RBSE Solutions For Class 10 Science Chapter 15: Structure of Earth | Textbook Important Questions & Answers

The distance of the earth from the sun is about 15 crore kilometres. This distance is also called the astronomical unit. The earth is constantly in motion. It rotates on its axis in a day, forming day and night. On the part where sunlight falls, there is the day, and on the part where sunlight does not fall, there is night. Earth revolves around the sun in one year. Earth does not stand straight on its axis, but it is 23.5 degrees inclined. That is why the sun is in the state of uttarayan (Summer solstice) and dakshinayan (Winter solstice) and seasons are formed on earth. These qualities make the earth special from the point of view of life.

Textbook Solutions of RBSE Class 10 Science Chapter 15 are created by the subject experts after going through rigorous research. The solutions are provided in step by step format so that students can understand them easily. By going through the RBSE Class 10 solutions, students will acquire a conceptual understanding of the topic. They can find out the easy way of solving the questions. The textbook solutions will help students in preparing well for the exams.

RBSE Class 10 Science Chapter 15: Objective Textbook Questions and Solutions

Q1. Which one is not the name of earth?

(A) Bhoomi

(B) Gaiy

(C) Bhanu

(D) Tera

Answer: C

Q2. At present how much part of the earth’s surface is covered with water?

(A) 70%

(B) 30%

(C) 50%

(D) Uncertain

Answer: A

Q3. The most abundant element found on earth?

(A) Silicon

(B) Gold

(C) Oxygen

(D) Iron

Answer: D

Q4. Where was the largest harbor of Harappan civilization found?

(A) Dwarka

(B) Dholavira

(C) Surat

(D) Karnavati

Answer: B

Q5. What is reason for the occurrence of tides?

(A) Sun

(B) Moon

(C) Both

(D) Sun and Moon being in a straight line.

Answer: D

RBSE Class 10 Science Chapter 15: Very Short Type Textbook Questions and Solutions

Q6. What is the reason for Sun being in the state of Uttarayan – dakshinayan?

Answer: The reason for Sun being in the state of Uttarayan – dakshinayan is Earth’s tilt on its axis.

Q7. What is the unit of measuring an earthquake?

Answer: Earthquake is one of the effects of internal tectonic forces. Earthquake means the shaking of earth ‘s surface.The intensity of an earthquake is expressed on the Richter scale.

Q8. Where are tectonic plates found?

Answer: Tectonic plates are found in the crust of the Earth. Tectonic powers are of two types

  • Internal Tectonic powers
  • External Tectonic powers

Q9. What is the reason for tsunami?

Answer: Earthquakes generate tsunamis. It must be noted that they can be generated only through the vertical movement of the sea floor. Tsunamis can also be generated by landslides and even volcanic activity too.

Q10. Which types of wind arise due to decreasing air pressure in the centre?

Answer: Cyclones arise due to decreasing air pressure in the centre.

RBSE Class 10 Science Chapter 15: Short Type Textbook Questions and Solutions

Q11.What will be the condition of a place after an earthquake of the magnitude of 7 on the richter scale has hit?

Answer: An earthquake of the magnitude of 7 on Richter scale can be highly devastating. It usually causes immense damage to houses and buildings. Landslides also happen in case of powerful earthquakes. It can result in loss of life and property.

Q12. What are oceanic currents?

Answer: Oceanic currents can also be called a river flowing in the sea. In this, the water flows continuously in a certain direction. In some oceanic currents warm water flows while in some the cold water. The reason for the flow of the oceanic current is not due to the slope but because of the difference in the inter temperature density. These currents have a great effect on human life.

Q13. What are the advantages of weathering forces in agriculture?

Answer: The forces of weathering have proved to be very useful from the point of agriculture. Soil is very important for agriculture and it is formed by the forces of weathering. Their role in the construction of plains for agriculture is important. Many types of chemicals come out of the rocks due to weathering.

Q14. Name four causes which help in weathering.

Answer: The four causes which help in weathering are:

  • Temperature
  • Rain
  • Snow
  • Wind

Q15. How was the moon born?

