm/cm}^3\).
In simple words: The Earth's density steadily increases from the lighter crust, through the denser mantle, to the extremely dense metallic inner core, reflecting the gravitational sorting of materials during its formation.

🎯 Exam Tip: Provide specific density values for each major layer (crust, mantle, outer core, inner core) to support the general statement about increasing density with depth.

 

Question C.Write in brief about the travelling of various types of earthquake waves through the layers of interior of the earth.
Answer:
1. The primary earthquake waves travel through the mantle as well as the core of the earth.
2. While travelling through the core of the earth, the direction of the primary earthquake waves gets altered.
3. While travelling through the core, the speed of the primary earthquake waves decreases.
4. The secondary earthquake waves can travel only through the mantle of the earth. These waves get absorbed in the core of the earth. Thus, these waves cannot travel through the core of the earth.
In simple words: Primary (P) waves travel through all layers but change speed and direction in the core, while secondary (S) waves can only pass through the solid mantle, being absorbed by the liquid outer core.

🎯 Exam Tip: Clearly differentiate the behavior of P-waves and S-waves in terms of their ability to pass through solid vs. liquid layers, and mention changes in speed and direction as key characteristics.

 

Write Short Notes On The Following:

 

Question A.The crust.
Answer:
1. The uppermost layer of the interior of the earth is called the crust. Continental crust and the oceanic crust are the two parts of the crust.
2.The thickness of the continental crust is approximately 16 km to 45 km. On the other hand, the thickness of the oceanic crust is approximately 7 km to 10 km
3. The density of the continental crust is approximately \(2.65\) to \(2.90 \, \text{gm/cm}\). On the other hand, the density of the oceanic crust is approximately \(2.65\) to \(2.90 \, \text{gm/cm}^3\).
4. Silica and aluminium are the main elements found in the continental crust. Therefore, it is also called Sial. On the other hand, Silica and Magnesium are the main elements found in the oceanic crust. Therefore, it is also called Sima.
In simple words: The crust is Earth's thin, outermost rocky layer, divided into thicker, less dense continental crust (Sial) and thinner, denser oceanic crust (Sima), each with distinct compositions and thicknesses.

🎯 Exam Tip: In a short note on the crust, ensure you include its definition, two main types (continental and oceanic), their relative thicknesses, densities, and primary elemental compositions (Sial/Sima).

Question B.The outer core.
Answer:1. The outer core is located below the lower mantle. 2. It is located at the depth from 2900 km to 5100 km from the surface of the earth. 3. The average temperature of the outer core of the earth is around 5000° C. The density of the outer core of the earth is approximately 9.8 gm/cm.In simple words: The outer core is a liquid layer of the Earth, found beneath the lower mantle. It's very hot, with an average temperature of about 5000° C, and has a density of roughly 9.8 gm/cm.

🎯 Exam Tip: Remember the depth and temperature ranges for the outer core as they are key descriptive characteristics for this layer.

Question C.The inner core.
Answer:1. The inner core is located below the upper core. 2. It is located at the depth from 5150 km to 6371 km from the surface of the earth. 3. The average temperature of the inner core of the earth is around 6000° C. The density of the inner core of the earth is approximately 13.3 gm/cm³. 4. The elements, viz. Iron (Ferrous) and Nickel (Ni) are mainly found in the inner core of the earth. Therefore, it is also called Nife. 5. The temperature at the centre of the earth is almost equivalent to the surface temperature of the sun.In simple words: The inner core is the Earth's solid, innermost layer, primarily composed of iron and nickel (Nife). It's extremely hot, reaching temperatures comparable to the sun's surface, and extends from about 5150 km to 6371 km depth with a high density of 13.3 gm/cm³.

🎯 Exam Tip: Focus on the composition (Nife), state (solid), and extreme temperature of the inner core, as these are frequently tested facts.

