9th Social Science - Book Back Answers - Geography Unit 1

9th - Social Science - Book Back Answers - Geography Unit 1 - English Medium

Tamil Nadu Board 9th Standard Social Science - Geography Unit 1: Book Back Answers and Solutions

This post covers the book back answers and solutions for Unit 1 – Geography from the Tamil Nadu State Board 9th Standard Social Science textbook. These detailed answers have been carefully prepared by our expert teachers at KalviTips.com.

We have explained each answer in a simple, easy-to-understand format, highlighting important points step by step under the relevant subtopics. Students are advised to read and memorize these subtopics thoroughly. Once you understand the main concepts, you’ll be able to connect other related points with real-life examples and confidently present them in your tests and exams.

By going through this material, you’ll gain a strong understanding of Geography Unit 1 along with the corresponding book back questions and answers (PDF format).

Question Types Covered:

1 Mark Questions: Choose the correct answer, Fill in the blanks, Identify the correct statement, Match the following
2 Mark Questions: Answer briefly
3, 4, and 5 Mark Questions: Answer in detail

All answers are presented in a clear and student-friendly manner, focusing on key points to help you score full marks.

All the best, Class 9 students! Prepare well and aim for top scores. Thank you!

Topic: Unit 1. LITHOSPHERE I ENDOGENETIC PROCESSES

I. Choose the correct Answer

Question 1.
___________ is the rigid outer layer of the Earth.
(a) Core
(b) Mantle
(c) Crust
(d) Inner core
Answer Key:
(c) Crust

Question 2.
_________ layer is made up of liquid iron.
(a) Inner core
(b) Outer core
(c) Mantle
(d) Crust
Answer Key:
(b) Outer core

Question 3.
Magma is found in the ___________
(a) crust
(b) mantle
(c) core
(d) none of the above
Answer Key:
(b) mantle

Question 4.
Diastrophism is connected to ___________
(a) volcanism
(b) earthquakes
(c) tectonics
(d) fold/fault
Answer Key:
(d) fold/fault

Question 5.
The movement of tectonic plates is induced by ___________
(a) hydel
(b) thermal
(c) wave
(d) tidal
Answer Key:
(b) thermal

Question 6.
In the ancient period, Gondwanaland moved towards ___________
(a) north
(b) south
(c) east
(d) west
Answer Key:
(a) north

Question 7.
Many million years ago, India was a part of the supercontinent.
(a) Gondwana
(b) Laurasia
(c) Panthalasa
(d) Pangea.
Answer Key:
(a) Gondwana

Question 8.
The movement of plates that creates stress and tension in the rocks causing them to stretch and cracks result in ___________
(a) fold
(b) fault
(c) mountain
(d) earthquake
Answer Key:
(b) fault

Question 9.
___________ refers to a bowl-shaped depression found at the top of the volcano.
(a) Crater
(b) Vent
(c) Chamber
(d) Volcanic cone
Answer Key:
(a) Crater

Question 10.
The point of origin of an Earthquake is called the ___________
(a) epicentre
(b) focus
(c) seismic wave
(d) magnitude
Answer Key:
(b) focus

II. Match the Following

1. Endogenetic process       – (i) Seismograph
2. Mantle                             – (ii) Subduction Zone
3. Convergent boundaries – (iii) Volcanic
4. Earthquake                        – (iv) the Pacific Ocean
5. Composite volcano       – (v) SIMA

Answer Key:

1. Endogenetic process       – (iii) Volcanic
2. Mantle                          –   (v) SIMA
3. Convergent boundaries – (ii) Subduction Zone
4. Earthquake                      – (i) Seismograph
5. Composite volcano         – (iv) the Pacific Ocean

III. Consider the given statements

Question 1.
(i) Mt. Fuji is a dormant volcano
(ii) Mt. Kilimanjaro is a dormant volcano
(iii) Mt. Tanzania is a dormant volcano
Which of the statement(s) is are true
(a) (i) is true
(b) (ii) is true
(c) (iii) is true
(d) (i), (ii), (iii) are true
Answer Key:
(a) (i) is true

Question 2.
Statement: Magma gushes out when it finds vents.
Reason: Interior of the Earth contains compressed hot magma.
Which of the statement(s) is are true
(a) Statement & reason are true
(b) Statement is true, the reason is false
(c) Statement is false, the reason is true
(d) Statement & reason are false
Answer Key:
(a) Statement & reason are true

Question 3.
Statement I: Mountain ranges are formed by the collision of tectonic plates
Statement II: The movement of tectonic plates is due to the thermal energy from the mantle
(a) Statement I is false II is true
(b) Statement I and II are false
(c) Statement I is true II is false
(d) Statement I and II are true
Answer Key:
(d) Statement I and II are true

IV. Distinguish Between

Distinguish between:

1. CORE	CRUST
* Innermost layer of the earth. It is composed mainly of Nical and Iron. It is called NIFE.	* Outer layer of the earth. * It is composed mainly of Silica and Aluminium. * It is called SIAL.
2. EPICENTRE	HYPOCENTRE
* Epicentre is a point on the Earth's surface that lies directly above the focus. * The impact of the earthquake is felt the most at the epicenter.	* The point of origin of an Earthquake is called focus. * It generates a series of elastic waves
3. DIVERGENT BOUNDARY	CONVERGENT BOUNDARY
* The plates pull away from each other. * Magma pushes up from the mantle.	The plate moves towards each other. A plate sinks under another.
4. PRIMARY WAVES	SECONDARY WAVES
* These waves are the fastest of all the earthquake waves. * These waves passes through solids, liquids and gases.	These waves are slower than primary waves. These waves passes through only solids.
5. SHIELD VOLCANO	VOLCANIC DOME
* The lava of the volcanic flows out in all directions to create shield. * Ex.. Mauna Lao, Hawai.	* As the lava is rich in silica with intense viscosity, it deposits a circular mound formed. * Ex., Paricutin, Mexico.

V. Answer the following briefly

1. Write a brief note on the various spheres of the Earth.

Lithosphere - the solid outer part of the Earth.
Atmosphere - thin layer of gases that surrounds the Earth.
Hydrosphere - watery part of the Earth's surface.
Biosphere - the layer of Earth where life exists.

2. Mention the layers of the interior of the Earth.

The layers of the interior of the Earth is divided into three. They are the crust, the mantle and the core.

3. Define Plate tectonics.

The lithosphere is divided into a number of huge slabs of rocks called Tectonic plates.
These tectonic plates are divided into major and minor plates.

4. What is Tsunami?

Large seismically generated sea waves caused by Earthquakes, submarine explosions and landslides. It is called Tsunami.

5. What is a volcano? Mention its major components?

A volcano is a vent of the Earth crust through which hot magma erupt out to the surface from the Earth 's interior.

Components:

Magma chamber
Vents
Volcanic cone
Crater

6. What is an Earthquake and how it occurs?

Earthquakes are generally caused by the sudden vibrations in the Earth's crust.
The point of origin of an earthquake is called focus which generates a series of elastic waves.

7. What are seismic waves and mention its types?

Earthquake generates seismic waves.

Types:

Primary waves
Secondary waves
Surface waves.

8. Write about the Pacific Ring of Fire.

The Pacific Ring of Fire is an around the pacific ocean where many volcanoes are found.
The Ring of Fire is the most seismically and volcanically active zone in the world.

VI. Answer all the questions given under each caption

1. Describe the structure of the Earth.

The structure of the Earth 's interior is divided into three layers namely the crust, the mantles, and the core.

Crust:

Crust is the outer layer of the Earth where we live.
It is about 5 to 30 Kms.
It is the solid layer of the Earth.
The major elements of crust are Silica and Aluminium.

Mantle:

The interior part beneath the crust is called mantle.
It is about 2,900 Km thick.
The major elements of the mantle are Silica and Magnesium.

Core:

The core is the innermost part of the Earth.
It is the hottest layer.
The core is divided into solid inner core and the liquid outer core.
The major elements of core are Nical and Iron.

2. Write a note on the internal and external processes of Earth.

Internal processes:

The forces that act from the Earth 's interior towards the Earth 's surface are called Internal processes.

External processes:

The forces that act on the surface of the Earth are called External processes.
Running water, glacier, wind, waves etc., are some natural agents on the earth surface.

3. How are volcanoes classified based on the periodicity of their eruptions?

Based on the periodicity of eruptions volcanoes are classified into:

Active volcano
Dormant volcano
Extinct volcano

I. Active volcano:

These volcanoes are constantly eject volcanic lava, gases and fragmented materials. Ex., Mount St. Helens in the USA.

II. Dormant volcano:

These type of volcanoes do not show any sign of volcanic activity for a long period of time. Ex., Mt. Fugi, Japan.

III. Extinct volcano:

Some volcanoes permanently stops its volcanic activity. These are called dead or Extinct volcanoes. Ex., Mt. Kilimanjaro, Tanzania.

4. Explain the effects of volcanoes.

(i) Constructive effects:

Enrich the soil fertility that promotes agricultural activities.
These are the most attractive tourist spots of the world.
Most of the volcanic materials are used as building material.

(ii) Destructive effects:

Volcanic eruption causes Earthquake, fast floods, mud slide and rock fall.
The large amount of dust and ash makes breathing hard and irritable.
Volcanic eruption can alter the weather changes.