Samacheer Guide 7th Social Science Geography Solutions Term 1 Chapter 1 Interior Of The Earth

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Tamilnadu Samacheer Guide 7th Social Science Geography Solutions Term 1 Chapter 1 Interior Of The Earth

Samacheer Kalvi 7th Social Science Interior Of The Earth Textual Evaluation

I. Choose the correct answer:

Question 1.

Nife is made up of _______

(a) Nickel and ferrous

(b) Silica and aluminum

(c) Silica and magnesium

(d) Iron and magnesium

Answer:

(a) Nickel and ferrous

Question 2.

Earthquake and volcanic eruption occur near the edges of _______

(a) Mountain

(b) Plains

(c) Plates

(d) Plateaus

Answer:

(a) Mountain

Question 3.

The magnitude of an earthquake is measured by _______

(a) Seismograph

(b) Richter scale

(c) Ammeter

(d) Rotameter

Answer:

(b) Richter scale

Question 4.

The narrow pipe through which magma flow out is called a _______

(a) Vent

(b) Crater

(c) Focus

(d) Caldera

Answer:

(a) Vent

Question 5.

Lava cones are _______

(a) mountains of accumulation

(b) mountains of deformation

(c) relicit mountains

(d) fold mountains

Answer:

(a) mountains of accumulation

Question 6.

The top of the cone of a volcanic mountain has a depression known as the _______

(a) crater

(b) lopith

(c) caldera

(d) sill

Answer:

(a) crater

Question 7.

_______ belt is known as the “Ring of Fire”.

(a) Pacific

(b) Atlantic

(c) Arctic

(d) Antarctic

Answer:

(a) Pacific

II. Fill in the Blanks

Question 1.

• The core is separated from the mantle by a boundary called _______

Answer:

Weichart – Gutenberg discontinuity

Question 2.

• The earthquake waves are recorded by an instrument known as _______

Answer:

seismograph

Question 3.

• Magma rises to the surface and spreads over a vast area is known as _______

Answer:

fissure eruption

Question 4.

• An example for active volcano _______

Answer:

St. Helens USA

Question 5.

• Seismology is the study of _______

Answer:

earthquake

III. Circle the odd one

Question 1.

• crust, magma, core, mantle

Answer:

magma

Question 2.

• focus, epicenter, vent, seismic waves

Answer:

vent

Question 3.

• Uttar Kashi, Chamoli, Koyna, Krakatoa

Answer:

Krakatoa

Question 4.

• lava, caldera, silica, crater

Answer:

silica

Question 5.

• Stromboli, Helens, Hawaii, Fujiyama

Answer:

Fujiyama

IV. Match the following

1. Earth quake (i)  Japanese term
2. Sima (ii) Africa
3. Pacific Ring of Fire (iii) Sudden movement
4. Tsunami                  (iv)   Silica and magnesium
5. Mt. Kenya        (v)    World volcanoes

Answer:

1. iii
2. iv
3. v
4. i
5. ii

V. Consider the following statement and (✓) Tick the appropriate answer.

Question 1.

Assertion (A): There structure of the earth may be compared to that of an Apple.

Reason (R) : The interior of the earth consists of crust, mantle and core.

(a) A and R are correct and A explains R

(b) A and R are correct but A does not explain R

(c) A is incorrect but R is correct

(d) Both A and R are incorrect

Answer:

(a) A and R are correct and A explatns R

Question 2.

Assertion (A): The Pacific Ocean includes two thirds of the world’s volcanoes.

Reason (R) : The boundary along the Eastern and Western coast areas of the Pacific

Ocean is known as the Pacific Ring of Fire.

(a) A and R are correct and A explains R

(b) A and R are correct but A does not explain R

(c) A is incorrect but R is correct

(d) Both A and R are incorrect

Answer:

(a) A and R are correct and A explains

VI. Answer in a word

Question 1.

Name the outer most layer of the earth.

Answer:

Crust

Question 2.

What is SIAL?

Answer:

Silica and Alumina.

Question 3.

Name the movement of the Earth’s lithospheric plates.

Answer:

Tectonic movements

Question 4.

Give an example of extinct volcano.

Answer:

Mt. Popa of Myanmar

VII. Answer the following briefly:

Question 1.

What is mantle?

Answer:

• The layer of the earth beneath the crust is called the mantle. It is separated from the crust by a boundary called Mohorovicic discontinuity.

Question 2.

Write note on the core of the earth.

Answer:

• The innermost layer of the earth is called the core. It is also known as barysphere. It is separated from the mantle by a boundary called Weichart-Gutenberg discontinuity. The core is also divided into two parts.
• The outer core, which is rich in iron, is in liquid state.
• The inner core, composed of Nickel and Ferrous (Nife), is solid in state.

Question 3.

Define Earthquake.

Answer:

• A sudden movement of a portion of the earth’s crust which produces a shaking or trembling is known as an earthquake.

Question 4.

What is a Seismograph?

Answer:

• The earthquake waves are recorded by an instrument known as seismograph.

Question 5.

What is a volcano?

Answer:

• A volcano is a vent or an opening in the earth’s crust through which hot magma erupts from deep below the surface. The opening is usually circular in form.

Question 6.

Name the three types of volcanoes based on shape.

Answer:

• On the basis of shape, there are three types of volcanoes. They are:
• Shield volcano
• Cinder-cone volcano
• Composite volcano

VIII. Give reason

Question 1.

No one has been able to take samples from the interior of the earth

Answer:

• The innermost layer of the earth is called the core. The central core has very high temperature and pressure. So no one has been able to take samples from the interior of the earth.

Question 2.

The Continent crust is less dense than the oceanic crust

Answer:

• Despite greater thickness, the continental crust is less dense than the oceanic crust because it is made of both light and dense rock typps.