Answer: Moon was formed 4.40 million years ago by the collusion of an object the size of Mars with earth. Moon is earth’s only natural satellite. By its attraction power it produces marine tides, helps the earth bend properly on its axis, and slows down the rotation of the earth.

Q16. What do you understand by Richter Scale?

Answer: The Richter magnitude scale (also Richter scale) assigns a magnitude number to quantify the energy released by an earthquake. The Richter scale, developed in the 1930s, is a base-10 logarithmic scale, which defines magnitude as the logarithm of the ratio of the amplitude of the seismic waves to an arbitrary, minor amplitude.

Q17. Write a short note on Earth’s crust?

Answer: The crust is the outermost solid part of the earth. It is fragile in nature. The thickness of the crust varies under the oceanic and continental areas. Oceanic crust is thinner as compared to the continental crust. The continental crust is thicker in the areas of major mountain systems. The crust is made up of heavier rocks having a density of 3 g/cm3. The kind of rock seen in the oceanic crust is basalt. The mean density of material in the oceanic crust is 2.7 g/cm3.

Q18. Write a short note on Earth’s mantle?

Answer: The portion of the interior beyond the crust is called the mantle. It is in a solid state.

It has a density higher than the crust portion. The thickness ranges from 10-200 km. The mantle extends from Moho’s discontinuity to a depth of 2,900 km. The asthenosphere is the upper portion of Mantle. It is the chief source of magma that finds its way to the surface during volcanic eruptions. The crust and the uppermost part of the mantle are called lithosphere.

Q19. Write a short note on Earth’s core?

Answer: The core-mantle boundary is positioned at the depth of 2,900 km. The inner core is in the solid state whereas the outer core is in the liquid state. The core is made up of very heavy material mostly constituted by nickel and iron. Hence, it is also called the “nife” layer.

Q20. What is a volcano?

Answer: A volcano is a vent or fissure in Earth’s crust through which lava, ash, rocks, and gases erupt. An active volcano is a volcano that has erupted in the recent past. The mantle contains a weaker zone known as the asthenosphere. Magma is the material present in the asthenosphere. Material that flows to or reaches the ground comprises lava flows, volcanic bombs, pyroclastic debris, dust, ash and gases. The gases may be sulphur compounds, nitrogen compounds, and trace amounts of argon, hydrogen and chlorine.

Q21. Write a short note on Tsunami?

Answer: The word Tsunami literally means ‘ harbour wave’. They can be described as a series of waves. The characteristic feature that differentiates these waves is their long wavelength.

Earthquakes generate tsunamis. It must be noted that they can be generated only through the vertical movement of the sea floor. Tsunamis can also be generated by landslides and even volcanic activity too.

Q22. Write a short note on glaciers.

Answer: Glaciers are a bulk of ice moving under its own weight. It forms in areas where the amassing of snow goes beyond its ablation over many years. They are generally seen in the snow-fields. This largest freshwater basin covers around 10 percent of the land surface of the Earth. According to the topography and the location of the glacier, it can be categorized as Mountain Glacier (Alpine Glaciers) or Continental Glacier (Ice Sheets). The Continental Glacier moves outward in all directions whereas the Mountain Glacier moves from a higher to a lower altitude.

Q23. State the difference between weathering and erosion?

Answer: The difference between weathering and erosion are:

Erosion Weathering
It is the displacement of solids by wind, water and ice. It is the decomposition of rocks, soil and minerals by direct contact with the atmosphere.
The eroded materials are displaced. The weathered materials are not displaced.
The different types of erosion are water, wind, ice, thermal and gravity erosion The different types of weathering include physical, chemical and biological weathering
Wind, water, ice and human activities are some of the causes of erosion. Weathering is caused due to atmospheric factors like air pressure.

Q24. How is tide formed?

Answer: Tide is formed when the sun and the moon are in a straight line. Due to the increase in the gravitational force on the sea water, the tides form.

Q25. What is called wind?

Answer: Air flows from the region of high pressure to the region of low pressure. Blowing air is called wind. The direction of wind on land is not always the same. Their direction changes according to the season. At the time of a cyclone the winds do not go straight but move towards the central point in a circular path. This happens due to the reduced air pressure at the centre.

RBSE Class 10 Science Chapter 15: Essay Type Textbook Questions and Solutions

Q26. Explain the internal structure of the Earth. Also draw a well-labelled diagram.

Answer: Our Earth consists of four different layers namely:

  • Inner core
  • Outer core
  • Mantle
  • Crust

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 with temperature up to 5,500Co. Due to its immense heat energy, the inner core is more like the engine room of the Earth.

Outer Core – The outer core of the Earth is similar to a very hot ball of metals, whose temperature is around 4000Fo to 9000Fo. It is so hot that the metals inside are all in the liquid state. The outer core is located around 1800 miles under the crust and approximately 1400 miles thick. It is composed of metals such as iron and nickel. The outer core surrounds the inner core. The inner core has pressures and temperatures so high that the metals are squeezed together and not able to move like a liquid, but are forced to vibrate instead of solid.

Mantle – Mantle is the widest section of the Earth. Its thickness is approximately 2,900 km. 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 is located directly under the Sima. The mantle consists of very hot and dense rock. This layer of rock flows like asphalt under heavy weight. This flow is because of the greatest temperature differences from the bottom to the top of the mantle. The reason behind the plates of the Earth moving is called the movement of the mantle. Its temperature varies between 1600 oF at the upper part to 4000 oF near the bottom.

Crust – The crust is the outer layer where we live. The thickness is around 0-60 km. It’s a solid rock layer divided into two types:

  • Continental crust covers the land and
  • Oceanic crust covers water.

The crust is the most widely studied and understood. Mantle is hotter and capable of flowing. The outer and inner core are much hotter with great pressures that you can be squeezed into a ball smaller than a marble if you are able to go in the center of the Earth.

RBSE Class 10 Science Chapter 15 - 16

Q27. What do you mean by Earth’s tectonic powers? Describe any two?

Answer: Several types of rocks work continuously to change the surface of the earth. These powers are called the tectonic powers. Tectonic powers are of two types. – Internal tectonic powers and External tectonic powers.

Internal tectonic powers – These forces work by staying inside the earth and can not be seen from outside. Their origin is due to the spreading of the rocks by molten, below the surface of the earth and also due to the shifting of the magma. When the internal tectonic forces work vertically to the earth’s centre, some part of the surface of earth rises and some others are submerged, thus the continents, islands, plateaus, plains, oceans, etc are formed. Sedimentary rocks are formed inside the seas rise and move towards continents. Waves are produced when the internal tectonic forces work horizontally. Due to these waves there is a huge upheaval of the rocks found on the earth surface. Folds and cracks are formed on the surface, valleys and mountains are also formed

External tectonic powers – Based on the method of work, the external tectonic forces can be divided into two parts. In the first group there are forces that work only by staying at its place. They have no speed but by initial preparation they help the second group of tectonic powers. First group of external tectonic powers are called weathering forces. Second type of forces which move from its place are called erosional forces.

Q28. What is erosion? Explain the importance of the two types of erosion powers on human life.

Answer: Soil Erosion is one form of soil degradation. It occurs in almost all types of lands. Flowing water, rainwater, and the wind are the prime agents which cause a significant amount of soil loss each year. Too much soil erosion causes serious loss of topsoil and also reduces crop production potential, lower surface water quality, and damaged drainage networks.

Significance of wind on human life:

  • It causes changes in weather and thus affects our life in significant ways.
  • Helps in navigation of ships.
  • It’s energy is being harnessed to produce electricity.
  • It changes the landform around us.

Significance of river:

  • River changes the landform along its course.
  • Rivers have always played an important role in the development of human civilization and many great civilizations have flourished along rivers.
  • River brings flood which may cause havoc.
  • River serves as an important channel for transport.