Give Geographical Reasons For The Following:

Question A.The secondary waves of earthquake cannot travel through the core of the earth.
Answer:1. The secondary waves of earthquake can travel only through the solid state of the interior of the earth. 2. The outer core of the centre of the earth is in liquid state. Therefore, the secondary waves of earthquake cannot travel through the core of the earth.In simple words: Secondary (S) earthquake waves can only move through solid materials. Since the Earth's outer core is in a liquid state, S-waves cannot pass through it, providing evidence for the liquid nature of this layer.

🎯 Exam Tip: Understanding the behavior of P-waves and S-waves is crucial for inferring the Earth's internal structure and material states.

Question B.The inner core is called Nife.
Answer:1. The inner core predominantly comprises iron and nickel. 2. The word Nife is derived from the word Nickel (Ni) and Iron (Ferrous) (Fe). Therefore, the inner core is called (Ni + Fe) Nife.In simple words: The inner core is named Nife because it is primarily composed of Nickel (Ni) and Iron (Fe), with 'Ni' representing Nickel and 'Fe' representing Iron.

🎯 Exam Tip: Knowing the elemental composition and the derivation of the name 'Nife' for the inner core is important for geology concepts.

Question C.The upper layer of the crust is called Sial.
Answer:1. The rocks in the upper layer of the crust have predominance of the compounds of silicon and aluminium. 2. The word Sial is derived from the word Silica (Si) and Aluminium (Al). Therefore, the upper layer of the crust is called (Si + Al) Sial.In simple words: The upper crust is called Sial because it's rich in Silicon (Si) and Aluminium (Al), with the name being an acronym formed from these dominant elements.

🎯 Exam Tip: Remember the chemical composition (Silicon and Aluminium) that gives the upper crust its 'Sial' designation.

Question D.The lower layer of the crust is called Sima.
Answer:1. The rocks in the lower layer of the crust have predominance of the compounds of silicon and magnesium. 2. The word Sima is derived from the word Silica (Si) and Magnesium. (Ma). Therefore, the lower layer of the crust is called (Si + Ma) Sima.In simple words: The lower crust is known as Sima because it is primarily made of Silicon (Si) and Magnesium (Ma), with the name being a combination of these two elements.

🎯 Exam Tip: Distinguish between Sial and Sima by remembering their respective dominant elemental compositions (Aluminium vs. Magnesium).

Study The Following Map/ Figure /Graph And Answer The Following Questions:

ℹ️ चित्र व्याख्या (Diagram Explanation): यह आरेख पृथ्वी के आंतरिक भाग में भूकंपीय तरंगों की गति, गहराई और दबाव के संबंध को दर्शाता है। चित्र (A) गहराई के साथ प्राथमिक (Primary) और द्वितीयक (Secondary) तरंगों की गति में बदलाव को दिखाता है, साथ ही क्रस्ट/ऊपरी मेंटल, परिवर्तन क्षेत्र, निचले मेंटल और कोर को भी दर्शाता है। चित्र (B) पृथ्वी की गहराई के साथ घनत्व और गुरुत्वाकर्षण तीव्रता में परिवर्तन को दर्शाता है, जिससे विभिन्न परतों में इन गुणों का वितरण स्पष्ट होता है।

Question A.At what depth does the curve of the secondary waves seem to have ended in figure (A)?
Answer:The curve of the secondary waves seems to have ended around the depth of 2900 km in figure (A).In simple words: In diagram (A), the secondary waves stop propagating at approximately 2900 km depth.

🎯 Exam Tip: Pay close attention to the X and Y axes on graphs to accurately interpret specific data points like wave termination depths.

Question B.What is the velocity of the secondary waves around the boundary of the outer core shown in figure (A)?
Answer:The velocity of the secondary waves is 6 to 8 km/sec around the boundary of the outer core shown in figure (A).In simple words: At the boundary of the outer core in figure (A), the secondary waves show a velocity between 6 and 8 km/sec before they terminate.

