NCERT Solutions for Class 7 Social Science Chapter 3 Our Changing Earth Free PDF Download
1. Answer the following questions.
i. Why do the plates move?
Ans: There is constant generation of energy due to various processes undergoing in the inner layers of the Earth. Due to this amount of heat energy, the plates also move.
ii. What are exogenic and endogenic forces?
Ans: The forces that act on the earth's surface are called exogenic forces while the ones that act in the earth's interior are called endogenic forces.
iii. What is erosion?
Ans: The wearing away of the landscape by various agents like wind, water, and ice is called erosion.
iv. How are flood plains formed?
Ans: Flood plains are formed due to deposition of silt in the region during floods. When water gets out, the silts remain and they form the flood plains.
v. What are sand dunes?
Ans: The small hill-like structures of sand formed due to the action of wind are called sand dunes.
vi. How are beaches formed?
Ans: When sea waves deposit materials on the shores of the sea, beaches are formed.
vii. What are ox-bow lakes?
Ans: When a river changes its course suddenly, an oxbow lake is formed.
2. Tick the correct Answer.
i. Which is not an erosional feature of sea waves?
a) Cliff
b) Beach
c) Sea cave
Ans. (c) Sea Cave
ii. The depositional feature of a glacier is:
a) Flood Plain
b) Beach
c) Moraine
Ans. (c) Moraine
ii. Which is caused by the sudden movements of the earth?
a) Volcano
b) Folding
c) Flood Plain
Ans. (a) Volcano
iii. Mushroom rocks are found in:
a) Deserts
b) River valleys
c) Glaciers
Ans: (a) Deserts
iv. Ox bow lakes are found in:
a) Glaciers
b) River valleys
c) Deserts
Ans: (b) River valleys
3. Match the following.
Ans:
4. Give reasons.
i. Some rocks have a shape of a mushroom.
Ans: It is because they are formed when the winds erode the lower part of a rock more than the upper part.
ii. Flood plains are very fertile.
Ans: It is because they are formed by sediments of rivers which deposit the fertile land and silt with high mineral content in them.
iii. Sea caves are turned into stacks.
Ans: It is because over the time of erosion, the structure gets changed from cracks to stacks.
iv. Buildings collapse due to earthquakes.
Ans: It is because the earthquakes are shock waves which damage the foundations of the buildings.
5. Observe the photographs given below. These are various features made by a river. Identify them and also tell whether they are erosional or depositional or landforms formed by both. Photograph Name of the Feature Type (Erosional or Depositional or Both)
Ans:
6. Solve the crossword puzzle with the help of given clues.
Ans:
Benefits of NCERT Solutions of Chapter 3 Our Changing Earth Class 7 Social Science
Here we will check what are the benefits of studying the NCERT Solutions of Chapter 3 Our Changing Earth of Class 7 Social Science Geography.
NCERT Solutions of Class 7 Chapter 3 Social Science will help the students to understand the chapter from the point of view of the Class 12 CBSE exam.
The students get to prepare the questions and answers as per the CBSE guideline.
NCERT Solutions of Chapter 3 will also help the students to revise the chapter as a whole.
These solutions act as a guide that helps the students to know what type of questions and answers can come in the exam from this chapter and thus they prepare accordingly.
With these NCERT Solutions, students will get to know the important topics which are to be studied on a priority basis.
Topics Covered in NCERT Solutions for Chapter 3 Our Changing Earth Class 7 Social Science
Chapter 3, Our Changing Earth consists of the following topics.
Introduction to Lithospheric plates
Forces that cause movement of the earth
Volcano
Earthquake
A case study of earthquake
Major landforms
Rivers
Sea waves
Ice
Wind
NCERT Solutions of Chapter 3 ‘Our Changing Earth’ (Class 7 Social Science) - Key Points at a Glance
The following are the important points that are discussed in the NCERT Solutions Chapter 3 Class 7 Social Science Our Changing World.
The Lithospheric plates are defined as a set of plates that make up the lithosphere.
The movement of molten magma inside the earth causes the relatively slow movement of lithospheric plates.
Earth movements are classified according to their causes.