Q29. What is an Earthquake and how is it caused?

Answer: An earthquake is the shaking of the surface of Earth due to the sudden release of energy in the Earth’s crust, as a result, seismic waves (also known as S waves) are created. The seismic activities in an area determine the type and intensity of the earthquake.

Earthquakes are caused due to sudden tectonic movements in the earth’s crust. When the tectonic plates slide over one another, there is a cause of orogeny which results in earthquakes and volcanoes. These disturbances cause vibrations which spread in all the directions. As there is a relative motion of these plates, there is stress built up, which breaks by releasing the stored energy known as shock waves.

Following are the effects of the earthquake:

  • Ground shaking: Surface waves that are near the epicentre are responsible for the earthquake. The intensity of ground shaking depends on the duration, local geology and distance.
  • Damage to a man-made structure.
  • An outbreak of fire and spilling of hazardous chemicals.

Q30. Explain the causes of soil erosion?

Answer: Following are the important causes of soil erosion:

Rainfall and Flooding – Higher intensity of rainstorm is the main cause of soil erosion. Four types of soil erosion are caused by rainfall:

  • Rill erosion
  • Gully erosion
  • Sheet erosion
  • Splash erosion

The raindrops disperse the soil which is then washed away into the nearby streams and rivers. Regions with very heavy and frequent rainfall face a large amount of soil loss. The flowing water during floods also erodes a lot of soil by creating potholes, rock-cut basins, etc.

Agriculture – The farming practices are the major cause of soil erosion. The agricultural activities disturb the ground. The trees are cleared and the land is ploughed to sow new seeds. Since most of the crops are grown during the spring season, the land lies fallow during winters. Most of the soil is eroded during winters. Also, the tyres of tractors make grooves on the land making a natural pathway for water. Fine soil particles are eroded by wind.

Grazing – The grazing animals feed on the grasses and remove the vegetation from the land. Their hooves churn up the soil. They also pull out plants by their roots. This loosens the soil and makes it more prone to erosion.

Logging and Mining – A large number of trees are cut down to carry out the logging process. Trees hold the soil firmly. The canopy of the trees protects the soil from heavy rainfall. The leaf litter that protects the soil from erosion, is also lost during logging. Mining activities also disturb the land and leave the soil more prone to erosion.

Construction – The construction of roads and buildings exposes the soil to erosion. The forests and grasslands are cleared for construction purposes, which exposes the soil making it vulnerable to erosion.

Rivers and Streams – The flowing rivers and streams carry away the soil particles leading to a V-shaped erosion activity.

Heavy Winds – During dry weather or in semi-arid regions, the minute soil particles are carried away by wind to faraway lands. This degrades the soil and results in desertification.

Q31. How can we prevent soil erosion?

Answer: Soil erosion is a serious environmental issue. Steps should be taken to curb this problem. Following are some of the methods of soil erosion prevention:

  • Plant trees on barren lands to limit erosion of soil.
  • Add mulch and rocks to prevent the plants and grass underneath to prevent soil erosion.
  • Mulch matting can be used to reduce erosion on the slopes.
  • Put a series of fibre logs to prevent any water or soil from washing away.
  • A wall at the base of the slope can help in preventing the soil from eroding.
  • Every household should have a proper drainage system so that water flows down into proper water collecting systems.

Q32. What is a tide? Explain types of tides?

Answer: Tides can be defined as the alternate rise and fall of the ocean water. It is caused by the combined effects of :

  • Gravitational force exerted on Earth by the Sun
  • Gravitational force exerted on Earth by the Moon
  • Rotation of the Earth

Types of Tides

Diurnal Tides: It means four tides in a day. Two tides by the sun and two by the moon.

Spring Tide: It is an exceptionally high tide generated by the complementary factor played by the Sun with respect to the moon. It should be noted that when Sun, moon and Earth are in the same line, the position is known as the Syzygy.

Neap Tide: This tide occurs during the first and the last quarter of the moon. It is a comparatively small tide known as the ebb. The magnitude of tide is minimum here.

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