RBSE Solutions for Class 7 Social Science Geography Chapter 2 Inside Our Earth

Rajasthan Board RBSE Solutions for Class 7 Social Science Geography Chapter 2 Inside Our Earth Textbook Exercise Questions and Answers.

RBSE Class 7 Social Science Solutions Geography Chapter 2 Inside Our Earth

RBSE Class 7 Social Science Inside Our Earth InText Questions and Answers

Page 9 

Question 1. 
Collect pictures of some monu¬ments and find out which are the rocks used to huild them.
Answer:
To be done by the students.
Hint: 

1. Red fort: Red sandstone, 
2. Tajmahal: Marble, 
3. Jantar Mantar: Clay bricks made up of Shale, 
4. Hawa Mahal: Sandstone, 
5. Ajanta Ellora Caves: Massive basalt

RBSE Class 7 Social Science Inside Our Earth Textbook Questions and Answers  

Question 1.
Answer the following question.
(i) What are the three layers of the earth?
Answer:
(a) Core: At the centre of the earth lies the core - a dense mass of liquid iron and nickel (Nife) that is solid at very centre.
(b) Mantle: Enclosing the metallic core is the mantle, composed of Silica and Magnesium.
(c) Crust: The outermost layer is the crust. Lithosphere the outermost sheet of rigid, brittle rocks, includes the crust.

(ii) What is a rock?
Answer:
A rock is an assemblage of minerals in the solid state in wide range of composition, physical characteristic and ages.

(iii) Name three types of rocks.
Answer:
(a) Igneous rocks,
(b) Sedimentary rocks,
(c) Metamorphic rocks.

(iv) How are extrusive and intrusive rocks formed?
Answer:
Extrusive rocks: When the molten lava comes on the earth’s surface, it quickly cools down and takes a solid form. Rocks formed in this manner are called as extrusive igneous rocks. Intrusive rocks: Sometimes, the molten magma cools down deep inside the earth’s crust. Solid rocks so formed are called intrusive igneous rocks.

(v) What do you mean by rock cycle? 
Answer:
Rock cycle links sedimentary, metamorphic and igneous rocks in the processes of rock formation and destruction.. The three class of rocks are transformed into one another by weathering and erosion and exposure to heat and pressure. This is called as Rock Cyde.

(vi) What are the uses of rocks? 
Answer:
Rocks are used for various purposes like: '
(a) Stones, slates, granite, etc. are used for building houses, bridges, embankments etc.
(b) Rocks formed from peat or other organic deposits may be burned as fuel.
(c) Rocks make one of the principle composition of earth’s crust.
(d) They are used in various games like Pithoo, Seven stones, etc.

(vii) What are metamorphic rocks? 
Answer:
Metamorphic rocks are formed when igneous or sedimentary rocks are exposed to heat and pressure. Clay is altered to slate, sandstone and becomes quartzite and intrusive igneous rocks are metamorphosed into granite

Question 2. 
Tick the correct answer
(i) The rock which is made up of molten magma is:
(a) Igneous 
(b) Sedimentary 
(c) Metamorphic
Answer:
(a) Igneous 

(ii) The innermost layer of the earth is:
(a) Crust
(b) Core
(c) Mantle
Answer:
(b) Core

(iii) Gold, petroleum and coal are examples of:
(a) Rocks 
(b) Minerals
(c) Fossils
Answer:
(b) Minerals

(iv) Rocks which contain fossils are:
(a) Sedimentary rocks
(b) Metamorphic rocks
(c) Igneous rocks
Answer:
(a) Sedimentary rocks

(v) The thinnest layer of the earth is:
(a) Crust
(b) Mantle
(c) Core
Answer:
(a) Crust

Question 3. 
Match the following

Answer:

Question 4. 
Give reasons v.
(i) We cannot go to the centre of the earth. vv
Answer:
To reach the centre-of the earth, one have to dig a hole 6000 km. deep on the ocean floor which is not possible. The core has very high temperature, and pressure. Therefore we cannot go to the centre of the earth.
 
(ii) Sedimentary rocks are formed from sediments.
Answer:
Rocks roll down, crack and hit each other and are broken down into small fragments known as sediments. These sediments are transported and deposited by wind, air water etc. These loose sediments are compressed and hardened to form layer of rocks. These type of rocks are called sedimentary rocks.

(iii) Limestone is changed into marble.
Answer:
Limestone is changed into marble under the process of metamorphosis in which igneous or sedimentary rocks are exposed to heat and pressure.

Question 5.
For fun:
(i) What are the minerals most commonly used in the following objects?
Answer:

(ii) Identify some more objects made up of different minerals.
Answer: