NCERT Class 9 Social Science Important Chapter 2 Shaping of the Earth’s Surface Solutions English Medium As Per New Syllabus. NCERT Class 9 Social Science Important Chapter 2 Shaping of the Earth’s Surface Notes to each chapter is provided in the list so that you can easily browse throughout different chapter NCERT Class 9 Social Science Additional Question Answer Download PDF and select needs one. CBSE Class 9 Social Science Additional Solutions.
NCERT Class 9 Social Science Important Chapter 2 Shaping of the Earth’s Surface
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Shaping of the Earth’s Surface
Chapter – 2
| Part – I: Geography |
| Important Question Answer |
A. Fill in the Blanks
1. The movement of tectonic plates is mainly caused by __________ currents in the mantle.
Ans: Convection.
2. The rigid outer layer consisting of the crust and the upper mantle is called the __________.
Ans: Lithosphere.
3. Weathering breaks rocks into smaller pieces without the __________ of the broken material.
Ans: Movement.
4. A __________ is formed at the mouth of a river due to the deposition of sediments.
Ans: Delta.
5. Moraines are formed by the deposition of materials carried by __________.
Ans: Glaciers.
B. True or False
1. The asthenosphere is a rigid layer that prevents tectonic plates from moving.
Ans: False.
2. Most earthquakes and volcanoes occur along plate boundaries.
Ans: True.
3. Chemical weathering occurs due to reactions between minerals and substances like water, air, or acids.
Ans: True.
4. Beaches are formed only by volcanic eruptions.
Ans: False.
5. Glaciers are an important source of fresh water for many rivers.
Ans: True.
D. Short Answer Questions
1. Why is the theory of plate tectonics important for understanding the Earth’s surface?
Ans: The theory of plate tectonics explains how the movement of tectonic plates forms mountains, valleys, volcanoes, and oceans. It also helps explain earthquakes and other natural phenomena that continuously reshape the Earth’s surface.
2. How do convection currents cause tectonic plates to move?
Ans: Heat from the Earth’s core causes hot molten material in the mantle to rise while cooler material sinks. These convection currents push and pull tectonic plates, causing them to move slowly.
3. Differentiate between weathering and erosion.
Ans: Weathering is the breaking down of rocks into smaller pieces without moving them, whereas erosion involves both the wearing away and transportation of rock and soil by natural agents such as water, wind, ice, and waves.
4. Why are deltas important for human life?
Ans: Deltas contain fertile alluvial soil suitable for agriculture. They also support fishing, trade, transportation, and dense human settlements because of their rich natural resources.
5. Explain one way in which waterfalls benefit humans.
Ans: Waterfalls help generate hydroelectric power by using the force of falling water. They also attract tourists and provide opportunities for recreation.
6. How do meanders influence agriculture and settlements?
Ans: Meanders deposit fertile soil along river banks, making the surrounding land suitable for farming. Their gentle slopes also encourage the growth of villages and towns.
7. Why are beaches considered important coastal landforms?
Ans: Beaches promote tourism, support fishing activities, provide recreational spaces, and act as natural barriers that protect coastal settlements from strong waves and erosion.
8. How do glaciers contribute to human life apart from shaping landforms?
Ans: Glaciers provide fresh water by feeding rivers, create fertile soils in some valleys, and support tourism, fishing, irrigation, and hydroelectric power through glacial landforms and moraines.
D. Long Answer Questions
1. Explain the formation and effects of the three types of plate boundaries.
Ans: Plate boundaries are places where tectonic plates meet. At convergent boundaries, plates move towards each other, forming fold mountains, volcanoes, and earthquakes. At divergent boundaries, plates move apart, allowing magma to rise and create new crust and mid-ocean ridges. At transform boundaries, plates slide past one another, producing earthquakes without creating or destroying crust. These plate movements continuously reshape the Earth’s surface and are responsible for many natural disasters.
2. Describe the process of weathering and explain its different types.
Ans: Weathering is the process by which rocks break down into smaller pieces without being transported. Physical weathering occurs due to temperature changes, frost, wind, and water. Chemical weathering happens when minerals react with water, air, or acids, producing new substances. Biological weathering is caused by plants, animals, and microorganisms, such as plant roots growing into rock cracks. Weathering contributes to soil formation and prepares rocks for erosion.
3. Discuss the importance of erosion and its impact on human activities.
Ans: Erosion is the removal and transportation of weathered materials by water, wind, glaciers, waves, and other natural agents. It shapes landforms such as valleys, cliffs, and plains. However, erosion can remove fertile topsoil, reduce agricultural productivity, damage roads, houses, and infrastructure, and create safety risks for construction and mining. It also affects tourism and fishing by changing natural landscapes.
4. Explain how rivers create different landforms during their journey from source to mouth.
Ans: Rivers continuously shape the landscape through erosion, transportation, and deposition. In the upper course, they create V-shaped valleys, rapids, and waterfalls through strong erosion. In the middle course, reduced velocity forms meanders, oxbow lakes, and floodplains through lateral erosion and deposition. In the lower course, rivers deposit large quantities of sediments to form deltas, levees, and alluvial fans. These landforms support agriculture, settlements, transportation, and ecosystems.
5. Describe the role of glaciers, wind, and sea waves in shaping the Earth’s surface.
Ans: Glaciers carve U-shaped valleys, cirques, hanging valleys, fjords, and moraines through erosion and deposition. Wind creates yardangs, ventifacts, deflation hollows, desert pavements, and dunes by carrying and depositing sand. Sea waves continuously erode and deposit materials along coastlines, forming beaches, sea cliffs, wave-cut platforms, caves, arches, stacks, and sand bars. These landforms support tourism, agriculture, fishing, transportation, and coastal protection while constantly modifying the Earth’s surface.
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