Class 7 Social Science Chapter 2 Interior of the Earth Question Answer in English Medium to each chapter is provided in the list so that you can easily browse throughout different chapters SEBA Class 7 Social Science Chapter 2 Interior of the Earth Notes and select need one.
Class 7 Social Science Chapter 2 Interior of the Earth
Also, you can read the SCERT book online in these sections Solutions by Expert Teachers as per SCERT (CBSE) Book guidelines. These solutions are part of SCERT All Subject Solutions. Here we have given Geography, History, Political Science and Economics Assam Board Class 7 Social Science Chapter 2 Interior of the Earth Solutions for All Subject, You can practice these here.
Interior of the Earth
Chapter – 2
GEOGRAPHY
1. Choose the correct answers:
(a) The earth from its surface to the centre ic composed of 4/3/2/ layers.
Ans: 3 layers.
(b) The earth’s crust is about 20/30/25km thick.
Ans: 20 km thick.
(c) The centre of the earth means crust/mantle/core.
Ans: Core.
(d) Fossils are generally found in Sedimentary /Igneous / Metamorphic rocks.
Ans: Sedimentary rocks.
(e) The hardest mineral is gold/diamond/zinc.
Ans: Diamond.
2. Fill in the blanks –
(a) ______ increases as we go deeper from the crust to the interior of the earth.
Ans: Temperature.
(b) The earth’s crust is also known as _______.
Ans: Lithosphere.
(c) Soil is composed of ______ and ______ matters.
Ans: Organic and inorganic.
(d) Rocks formed due to cooling of magma are called________.
Ans: Igneous rocks.
(e) Minerals are generally _______ materials.
Ans: Inorganic.
3. Write short notes ( in about 30 words)
(a) What do you understand by earth’s crust?
Ans: The solid outer layer of the earth is known as the crust. It is believed that when the liquid and gaseous matters cooled and condensed it lead to the formation of rug- ged and uneven earth’s crust. Actually moun- tains, plateau plains, seas, oceans etc are formed on the earth’s crust. The crust is a thin layer as compared to the other two lay- ers. It is on average around 20 km thick. But the continental part is about 16 km to 60 km thick and the thickness under the ocean floor is only 5 km to 10 km.
(b) What are igneous rocks?
Ans: The hot liquid molten materials in the interior of the earth are called magma. This ‘magma’ which can- not come out the earth’s surface, gradually cools down and solidifies to form rocks. The rocks formed in this way below the surface of the earth are called intrusive igneous rocks.
(c) What is soil?
Ans: Another element of the crust is soil. Soil is the upper most soft layer of the earth’s crust where we build houses, grow crops, develop transport system and plants stand. Soil is formed when rocks are broken into pieces and fragments due to the factors like heat, wind, rain and other natural forces.
(d) What are minerals?
Ans: The minerals form another element in the earth’s crust. They are nothing but the inorganic materials formed through natural processes on the earth. The minerals are basically solid substance found on the earth’s crust. All minerals have some distinct properties namely colour, Instre, brightnes etc.
(e) What is “humus”?
Ans: Actual soil is found up to a depth of 3 meters from the Earth’s surface. Soil is formed by organic and inorganic materials. Organic elements of soil refer to humus. The decomposed organic matter, i.e. the remains of dead animals and plants form the humus of the soil. Such organic materials supply nutrients to plants.
4. Write answer (within 100 words)
(a) What are the different layers of the earth from its surface to the centre?
Ans: The different layers of the earth from its surface to the centre are:
(i) Crust: The solid outer layer of the earth is known as the crust. The crust is a thin layer as compared to the other two lay- ers. It is on average around 20 km thick. But the continental part is about 16 km to 60 km thick and the thickness under the ocean floor ienly 5 km to 10 km.
(ii) Mantle: The mantle,the second layer of the interior of the earth which is just below the crust. This layer is about 2,900 km thick. The density of materials of this layer is more than that of the crust. The entire mantle layer is again divided into mantle and the two the upper mar lower mantle.
(iii) Core: The layer below the mantle is called the Core. This layer is about 3,486 km thick. The materials in this layer are in a very hot state. This layer is largely made up of iron, nickel and cobalt. Due to high iron and nickel content this layer is also known as Nife.
(b) Write about the types of rocks with examples.
