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

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Tamilnadu Samacheer Kalvi 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

Earth quake	(i)	Japanese term
Sima	(ii)	Africa
Pacific Ring of Fire	(iii)	Sudden movement
Tsunami	(iv)	Silica and magnesium
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 outermost layer of the earth.
Answer:
Crust

Question 2.
What is SIAL?
Answer:
The upper part of the crust

Question 3.
Name the movement of the Earth’s lithospheric plates.
Answer:
Tectonic movements

Question 4.
Give an example of an extinct volcano.
Answer:
Mt. Kilimanjaro and Mt. Kenya in Africa.

VII. Answer the following briefly:

Question 1.
What is the mantle?
Answer:
The middle layer of the earth is called the mantle. It is about 2900 m. thick. It is divided into two parts,

• The upper mantle
• The lower mantle

Question 2.
Write a note on the core of the earth.
Answer:

• The innermost layer of the earth is called the core. It is also known as the barysphere.
• The outer core and the inner core are the divisions of the core.

Question 3.
Define an Earthquake.
Answer:
A sudden movement of a portion of the earth’s crust which produces a shaking trembling is known as an earthquake.

Question 4.
What is Seismograph?
Answer:
The earthquake waves are recorded by an instrument is known as a 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 erupt from deep below the surface.

Question 6.
Name the three types of volcanoes based on shape.
Answer:
Volcanoes are classified according to their periodicity of eruptions and state of activity such as

1. Active Volcano
2. Dormant Volcano
3. Extinct Volcano

VIII. Give reason

Question 1.
No one has been able to take samples from the interior of the earth
Answer:

• The interior of the earth the central core has a very high temperature and pressure.
• So no one cannot be able to take samples from the interior of the earth.

Question 2.
The Continent crust is less dense than the oceanic crust
Answer:

• The continental crust is less dense than the oceanic crust because it is made of both light and dense rock types.
• The oceanic crust is composed of dense rocks.

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 the quiet eruption of lava with 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 the USA

Question 3.
Active volcano and a 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 the USA, Pinatubo in the 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:

1. Earthquakes may cause changes in the earth’s surface. Vibrations often set landslides in mountainous regions.
2. A greater danger in an earthquake is the falling of buildings.
3. Fire is another great danger. The underground water system is naturally disturbed by such movements.
4. An earthquake which originates below or near the sea causes a great disturbance in the water.
5. 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:

1. Volcanoes are also grouped according to their periodicity of eruptions such as active, dormant, and extinct.
2. These names refer to the state of activity rather than the types of volcanoes
3. Active Volcanoes 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.
4. Mt. Stromboli in the Mediterranean Sea, St.Helens in the USA, Pinatubo in the Philippines.
5. 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
6. Vesuvius mountain of Italy, Mt Fujiyama in Japan, Mt. Krakatoa of Indonesia are famous examples of these types.
7. 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 anyone.
Answer:
There are three major zones of Volcanic activities in the world. They are

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

The Circum – Pacific belt

• Circum Belt is the convergent oceanic plate boundary.
• It includes the volcanoes of the eastern and western coastal areas of the Pacific Ocean.
• This zone is termed the Pacific Ring of fire.
• This Zone includes two – thirds of the world’s Volcanoes.

XI. HOTs

Question 1.
The earth’s interior is very hot. Why?
Answer:

• The inner core of the earth consists of Nickel and Ferrous.
• It has a very high temperature and pressure.
• So the earth’s interior is very hot.

Question 2.
Are Volcanoes Destructive (or) Constructive?
Answer:

• Volcanes have both destructive and constructive forces.
• They are constructive because cooled lava is good for the soil. It is rich in minerals.
• Volcanoes are destructive because the lava can start fires and brunt things like houses, trees, and people.

Question 3.
How do volcanoes make on Island?
Answer:

• In the form of a Volcano, where magma rises upward until it erupts on the seafloor is called a “hotspot”.
• Thus Volcanoes makes on Island.
• Ex: Hawaii Islands.

