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NCERT Solutions for Class 7 Social Science Chapter 2 - Inside Our Earth
Access NCERT Solutions for Class 7 Social Science Geography Chapter 2 – Inside our Earth
What Do You Learn in Class 7 Geography Chapter 2?
Chapter 2 introduces students to what lies in the interior of the earth. Here is an overview of the chapter.
Interior of the Earth
Earth is made up of many concentric layers. The uppermost layer on the earth’s surface is called the crust. It is about 35 km on continental masses and 5km on ocean floors, and is the thinnest layer of all. Silica and Alumina are the main mineral constituents of the continental mass. The oceanic crust mainly has silica and magnesium.
Mantle is another layer which is just beneath the crust and has a depth of 2900 km.
The core is the innermost layer. It mainly comprises iron and nickel, and has a radius of 3500. The core has a very high temperature and pressure.
Rocks and Minerals
A rock is any natural mass of mineral matter that makes up the crust of the earth. A rock can have different size, colour and texture. There are three main types of rocks:
Igneous rock - This type of rock is formed when the molten magma cools down and becomes solid. It is also called primary rock. Igneous rocks also have two types - intrusive and extrusive rocks.
Sedimentary rock - The rocks that roll down, crack and break down into small sediments are transported and deposited by water, wind etc. When these loose sediments compress and become hard, they form layers of rocks called sedimentary rocks. Sandstone is an example of sedimentary rock.
Metamorphic rock - Both igneous and sedimentary rocks can change into metamorphic rock, when there’s high heat and pressure.
Rocks are used for making houses, roads, and other structures. Also, one type of rock can change into another type under specific conditions, and this process is called the rock cycle.
Rocks are made from different minerals. Minerals are naturally occurring substances with certain physical properties and a definite chemical composition. Some of the minerals are fuels such as natural gas, coal and petroleum. Minerals are very useful and important for humankind.
Why is it necessary for students to study Social Science Our Environment Chapter-2 - Inside Our Earth Solutions by Extramarks?
Our Environment textbook focuses on giving students an understanding of the environment they live in. It also talks about the components of the environment, such as man-made components, natural components (air, water, land, and living things), and human components, in great detail. Students also learn about life in various terrains such as temperate grasslands, deserts, etc. Our Environment is an integral part of the Class 7 curriculum because it teaches children about the various aspects of nature.
The practise questions given at the end help students in gauging their understanding of the chapter. These are great from a revision perspective. However, students are often unable to write accurate and to-the-point answers to these questions. This is why they must refer to the NCERT Solutions for Class 7 Geography Chapter 2. The solutions have answers written in simple yet comprehensive manner so that students can understand the reasoning and perform better in exams.
How do the experts at Extramarks help?
The subject experts at Extramarks have given a fair idea of Chapter 2 through their NCERT Solutions, which in turn helps students in securing higher marks in exams. With the help of solutions, students will understand every concept and get to know how to write the answers easily. It is written in an easy to understand language by the subject matter experts. It is a thoroughly researched material made as per the CBSE examination guidelines. When students study from it, they will get an edge over their peers.
NCERT Class 7 Social Science Our Environment Chapterwise Solutions
Students can access NCERT Solutions for Class 7 Social Science Geography for following chapters:
- Chapter 1: Environment
- Chapter 2: Inside Our Earth
- Chapter 3: Our Changing Earth
- Chapter 4: Air
- Chapter 5: Water
- Chapter 6: Natural Vegetation and Wildlife
- Chapter 7: Human Environment - Settlement, Transportation and Communication
- Chapter 8: Human Environment Interactions - The Tropical and The Subtropical Region
- Chapter 9: Life in the Temperate Grasslands
NCERT Solutions for Class 7 Social Science
Extramarks provides NCERT solutions for Social Science and also for other subjects. All the solutions are accessible on the website and Extramarks’ app.
Q.1 Answer the following questions.
(i) What are the three layers of the earth?
(ii) What is a rock?
(iii) Name three types of rocks.
(iv) How are extrusive and intrusive rocks formed?
(v) What do you mean by a rock cycle?
(vi) What are the uses of rocks?
