Here we are providing Class 7 Geography Chapter 3 Extra Questions and Answers Our Changing Earth was designed by subject expert teachers. https://ncertmcq.com/extra-questions-for-class-7-social-science/
Our Changing Earth Class 7 Extra Questions Geography Chapter 3
Class 7 Geography Chapter 3 Extra Questions And Answers Question 1.
What are lithospheric plates?
Answer:
The lithosphere is broken into a number of large and small, rigid and irregularly shaped plates called lithospheric plates.
Class 7 Geography Chapter 3 Extra Questions Question 2.
Lithospheric plates move a few millimetres each year. Why?
Answer:
The lithospheric plates move because of the movement of molten magma in a circular manner inside the earth.
Our Changing Earth Class 7 Extra Questions Question 3.
Why are changes observed on the surface of the earth?
Answer:
Changes are observed on the earth’s surface due to the movement of lithospheric plates.
Our Changing Earth Class 7 Worksheet With Answers Question 4.
Name the forces which cause earth’s movements.
Answer:
Following are the two forces which cause earth’s movement-
- Endogenic forces,
- Exogenic forces.
Our Changing Earth Extra Questions Question 5.
Define endogenic forces.
Answer:
The forces that act below (i.e., in the interior of) the earth’s surface are called endogenic forces.
Ncert Class 7 Geography Chapter 3 Extra Questions Question 6.
Define exogenic forces.
Answer:
The forces that work on the surface of the earth are called exogenic forces.
Chapter 3 Geography Class 7 Extra Questions Question 7.
Why are earthquakes and volcanoes caused?
Answer:
Earthquakes and volcanoes are caused when endogenic forces produce sudden movements.
Geography Class 7 Chapter 3 Extra Questions Question 8.
What is a volcano?
Answer:
A volcano is a vent (opening) in the earth’s crust through which molten materials erupt suddenly.
Class 7 Geography Ch 3 Extra Questions Question 9.
What are earthquakes?
Answer:
The movement of lithospheric plates causes vibrations in the earth’s surface. These vibrations can travel all round the earth and are called earthquakes.
Our Changing Earth Class 7 Worksheet With Answers Pdf Question 10.
Define the terms ‘focus’ and ‘epicentre’.
Answer:
- The place in the earth’s crust where the movement of an earthquake starts is called the focus.
- The place on the earth’s surface above the focus is called the epicentre.
Extra Questions For Class 7 Geography Chapter 3 Question 11.
How and in which direction do the vibrations move during an earthquake?
Answer:
During an earthquake, vibrations move as waves outwards from the epicentre.
Geography Chapter 3 Class 7 Extra Questions Question 12.
Place A is situated 20 km away from the epicentre and Replace B is at a distance of 80 km from the epicentre. Which one will receive more damage and why?
Answer:
Place A will receive more damage because greatest damage is usually closest to the epicentre and the strength of the waves decreases as they travel away from the epicentre.
Our Changing Earth Class 7 Questions And Answers Question 13.
What are the earthquake waves called?
Answer:
Seismic waves.
Our Changing Earth Class 7 Extra Questions And Answers Question 14.
What happens when lithospheric plates move slowly?
Answer:
The slow movement of lithospheric plates causes dislocation on the earth’s crust like faulting and folding.
Class 7 Chapter 3 Geography Extra Question Answer Question 15.
Which type of force is responsible for formation of mountains?
Answer:
Endogenic force.
Question 16.
Which machine is used to measure an earthquake?
Answer:
Seismograph.
Question 17.
Name the instrument used to measure the magnitude of an earthquake?
Answer:
Richter scale.
Question 18.
Which safe spots will you suggest to stay in during an earthquake?
Answer:
- Under a kitchen counter, table or desk.
- Against an inside corner or wall.
Question 19.
Mention some animal behaviour that helps the local people to predict an earthquake.
Answer:
Animals like fish in ponds get agitated or snakes come to the surface before an earthquake reaches the earth’s surface.
Question 20.
Name any three actions of sudden endogenic force.
Answer:
- It causes earthquakes.
- It causes eruption of volcano.
- It causes landslides.
Question 21.
Give three examples of works done by exogenic force.
Answer:
- It does erosional work.
- It is responsible for the flow of water in the rivers.
- It causes winds and sea waves.
Question 22.
What types of wave are formed during an earthquake?
Answer:
Following three types of wave are formed during an earthquake-
- P waves or longitudinal waves.
- S waves or transverse waves.
- L waves or surface waves.
Question 23.
What do you mean by ‘earthquake preparedness?
Answer:
Since it is impossible to predict the time of occurrence of an earthquake, so to minimise its effects, some measures are taken as precautionary measures, e.g., selection of a safe site, awareness among the people, etc. These measures constitute earthquake preparedness.
Question 24.
List some things or place to stay away from during an earthquake.
Answer:
- Fireplace.