IX. Distinguish between

Question 1.

SIAL and SIMA

Answer:

S.No	‘SIAL	‘SIMA
1	The upper part of the earth’s crust	The lower part of the crust.
2	Has granite rocks and forms continents.	Continuous zone of denser basaltic rocks forming ocean floor.
3	Has silica and Alumina referred to as SIAL	Has silica and Magnesium called SIMA.

Question 2.

Shield volcano and composite volcano

Answer:

S.No	‘Shield volcano	‘Composite volcano
1	A shield volcano is formed by quiet eruption of lava with a low silica content.	Composite volcanoes are made of alternate layers of lava, cinder and ash..
2	Eg. Volcanoes of the Hawaii islands.	Eg. St. Helens in USA

Question 3.

Active volcano and dormant volcano

Answer:

S.No	Active volcano	‘Dormant volcano
1	Active Volcanoes erupt frequently.	Dormant Volcanoes have shown no sign of activity for many years but may become active at any time.
2	Eg. St.Helens in USA, Pinatubo in Philippines	Eg. Mt Fujiyama in Japan, Mt. Krakatoa of Indonesia

X. Answer the following questions in detail

Question 1.

Write about the effects of an earthquake.

Answer:

• Earthquakes may cause changes in the earth’s surface. Vibrations often set landslides in mountainous regions.
• A greater danger in an earthquake is the falling of buildings.
• Fire is another great danger. Underground water system is naturally disturbed by such movements.
• An earthquake which originates below or near the sea causes great disturbance in the water.
• Tsunami, a Japanese term, is the name given to the huge wave caused in the sea by an earthquake.

Question 2.

Describe the classification of volcanoes based on the eruptions.

Answer:

• Volcanoes are also grouped according to their periodicity of eruptions such as active, dormant and extinct.
• These names refer to the state of activity rather than the types of volcanoes
• Active Valcanoes that erupt frequently are called active volcanoes. Most of the active volcanoes lie in the Pacific Ring of Fire belt which lies along the Pacific coast.
• Mt. Stromboli in Mediterranean Sea, St.Helens in USA, Pinatubo in Philippines.
• Dormant volcanoes have shown no sign of activity for many years but they may become active at any time. It is also called Sleeping Volcano
• Vesuvius mountain of Italy, Mt Fujiyama in Japan, Mt. Krakatoa of Indonesia are famous examples of this types.
• Extinct The top of extinct volcanic mountains have been eroded. Mt Popa of Myanmar and Mt. Kilimanjaro and Mt. Kenya of Africa are examples of extinct volcanoes.

Question 3.

Name the major zones of volcanic activity and explain any one.

Answer:

There are three major zones of volcanic activities in the world. They are:

1. The Circum – Pacific belt
2. The Mid continental belt
3. The Mid Atlantic belt

Circum Beit

• This is the volcanic zone of the convergent oceanic plate boundary. It includes the volcanoes of the eastern and western coastal areas of Pacific Ocean. This zone is popularly termed as the Pacific Ring of Fire which has been estimated to include two-thirds of the world’s volcanoes

XI. HOTs

Question 1.

The earth’s interior is very hot. Why?

Answer:

1. The inner most layer of the earth, called the core has two parts, the outer core and the inner core.
2. The outer core is rich in iron and is in liquid state.
3. The inner core is made of Nickel and Ferrous which is in solid state.
4. The central core has very high temperature and pressure

Question 2.

Are Volcanoes Destructive (or) Constructive?

Answer:

• Volcanoes are constructive and Destructive.

Constructive effects:

• Volcanoes provide nutrients to the surrounding soil as volcanic ash contains minerals beneficial to plants.
• Some plateaus and plains are formed due to volcanic eruption.
• They cool off the earth removing heat from the interior.

Destructive effects:

• They cause earth quakes, fast floods, mud slides and rock falls.
• Dust and Ash that come out of volcanoes are very harmful to living things.
• Samacheer Kalvi 7th Social Science Geography Solutions Term 1 Chapter 1 Interior Of The Earth

Question 3.

How does volcaone make on Island?

Answer:

• Some volcanoes are found under oceans . If an underwater volcano keeps erupting, it can rise above the ocean’s surface and thus as Island is formed.

XII. Activity

Question 1.

On an outline map of the world, mark the Pacific Ring of Fire

Answer:

Question 2.

Lable the parts of volcano.

Answer:

Question 3.

Prepare an album on earthquake and volcanoes

Answer:

• Activity to be done by the students themselves

Puzzle

Answer:

Across

1. Point of origin of Earthquake

4. Molten rock under the surface

5. Waves triggered by deep ocean earthquake

6. Inner layer of the Earth

Down

2. Extinct volcano in Europe

3. Top layer of the Earth

4. Middle layer of Earth

Samacheer Kalvi 7th Social Science Interior Of The Earth Additional Questions

I. Choose the correct answer:

Question 1.

An earth quake of magnitude ________ scale can cause damage from things falling.

(a) 3.0

(b) 4.0

(c) 5.0

(d) 2.0

Answer:

(c) 5.0

Question 2.

In India, the Himalayan region and the ________ valley are prone to earthquakes.

(a) Ganga – Brahmaputra

(b) Yamuna

(c) Sind

(d) Sutle

Answer:

(a) Ganga-Brahmaputra

Question 3.

If the crater of a volcano is of great size and is shaped like a basin, it is called a ________

(a) Vent

(b) Crater

(c) Caldera

(d) Magma

Answer:

(c) Caldera

Question 4.

Volcanoes made of cinder and ash and which have sleep slopes are ________ volcanoes.

(a) Shield

(b) Cinder-cone

(c) Composite

(d) Dormant

Answer:

(c) Composite