RBSE Solutions for Class 7 Social Science Geography Chapter 3 Our Changing Earth

Rajasthan Board RBSE Solutions for Class 7 Social Science Geography Chapter 3 Our Changing Earth Textbook Exercise Questions and Answers.

RBSE Class 7 Social Science Solutions Geography Chapter 3 Our Changing Earth

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

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Activity

Question 1. 
Read the ‘Earthquake A Case Study’ given in the form of headlines that appeared in the newspapers after the quake. Arrange the events in the right sequence of their happening. 
Answer:
Sequence: 1^4^5^2^6-4743

Question 2. 
the middle of the school day, where would you go for safety?
Answer: 
If a quake suddenly shook in the middle of the school day, then for safety weean go in open areas such as school ground, play ground etc.



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Question 3.
Find out the names of a few river of the World that form a delta?
Answer: 
Name of some rivers:

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

Question 1. 
Answer the following questions.

(i) Why do the plates move?
Answer: 
Plates move due to the movement of  molten magma found in the interior of the earth.

(ii) What are exogenic and endogenic forces?
Answer: 
Exogenic forces: The forces that work on the surface of the earth are called exogenic forces. E.g. river, wind, etc.
Endogenic forces: The forces which act in the interior of the earth are called endogenic forces. E.g. earthquake, volcano, etc.

(iii) What is erosion?
Answer: 
Erosion is wearing away of the landscape by different agents like running water, glacier, wind, ground water and sea waves.

(iv) How are flood plains formed?
Answer: 
At times the river overflows its banks which leads to the flooding in the neighbouring areas. As it floods, it deposits layers of fine soil and other material called sediments along its banks. This leads to the formation of flat fertile flood plains.

(v) What are sand dunes?
Answer: 
When the wind blows, it lifts and transports sand from one place to another. When it stops blowings, the sand falls and gets deposited in low hill-like structure. These structures are called sand dunes.

(vi) How are beaches formed?
Answer: 
Sea waves strike the coasts. They
erode the coasts and carry the eroded material in the form of silt and other material. When they withdraw, they deposit the silt and other material along the shore forming wide beaches.

(vii) What are ox-bow lakes?
Answer:
When the meander loop is cut off from the main river. It forms a cut-off lake called ox-bow lake.

Question 2. 
Tick the correct answer:
(i) Which is not an erosional feature of sea waves?
(a) Cliff 
(b) Beach
(c) Sea cave
Answer:
(b) Beach

(ii) The depositional feature of a glacier is:
(a) Flood plain 
(b) Beach
(c) Moraine
Answer:
(c) Moraine

(iii) Which is caused by the sudden movements of the earth ?
(a) Volcano 
(b) Folding
(c) Flood plain
Answer:
(a) Volcano 

(iv) Mushroom rocks are found in:
(a) Deserts 
(b) River valleys
(c) Glaciers
Answer:
(a) Deserts 

(v) Ox bow lakes are found in:
(a) Glaciers 
(b) River valleys
(c) Deserts
Answer:
(b) River valleys

Question 3.
Match the following: 

Answer:

Question 4. 
Give Reasons.
(i) Some rocks have a shape of a mushroom.
Answer:
In desert areas, rocks fall in the course of running dust storms. Winds usually erode the lower section of the rock more than the upper part. These kinds ofrocks have a narrower base and wide top and take up the shape of mushroom.

(ii) Flood plains are very fertile. 
Answer:
Flood plains are very fertile because of the following reasons:
(a) Flood plains formed due to the deposition of fine soil and other material are called sediments on the river banks.
(b) Due to spread of the new silt, the flood plains are fertile areas.

(iii) Sea caves are turned into stacks. 
Answer:
Sea caves are turned into stacks by the following process:
(a) Sea wave continuously strike at the rocks. Cracks develop. Over time they become larger and wider and hollow like caves are formed, called sea caves.
(b) As the cavities become bigger and bigger only the roof of the caves remain and forms sea arches.
(c) Further, erosion breaks the roof and only walls are left. These wall like features are called stacks.

(iv) Buildings collapse due to earth-quakes.
Answer:
When the earthquake strikes, the buildings are not capable of resisting the vibration of the earthquakes. Due to shallow foundation, sub-standard interior material and lack of adequate steel, the building collapse.