Text Book Back Questions and Answers - Chapter 1 Interior of the Earth Term 1 7th Social Geography Guide Samacheer Kalvi Solutions - SaraNextGen [2024-2025]

Updated On May 15, 2024

By SaraNextGen

Chapter 1 - Interior of the Earth - Term 1 - 7th Social Geography Guide Samacheer Kalvi Solutions - Text Book Back Questions and Answers

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".
$\overline{\text { (a) Pacific }}$
(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

Answer:
1. iii
2. iv
3. $\mathrm{v}$
4. i
5. ii
V. Consider the following statement and $(\checkmark)$ Tick the appropriate answer.

Question 1.
Assertion (A): There structure of the earth may be compared to that of an Apple.
Reason $(\mathrm{R})$ : The interior of the earth consists of crust, mantle and core.
(a) A and R are correct and A explains R
(b) $\mathrm{A}$ and $\mathrm{R}$ are correct but $\mathrm{A}$ does not explain $\mathrm{R}$
(c) $\mathrm{A}$ is incorrect but $\mathrm{R}$ is correct
(d) Both $\mathrm{A}$ and $\mathrm{R}$ 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) $\mathrm{A}$ and $\mathrm{R}$ are correct but $\mathrm{A}$ does not explain $\mathrm{R}$
(c) $\mathrm{A}$ is incorrect but $\mathrm{R}$ is correct
(d) Both $\mathrm{A}$ and $\mathrm{R}$ 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.
1. The outer core, which is rich in iron, is in liquid state.
2. 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:
1. Shield volcano
2. Cinder-cone volcano
3. 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:

Question 2.
Shield volcano and composite volcano

Answer:

Question 3.
Active volcano and dormant volcano Answer:

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. Underground water system is naturally disturbed by such movements.
4. An earthquake which originates below or near the sea causes 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 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.
4. Mt. Stromboli in Mediterranean Sea, St.Helens in USA, Pinatubo in 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 this 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 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:
1. Volcanoes provide nutrients to the surrounding soil as volcanic ash contains minerals beneficial to plants.
2. Some plateaus and plains are formed due to volcanic eruption.
3. They cool off the earth removing heat from the interior.

Destructive effects:
1. They cause earth quakes, fast floods, mud slides and rock falls.
2. Dust and Ash that come out of volcanoes are very harmful to living things.

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

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
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 light house of Mediterranean sea.
6. Iceland, the most active volcanic area is located on the __________

Answer:
1. Volcanology
2. Volcanologists
3. Andaman sea
4. Stramboli
5. Mid-Atlantic ridge
III. Circle the odd one

1. 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

Answer:
1. $\mathrm{V}$
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 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 strato volcano.
(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: composite volcano is also called strato volcano.
VI. Answer in a word

Question 1.
What is the raduis 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 Indian ocean attack 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 as Endogenic forces and the forces that work on the surface of the earth are called as Exogenic forces.

Question 2.
What is 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 explosive eruption.

Question 3.
Mention any 2 causes of earthquake.
Answer:
1. The chief cause of earthquake is the sudden slipping of the portion of the earth's crust along fractures or faults.
2. Another cause of earthquake is volcanic activity.

Question 4.
What is 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 Mid continental belt
3. The Mid Atlantic belt
1. Circu $\mathrm{m}$ Belt: This is the volcanic zone of the convergent oceanic plate boundary. It includes the volcanoes of the eastern and western coastal areas of Pacific Ocean.
2. Mid continental belt:
1. 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.
2. The important volcanoes are Vesuvius, Stromboli, Etna, Kilimanjaro and Kenya.
3. Mid Atlantic Belt:
1. This belt represents the divergent boundary of plates located along the mid- Atlantic ridges. Volcanoes of this area are mainly of fissure eruption type.
2. 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 increases at the rate of $1^{\circ} \mathrm{c}$ for every 35 metres.
2. There is also great pressure. At a depth of about $15 \mathrm{~km}$ the pressure is about 5 tonnes per $\mathrm{cm}$ 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 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.