🎯 Exam Tip: When reading graphs, estimate ranges carefully when an exact point isn't explicitly labeled, focusing on the trend leading up to the boundary.

Question C.What conclusion can be drawn on the basis of the curve of the secondary waves stopping around the depth of 2900 km?
Answer:On the basis of the curve of the secondary waves stopping around the depth of 2900 km, it can be concluded that secondary waves do not enter the core.In simple words: Since secondary waves cannot travel through liquids, their abrupt stop at around 2900 km depth indicates that the Earth's core, at least its outer part, is liquid.

🎯 Exam Tip: The disappearance of S-waves at the core-mantle boundary is a critical piece of evidence for the Earth's liquid outer core.

Question D.What is the velocity of the primary waves at the time of entering the outer core shown in figure (A)?
Answer:The velocity of the primary waves at the time of entering the outer core shown in figure (A) is 8 km/sec.In simple words: As primary waves enter the outer core in figure (A), their velocity is measured at 8 km/sec.

🎯 Exam Tip: Note the change in P-wave velocity at layer boundaries, as this change reflects differences in material density and state.

Question E.What conclusions can be drawn about the intensity of the gravitational force shown in Figure (B)?
Answer:The following conclusions can be drawn about the intensity of the gravitational force shown in Figure (B): 1. Gravitational force increases at certain depth from the surface of the earth and then it reduces according to the depth. 2. At the centre of the earth, the gravitational force is zero.In simple words: Figure (B) shows that gravitational force initially increases with depth from the Earth's surface, then decreases, eventually becoming zero at the very center of the Earth.

🎯 Exam Tip: Understand that while mass increases with depth, the gravitational force eventually decreases towards the center due to the cancellation of gravitational pulls from surrounding mass, becoming zero at the exact center.

Thought-Provoking Question:

Think About It:

Question 1.Imagine about the earth's interior and- write 10-12 sentences on it.
Answer:1. The interior of the earth will be very hot. 2. Huge sized rocks will be present I in the upper layers of the interior of the earth. 3. Due to extreme heat and pressure, the rocks must be melting in the interior of the earth. 4. Due to the melting of the rocks, magma will be created in the interior of the earth. 5. Due to endogenous movements in the interior of the earth, volcanic eruptions will occur on the surface of the earth. 6. The primary earthquake waves will be travelling through the mantle and the core of the earth. 7. The secondary earthquake waves will be travelling only through the mantle of the earth. 8. The temperature in the interior of the earth will get increased with the depth. 9. The highest temperature will be found at the centre of the earth. 10. The elements like silica, aluminium, magnesium, iron and nickel will be found in the various layers of the interior of the earth.In simple words: Imagining the Earth's interior reveals intense heat, with temperatures rising significantly towards the center. It consists of massive rocks, some melting into magma due to heat and pressure, driving internal movements that cause volcanic eruptions and earthquakes, with specific elements distributed across its distinct layers.

🎯 Exam Tip: When describing the Earth's interior, cover key aspects like temperature, state of matter (solid/liquid), composition, and dynamic processes like magma formation and seismic wave propagation.

Open-Ended Question:

Question A.What precautions can be taken to reduce the damage caused by earthquakes?
Answer:The following precautions can be taken to reduce the damage caused by earthquakes: 1. Taking cover under a desk or a table or sturdy piece of furniture to protect oneself. 2. Finding clear spot away from buildings, trees and power lines. Dropping to the ground and staying there until the shaking stops. 3. Switching off the power supply, gas in-home/office, etc. 4. Helping the victims at the earliest.In simple words: To minimize earthquake damage, one should "Drop, Cover, and Hold On" under sturdy objects, move to open areas away from hazards, shut off utilities like gas and electricity, and be ready to assist others once the shaking subsides.

🎯 Exam Tip: Focus on practical, immediate actions for personal safety during an earthquake and steps to prevent further damage or help others post-quake.