Endogenic and Exogenic forces are the names given to these forces.
Endogenic forces are those that operate within the earth's interior.
Exogenic forces are the forces that operate on the earth's surface.
A volcano is defined as a sudden eruption of molten rock through some kind of crack in the earth's crust.
Earthquakes are caused by the movement of lithospheric plates, which causes the earth's surface to shake and shift about.
Weathering and erosion are two processes that wear the landscape down over time.
NCERT Solutions of Chapter 3 ‘Our Changing Earth’ (Class 7 Social Science) -
An Overview of the NCERT Class 7 Geography Chapter 3 Notes
The class 7 geography chapter 3 notes consist of different aspects of the geography and our earth movement. Let us earth movements and their names-
Lithospheric Plates: The lithospheric plate is broken into a different number of plates and keeps moving around very slowly because of the movement of the molten magma inside the earth. This molten magma inside the earth keeps moving circularly. These movements are further divided based on forces called Endogenic and Exogenic forces. Endogenic forces act in the interior of the earth called the Endogenic forces producing sudden movements resulting in earthquake and volcano eruption. Exogenic forces work on the surface of the earth and are called the Exogamic forces.
Volcano: Volcano is the vent in the earth's crust through which the molten material erupts.
Earthquake: Earthquake happens when lithospheric plates move, resulting in the vibration of the earth travelling around the earth.
Epicentre: Epicentre is the surface where the actual movement happens. From the epicentre, vibration travels to other locations in the form in the form of waves. When the earthquake occurs, the epicentre is where the majority of the damage happens.
Major Landforms: In the NCERT class 7 geography chapter 3 notes, subject experts provide complete information about how the landscape wore out in two different processes- weathering and erosion.
Weathering means the breaking up of rocks on the earth's surface.
Erosion is a method of the landscape by different agents like water, wind and ice. Material that is eroded is carried away by water and wind. These two processes of erosion and deposition lead to the creation of different landforms.
Work of Sea Waves
Soil and land are not the two only things that lead to a changing environment, but also change in sea waves. Below are ways how sea waves change-
Sea Caves: The erosion and deposition result in the coastal landforms and keep striking rocks leading to cracks. Over the period, these cracks keep growing.
Sea Arches: Arches happen, when cavities in the rock get bigger.
Sea Cliff- Seacliff is a steep rocky coast, which keeps rising, in the vertical form and different shapes.
Work of Wind
Besides, sea and land, the wind too plays a vital role in changing the landforms. The wind that blows in the desert acts as the active agent in erosion and deposition. Sand dunes, on the other hand, happen when win blows, it transports the sand from one place to another. When the wind stops blowing, and sand settles down, the area is then called as the sand dunes.
NCERT Class 7 Social Science Our Environment Chapterwise Solutions
Chapter 7 - Human Environment-Settlement, Transport and Communication
Chapter 8 - Human Environment Interactions - The Tropical and the Subtropical Region
NCERT Solutions for Class 7 Social Science Books Available for
NCERT Solutions for Class 7 Social Science - Social and Political Life (Civics)
NCERT Solutions for Class 7 Social Science - Our Pasts-2 (History)
NCERT Solutions for Class 7 Social Science - Our Environment (Geography)
Class 7 students who are looking for NCERT class 7 geography chapter 3 notes can now download this chapter in PDF format. The PDF format is straightforward to download and learn about the subject. Students do not have to keep looking for different sources to download and learn about the chapter. The best part of downloading this chapter from the reputed website is you get truthful information about a specific subject.
Conclusion
Vedantu's NCERT Solutions for Class 7 Social Science Chapter 3 - "Our Changing Earth" provide an invaluable resource for students studying the dynamic processes that shape our planet. These solutions meticulously align with the NCERT curriculum, offering comprehensive coverage of geological phenomena, such as earthquakes, volcanoes, and weathering. They provide clear explanations and insightful answers to enhance students' understanding of these natural processes.
Vedantu's dedication to delivering quality education is evident in these solutions, making them an essential tool for Class 7 students. By utilizing these NCERT Solutions, students can deepen their knowledge of Earth's geological transformations, critical thinking abilities, and overall academic performance, fostering a greater appreciation for the forces that shape our world.