Ans: The solid crust of the earth is mainly made up of rocks. The layer formed by rocks is known as ‘lithosphere. Generally and relatively the solid hard materials found on the surface of the earth are called rocks.
Here are the different types of rocks:
(i) Igneous rocks: As igneous rocks are formed first on the earth, these are also known as primary rocks. Valuable metals like gold, silver, lead, zinc etc. are also found in these rocks. The examples of igneous rocks. The rocks of Jaintia and Nilachal hills of North East India are examples of Igneous rocks.
(ii) Sedimentary rocks: These rock fragments are carried away by wind, river, glacier, etc. After long continued deposition such sediments become hard due to tremendous pressure and heat, and reaction of iron, lime, etc. present in water. The examples of sedimentary rocks. The rocks of the Himalayas are examples of sedimentary rocks.
(iii) Metamorphic rocks: The igneous and sedimentary rocks under excessive heat and pressure over years long are converted into a new type of rocks due to certain physical and chemical changes. These are called metamorphic rocks. The examples are marble, schist.
(c) Find out the differences between rock and soil.
Ans:
| Rock | Soil |
| The solid crust of the earth is mainly made up of rocks. The layer formed by rocks is known as ‘lithosphere’. Generally and relatively the solid hard materials found on the surface of the earth are called rocks. | Soil is the upper most soft layer of the earth’s crust where we build houses, grow crops, develop transport system and plants stand. |
| Rocks are made up of different kind of minerals. Sane rocks contain variety of minerals and some are made up of a very few minerals. | soil is found up to a depth of 3 meters from the Earth’s surface. Soil is formed by organic and inorganic materials. Organic elements of soil refer to humus. |
| Among the chemical sub- stances, oxygen, silicon, aluminium, iron, calcium, sodium, potassium, carbon, sul- phur etc. are found in large quantity in rocks. Besides these, some amount of metals like copper, lead, zinc etc. are also found. | On the other hand, the inorganic elements present in the soil are nitrogen, potassium, magnesium, sulphur, phosphorous, calcium, iron, copper, etc. |
(d) “No, plants and animals can survive without soil” – Explain.
Ans: Soil provide nutrients and minerals to the autographs and heterotrophs. Man and animal dependent on plants for there nutrition. Soil plays an important role in biogeochemical cycles.Organic elements of soil refer to humus. The decomposed organic matter, i.e. the remains of dead animals and plants form the humus of the soil. Such organic materials supply nutri- ents to plants. Presence of organic elements increases the water retaining capacity of soil. The water in the soil plays an important role in the growth of plants. In this way the life of plants depends on soil and ours and animals life depends on plants.
(e) “The influence of climate is indispensable in the format of soil”- Explain.
Ans: Climate is one of the most important factors affecting the formation of soil. Hotter temperatures and lot of presence of water have a tendency to speed up the formation of soil, And cooler temperatures and less presence of water slow down soil formation.Climate indirectly affects soil formation through its influence on organisms as well. High temperatures and rainfall increase the degree of weathering and therefore the extent of soil development. Increase of rainfall increase organic matter content, decrease pH, increase leaching of basic ions, movement of clay etc.
(f) Find out the relationship between rocks, minerals and soils found on the earth’s crust.
Ans: The solid crust of the earth is mainly made up of rocks. Rocks are made up of different kind of minerals. Sane rocks contain variety of minerals and some are made up of a very few minerals. Depending upon the characteristics of minerals there exists variation in colour, size, hardness and texture of rocks.soil is found up to a depth of 3 meters from the Earth’s surface. Soil is formed by organic and inorganic materials. Organic elements of soil refer to humus.Through the processes of weathering and erosion, rocks change, break, and move. Minerals mix with organic material to form the soil on which plants and animals rely.
5. Name of different types of rocks are given in the box. Classify and write them according to their type in the table below:
| Marble, Slate, Sandstone, Granite, Coal, Limestone, Chalk, Gneiss, Conglomerate, Mudstone, Schist, Quartzite, Basalt and Gabbro. |
| Igneous rock | |
| Sedimentary rock | |
| Metamorphic rock |
Ans:
| Igneous rock | Granite, Basalt and Gabbro. |
| Sedimentary rock | Sandstone, Coal, Limestone, Chalk, Conglomerate and Mudstone. |
| Metamorphic rock | Marble, Slate, Gneiss, Schist and Quartzite. |
