Class 7 Geography chapter 3 questions and answers
Here are the NCERT book questions and answers from Class 7 Geography Chapter 3: "Our Changing Earth" (as per textbook exercises):
📘 Chapter 3 – Our Changing Earth
NCERT Textbook Questions and Answers
🔴 Q1. Answer the following questions briefly.
(a) Why do the plates move?
Ans: The movement of molten magma inside the Earth creates convection currents, which cause the plates to move.
(b) What are exogenic and endogenic forces?
Ans:
Exogenic forces are the external forces that work on the Earth's surface (e.g., erosion, weathering).
Endogenic forces are the internal forces that act in the interior of the Earth (e.g., earthquake, volcano).
(c) What is erosion?
Ans: Erosion is the wearing away of the land surface by agents like wind, water, and ice.
(d) How are flood plains formed?
Ans: When rivers overflow their banks during floods, they deposit layers of fine soil and sediments on the riverbanks. This leads to the formation of flat, fertile flood plains.
(e) What are sand dunes?
Ans: Sand dunes are mounds or ridges of sand formed in deserts when wind blows sand and deposits it in one place.
(f) How are ox-bow lakes formed?
Ans: Ox-bow lakes are formed when a meandering river forms a loop, which gets cut off from the main river, leaving behind a crescent-shaped water body.
🔵 Q2. Tick the correct answer.
Which is not an erosional feature of sea waves?
(b) Beach ✅The depositional feature of a glacier is:
(c) Moraine ✅Which is caused by the sudden movements of the Earth?
(a) Volcano ✅Mushroom rocks are found in:
(c) Deserts ✅Ox-bow lakes are found in:
(a) River valleys ✅
🟠 Q3. Match the following.
| Column A | Column B |
|---|---|
| Glacier | River of ice |
| Meanders | Loop-like bend of river |
| Beach | Sea shore |
| Sand dunes | Deserts |
| Waterfall | Hard bedrock |
✅ Answers:
Glacier → River of ice
Meanders → Loop-like bend of river
Beach → Sea shore
Sand dunes → Deserts
Waterfall → Hard bedrock
🟢 Q4. Give reasons.
(i) Some rocks have a shape of a mushroom.
Ans: In deserts, wind erodes the lower part of rocks more than the upper part. This gives them a mushroom-like shape. These are called mushroom rocks.
(ii) Flood plains are very fertile.
Ans: Flood plains are made of fine soil and sediments deposited by rivers during floods, which makes them very fertile.
(iii) Sea caves are turned into stacks.
Ans: Sea waves erode the base of cliffs to form sea caves. With continuous erosion, the roof collapses, and only the wall-like structures remain, called stacks.
(iv) Buildings collapse due to earthquakes.
Ans: Earthquakes cause vibrations that shake the ground violently. Weak structures or buildings collapse due to these tremors.
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