- Areas around chimney.
- Buildings and electric poles.
- Windows that shelter, including mirrors and picture frame.
Question 25.
Name the process responsible for the creation of different landforms on the earth’s surface.
Answer:
Weathering and erosion.
Question 26.
Define weathering.
Answer:
The process of breaking up of the rocks on the earth’s surface is called weathering.
Question 27.
Define erosion.
Answer:
The process of wearing away of the landscape by different agents like water, wind and ice is called erosion.
Question 28.
Name any two agents responsible for transport and deposition of eroded materials.
Answer:
Water, ice and wind.
Question 29.
Name the features formed by a river.
Answer:
Following are the features formed by a river :
- Waterfall
- Meanders
- Ox-bow lakes
- Levees
- Floodplains
- Delta
Question 30.
Define the following terms :
(a) Ox-bow lake
(b) Levees
(c) Meanders
Answer:
(a) Ox-bow lake – When a river enters the plain, it forms a large bend which is cut-off from the mainstream in due course of time. The cut-off stream takes the form of a lake called ox-bow lake.
(b) Levees – During flood, a river deposits sediments along its banks. Thus the banks rise. The raised banks are called levees.
(c) Meanders – When a river enters the plain, it twists and turns forming large bends. These bends are called meanders.
Question 31.
When are the following features of river formed?
(a) Waterfall
(b) Floodplains
(c) Delta
Answer:
(a) Waterfall – When the river tumbles at a steep angle over very hard rocks or down a steep valley side, it forms a waterfall.
(b) Floodplains – When a river outflows its banks, it causes floods in the neighbouring areas. The flood water takes away fine soil and other materials and deposits them in layers along the banks. This deposition leads to the formation of a flat fertile land called floodplain.
(c) Delta – When a river reaches the sea, it breaks into many streams and also its speed slows down. These streams are called distributaries having their own mouths. The sediment from all the mouths form a delta.
Question 32.
How are coastal landforms formed?
Answer:
Coastal landforms are formed due to erosional and depositional works of the sea waves.
Question 33.
Name the features made by sea waves.
Answer:
Following are the features made by sea waves :
- Sea caves
- Sea arches
- Sea cliffs
- Stacks
- Sea beaches.
Question 34.
How are sea caves formed?
Answer:
Strong sea waves continuously strike the nearby rocks and cause them to crack. In course of time, these cracks in the rocks widen and become larger giving rise to hollow-like caves. These caves are called sea caves.
Question 35.
When are sea arches formed?
Answer:
When the hollows, i.e., sea caves become bigger and bigger, only their roof remains. These structures are called sea arches.
Question 36.
What do you mean by ‘stacks’?
Answer:
When the roof of a sea cave is eroded by continuous erosion, only walls are left. These wall-like features are called stacks.
Question 37.
Define sea cliff.
Answer:
The steep rocky coast rising almost vertically above seawater is called sea cliff.
Question 38.
When are beaches formed?
Answer:
Beaches are formed when sea waves deposit sediments along the seashores.
Question 39.
What are glaciers? How do they erode the landscape?
Answer:
- Glaciers are the rivers of ice.
- They erode the landscape by bulldozing soil and stones to expose the solid rocks below.
Question 40.
How do glaciers form mountain lakes?
Answer:
Glaciers create deep hollow in the solid rocks. When ice melts, the hollow is filled up with water giving rise to mountain lakes.
Question 41.
How are glacial moraines formed?
Answer:
The glaciers carry materials like big and small rocks, sand and silt and deposit them at a place. These deposits form glacial moraines.
Question 42.
List a few features formed by wind.
Answer:
- It forms mushroom rock.
- It forms loess.
- It forms sand dunes.
Question 43.
Where are mushroom rocks found? How are they formed?
Answer:
- The mushroom-shaped rocks called mushroom rocks are found in deserts.
- When winds erode the lower part of the rock more than the upper part, the rock looks like a mushroom with a narrower base and a wider top. This is called a mushroom rock.
Question 44.
Where do you find sand dunes? How are they formed?
Answer:
- Sand dunes are found in deserts.
- Winds lift and carry sand from one place to another in deserts. When winds stop blowing, sand falls and gets deposited in low hill-like structures called sand dunes.
Question 45.
What are loess? Where are large deposits of loess found?
Answer:
- Light and fine grains of sand can be carried by winds over longer distances. When such sand is deposited in wider areas, they are called loess.
- Large deposits of loess is found in China.
Multiple Choice Questions (MCQs)
1. Which one of the following terms is used for the plates of lithosphere?
(a) Focus
(b) Lithospheric plates
(c) Epicentre
(d) Eurasian plate
Answer:
(b) Lithospheric plates.
2. Which one of the following forces is found in the interior of the earth?
(a) Endogenic force
(b) Exogenic force
(c) Gravitational force
(d) Sudden force.
Answer:
(a) Endogenic force.