(vii) What are metamorphic rocks?
(i) The three layers of the earth are:
(ii) Any natural mass of mineral matter that makes up the earth’s crust is called rock.
(iii) The three types of rocks are:
- Igneous Rocks
- Sedimentary Rocks
- Metamorphic Rocks
(iv) Rocks that are formed when molten magma solidifies on the earth’s crust are known as extrusive igneous rocks.
Sometimes, the molten magma cools down deep inside the earth’s crust. The rocks so formed are known as intrusive igneous rocks.
(v) The process of transformation of rock from one type to another is known as rock cycle.
(vi) Rocks are very useful to us. They are used for making roads, houses, buildings, bridges, etc. They are also used to make decorative items such as vases, boxes, statues, etc.
(vii) When igneous or sedimentary rocks are subjected to high temperature and pressure, they are converted into metamorphic rocks. For example, clay changes into slate and limestone into marble.
Q.2 (i) What are the minerals most commonly used in the following objects?
(ii) Identify some more objects made up of different minerals.
(a) Karhai – Aluminium
(b) Pan/Tava – Iron
(c) Ornaments – Gold
(d) Bell – Brass
(e) Hammer – Iron
(f) Lamp – Copper/Brass
Some other objects made up of minerals are:
(a) Pencil lead – Graphite
(b) Mirror – Glass
(c) Trash can – Chromite
(d) Wires – Copper
Q.3 Tick the correct answer.
(i) The rock which is made up of molten magma is
(a) Igneous (b) Sedimentary (c) Metamorphic
(ii) The innermost layer of the earth is
(a) Crust (b) Core (c) Mantle
(iii) Gold, petroleum and coal are examples of
(a) Rocks (b) Minerals (c) Fossils
(iv) Rocks which contain fossils are
(a) Sedimentary rocks (b) Metamorphic rocks (c) Igneous rocks
(v) The thinnest layer of the earth is
(a) Crust (b) Mantle (c) Core
(i) (a) Igneous ✓
(ii) (b) Core ✓
(iii) (b) Minerals ✓
(iv) (a) Sedimentary rocks ✓
(v) (a) Crust ✓
Q.4 Match the following.
|(i) Core||(a) Earth’s surface|
|(ii) Minerals||(b) Used for roads and buildings|
|(iii) Rocks||(c) Made of silicon and alumina|
|(iv) Clay||(d) Has definite chemical composition|
|(v) Sial||(e) Innermost layer|
|(f) Changes into slate|
|(g) Process of transformation of the rock|
|(i) Core||(e) Innermost layer|
|(ii) Minerals||(d) Has definite chemical composition|
|(iii) Rocks||(b) Used for roads and buildings|
|(iv) Clay||(f) Changes into slate|
|(v) Sial||(c) Made of silicon and alumina|
Q.5 Give reasons.
(i) We cannot go to the centre of the earth.
(ii) Sedimentary rocks are formed from sediments.
(iii) Limestone is changed into marble.
(i) The centre of the earth is characterised by very high temperature and pressure, which does not allow the survival of any living being. Thus, it is impossible for anyone to reach the centre of the earth.
(ii) Rocks strike each other and are broken down into small sediments. These sediments are transported and deposited by natural agents like wind, water, etc. Overtime, these loose sediments are compressed and hardened to form rocks, which are known as sedimentary rocks.
(iii) When igneous and sedimentary rocks are subjected to high temperature and pressure, they are converted into metamorphic rocks. Limestone is a sedimentary rock, which after going through such a process is converted into marble, a metamorphic rock.
FAQs (Frequently Asked Questions)
The crust, mantle, and core make up the interior of the Earth. Various sorts of rocks make up the earth’s crust. Igneous rocks, sedimentary rocks, and metamorphic rocks are the three major types of rocks.
Extrusive rocks are formed when molten lava reaches the surface of the earth and cools down rapidly, forming a piece of rock. Basalt is an example of extrusive rock.
Intrusive rocks are formed when molten lava becomes solid inside the Earth’s crust. Granite is an example of intrusive rock.
Rocks are used for:
- To make roads
- To construct buildings
- To prepare fertilizers
- Different types of games played by children