XII. Activity

Question 1.
On an outline map of the world, mark the Pacific Ring of Fire
Answer:

Question 2.
Lable the parts of a 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 earthquake 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

II. Fill in the Blanks

1. The scientific study of volcanoes is called ________
2. People who study volcanoes are called ________
3. Lava flow is affected by ________
4. Barren Island is situated in the ________
5. ________ is known as the lighthouse of the Mediterranean sea.
6. Iceland, the most active volcanic area is located on the ________

Answer:

1. Volcanology
2. Volcanologists
3. Andaman sea
4. Stromboli
5. Mid-Atlantic ridge

III. Circle the odd one

1. An active volcano, Dormant volcano, Extinct Volcano, Shield volcano
2. Mt. Popa, Mt. Fujiyama, Mt. Kilimanjaro, Mt. Kenya.
3. Vesuvius, Stromboli, St.Helena, Etna.

Answer:

1. Shield volcano
2. Mt. Fujiyama
3. St.Helena

IV. Match the following

Earth	i	Trembling
Core	ii	Andaman
Earthquake	iii	Lighthouse
Barren island	iv	Barysphere
Stramboli	v	Blue planet

Answer:

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

V. Consider the following statement and Tick the appropriate answer:

Question 1.
Statement 1: When magma rises slowly to the surface and spreads over a vast area. It is known as a fissure eruption
Statement 2: The viscosity of lava is determined by the amount of silica and water in magma.
(a) 1 is true, 2 is wrong.
(b) 1 is wrong, 2 is true.
(c) Both the statements are true.
(d) Both the statements are wrong.
Answer:
(c) Both the statements are true.

Question 2.
Statement 1: Many volcanoes of Mexico and Central America are cinder-cone volcanoes.
Statement 2: Shield volcano is also called stratovolcano.
(a) 1 is true, 2 is wrong.
(b) 1 is wrong, 2 is true.
(c) Both the statements are true.
(d) Both the statements are wrong.
Answer:
(a) 1 is true, 2 is wrong
Hints: a composite volcano is also called a stratovolcano.

VI. Answer in a word

Question 1.
What is the radius of the earth?
Answer:
6371

Question 2.
Name the point where the vibrations originate in an earthquake.
Answer:
Focus.

Question 3.
What is the point of the earth’s surface directly above the focus called?
Answer:
Epicentre.

Question 4.
Tsunami when did the Indian ocean attack the coastal area of Indonesia, India Srilanka, and Thailand.
Answer:
26th December 2004.

VII. Answer the following in Brief.

Question 1.
What are endogenic and exogenic forces?
Answer:
The forces which act in the interior of the earth are called Endogenic forces and the forces that work on the surface of the earth are called Exogenic forces.

Question 2.
What is an explosive eruption?
Answer:
If the magma rises quickly to the surface, lava is thrown high into the atmosphere. Besides lava, ash, steam, gases, and pieces of rocks are also thrown out. This type of eruption is known as an explosive eruption.

Question 3.
Mention any 2 causes of earthquake.
Answer:

1. The chief cause of earthquakes is the sudden slipping of the portion of the earth’s crust along with fractures or faults.
2. Another cause of earthquakes is volcanic activity.

Question 4.
What is the asthenosphere?
Answer:
The asthenosphere is the part of the mantle that flows and moves the plates of the earth.

VIII. Answer the following questions in detail.

Question 1.
Explain three major zones of volcanic activities in the world.
Answer:
There are three major zones of volcanic activities in the world. They are:

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

1. Circu m Belt: This is the volcanic zone of the convergent oceanic plate boundary. It includes the volcanoes of the eastern and western coastal areas of the Pacific Ocean.

2. Mid continental belt:

• This is the volcanic zone of convergent continental plate boundaries that includes the volcanoes of Alpine mountain chains, the Mediterranean Sea and the fault zone of eastern Africa.
• The important volcanoes are Vesuvius, Stromboli, Etna, Kilimanjaro, and Kenya.

3. Mid Atlantic Belt:

• This belt represents the divergent boundary of plates located along the mid-Atlantic ridges. Volcanoes of this area are mainly of fissure eruption type.
• St. Helena and Azores Island are other examples.

Question 2.
What are the causes of volcanic activity?
Answer:
Causes of Volcanic Activity

1. The temperature increases as the depth increase at the rate of 1°c for every 35 meters.
2. There is also great pressure. At a depth of about 15 km, the pressure is about 5 tonnes per cm of rock.
3. Under these circumstances, the interior of the earth is in a semi-molten state called magma.
4. The magma, under great pressure, has the capacity to dissolve a great volume of gas; some gases are also combustible.
5. This makes volcanic material burst forth through the weak spots in the earth’s crust.