3. Which one of the following forces is active on the surface of the earth?
(a) Endogenic force
(b) Diastrophic force
(c) Sudden force
(d) Exogenic force
Answer:
(d) Exogenic force.
4. Which one of the following is a vent in the earth’s crust through which molten material erupts suddenly?
(a) Rocks
(b) Valley
(c) Volcano
(d) Oceans
Answer:
(c) Volcano.
5. Which one of the following is false about the earthquakes?
(а) The molten lava comes out through a vent.
(b) Sudden vibrations of the earth’s surface are called earthquakes.
(c) Focus is the place in the earth’s crust where the movement of earthquake waves start.
(d) Epicentre is the place on the surface above the focus.
Answer:
(а) The molten lava comes out through a vent.
6. Which one of the following places is situated above the focus of the earthquake?
(a) Vent
(b) Epicentre
(c) Crater
(d) Magma chamber
Answer:
(b) Epicentre.
7. Which one of the following is different from the other three, with reference to the types of earthquake waves?
(a) Longitudinal (P) waves
(b) Transverse (S) waves’
(c) Surface (L) waves
(d) Sea waves.
Answer:
(d) Sea waves.
8. Which one of the following is different from the other three, with reference to the sudden forces?
(a) Earthquakes
(b) Volcano
(c) Building mountains
(d) Landslides.
Answer:
(c) Building mountains.
9. Which one of the following is caused by the exogenic forces?
(a) Erosion and deposition
(b) Earthquakes
(c) Building mountains
(d) Landslides.
Answer:
(a) Erosion and deposition.
10. Which one of the following instruments is used to measure an earthquake?
(a) Barometer
(b) Seismograph
(c) Richter scale
(d) Hygrometer.
Answer:
(b) Seismograph.
11. Which one of the following scales is used to measure the magnitude of the earthquake?
(a) Metre scale
(b) Farhenheit scale
(c) Richter scale
(d) Vernier scale.
Answer:
(c) Richter scale.
12. Which one of the following statements is true about weathering?
(а) Wearing away of the landscapes by different agents.
(b) A sudden vibration in the earth’s crust.
(c) Forces that work beneath the earth surface.
(d) Breaking up of the rocks on the earth’s surface.
Answer:
(d) Breaking up of the rocks on the earth’s surface.
13. Which one of the following processes create different landforms on the earth’s surface?
(a) Volcanoes and landslides
(b) Landslides and earthquakes
(c) Earthquake and soil creeping
(d) Erosion and deposition.
Answer:
(d) Erosion and deposition.
14. Which one of the following is the highest waterfall of the world?
(a) Angel
(b) Jog
(c) Victoria
(d) Niagara.
Answer:
(a) Angel.
15. Which one of the following landscapes is formed by the erosional work of the river?
(a) Flood plains
(b) Ox-bow lake
(c) Waterfall
(d) Delta.
Answer:
(c) Waterfall.
16. Which one of the following is formed by the deposition of sediments carried by rivers?
(a) Coastal plains
(b) Flood plains
(c) Natural levees
(d) Meander.
Answer:
(b) Flood plains.
17. Which one of the following is not associated with the work of sea waves?
(a) Sea orches
(b) Stacks
(c) Seacliff
(d) Sand dunes.
Answer:
(d) Sand dunes.
18. Seacliff is found at which one of the following places?
(a) Sea coast
(b) Flood plains
(c) Deserts
(d) Glaciers
Answer:
(a) Sea coast.
19. Which one of the following is false about the glaciers?
(a) Glaciers are the river of ice.
(b) Glaciers form sea caves.
(c) Glaciers form glacial moraines.
(d) Glaciers carve out deep hollows.
Answer:
(b) Glaciers form sea caves.
20. Which one of the following features is formed due to the depositional work of glaciers?
(a) V-shaped valley
(b) George
(c) Glacial morains
(d) Stacks.
Answer:
(c) Glacial morains.
21. Which one of the following is an active agent of erosion and deposition in the desert areas?
(a) Water
(b) Glaciers
(c) Sea waves
(d) Wind.
Answer:
(d) Wind.
22. Which one of the following rocks is associated with the work of wind in the desert areas?
(a) Mushroom rocks
(b) Sedimentary rocks
(c) Igneous rocks
(d) Metamorphic rocks.
Answer:
(a) Mushroom rocks.
23. Which one of the following terms is used for the hill like structures of deserts?
(a) Loess
(b) Sand dunes
(c) Mushroom rock
(d) Arches.
Answer:
(b) Sand dunes.
24. Sand deposition in large areas of deserts is termed as :
(a) Mushroom rocks
(b) Sand dunes
(c) Loess
(d) Stack.
Answer:
(c) Loess.
25. At which one of the following places the large deposits of loess is found?
(a) China
(b) India
(c) Saudi Arab
(d) Iraq
Answer:
(a) China.