FAQs on NCERT Solutions for Class 7 Social Chapter 3 - Our Changing Earth
1. What are the Different Types of Earth's Forces?
There are different types of earth's forces. The NCERT class 7 of chapter 3 notes provides complete information on the same.
Earth's movements are divided according to the basis of the forces causing different issues.
Forces acting in the interior of the earth are called endogenic forces and those that work on the surface of the earth are called exogenic forces. In many cases, these endogenic forces produce sudden movements, and in some time, they produce slow movements. These sudden movements lead to volcanoes.
2. How to Prepare to be Safe During the Earthquake?
An earthquake can take place anytime, and you need to be well prepared to ensure that there is no harm. Some of the ways to be protective are-
Find a safe spot at home like a kitchen counter, table or desk
Stay away from fireplaces and windows
Stay away from ceiling fans and hanging lights as they can fall easily
Reach out to the open space and be with the crowd
We should be able to face the disaster
3. What are the Coastal Processes?
Coastal zone is the part of the surface land, which is widely influenced by the marine process. Coastal zone plays an active part in the earth's surface, where marine and atmospheric processes produce coastal rocks, along with beaches and dunes. These coasts also support rich ecosystems like mangroves, coral reefs and salt marshes. Waves, on the other hand, provide half the energy at the cost. Ocean waves are usually generated through wind blowing. Stronger the wind, longer the waves blow.
4. What do you know about the lithospheric plates according to Chapter 3 of Class 7 Social Science?
When the regions of Earth's crust and upper mantle of the lithosphere are fractured into numerous plates, these plates are known as lithospheric plates. Now, due to the movement of molten magma inside Earth's crust, these plates also keep moving slowly. The changes caused on the surface of Earth are all due to the movement of these lithospheric plates. The sudden movements of these lithospheric plates destroy Earth in the form of Volcanoes, Earthquakes, etc.
5. How do the lithospheric plates move as discussed in Chapter 3 of Class 7 Social Science?
Movements in the lithospheric plates occur due to heat produced in the Earth's core because of convection currents in the mantle part of the Earth. When the warmer material rises, the material which is colder sinks down, and this pattern of rising and sinking keeps on repeating over and over again, thus causing the lithospheric plates to rise and become a reason for their movement. To learn more about this chapter visit Vedantu’s website (vedantu.com). Any study material is available to download absolutely free of cost.
6. Explain the working of a river as explained in Chapter 3 of Class 7 Social Science.
The river's flowing water erodes the landscape. A waterfall is formed when a river flows at a steep angle over exceptionally hard rocks or down a deep valley side. The river twists and turns as it enters the plains, forming huge bends known as meanders. The ends of the meander loop are getting closer and closer due to constant erosion and deposition along the meander's sides.
The meander loop eventually separates from the river and forms a cut-off lake, also known as an ox-bow lake. The river occasionally breaches its banks, producing flooding in the surrounding areas. It deposits sediments along its banks as it floods, which are layers of fine dirt and other debris.
7. Give an account of the working of wind as discussed in Chapter 3 of Class 7 Social Science.
In deserts, the wind is a major cause of erosion and deposition. Mushroom rocks are rocks that have the shape of a mushroom and are commonly found in deserts. The lower section of the rock is eroded more by the wind than the higher section. As a result, such rocks have a smaller base and a larger top. The wind lifts and moves sand from one location to another when it blows.
Sand falls and is deposited in low hill-like structures when the wind stops blowing. They are known as dunes. When grains are very fine and light, they can be carried over long distances by the wind. Loess is the name given to sand that has been deposited over a broad area.
8. Give an account of earthquake preparedness according to Chapter 3 of Class 7 Social Science.
An earthquake is a natural disaster that we cannot prevent. However, if we are prepared ahead of time, we can lessen the impact. We should move to a safe location in the event of an earthquake. We should hide behind a kitchen counter, table, or desk against a door or a wall on the inside. We should avoid fireplaces, locations around chimneys, and windows with reflective surfaces, such as mirrors and picture frames. Furthermore, we should make our friends and family members aware of the situation.