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.
_______
belt is known as the “Ring of Fire”.
(a)
Pacific
(b)
Atlantic
(c)
Arctic
(d)
Antarctic
Answer:
(a)
Pacific
II. Fill in the Blanks
1.The core is
separated from the mantle by a boundary called Weichart –
Gutenberg discontinuity
2.The earthquake
waves are recorded by an instrument known as seismograph
3.Magma rises to
the surface and spreads over a vast area is known as fissure eruption
4.An example
for active volcano St. Helens USA
5.Seismology is the
study of earthquake
III. Circle the odd one
1.crust, magma, core, mantle
2.focus,
epicenter, vent, seismic
waves
3.Uttar Kashi, Chamoli, Koyna, Krakatoa
4.lava,
caldera, silica, crater
5.Stromboli, Helens,
Hawaii, Fujiyama
IV. Match the following
Earth
quake
(iii)Sudden movement
Sima
(iv)Silica and magnesium
Pacific Ring of
Fire (v)World
volcanoes
Tsunami (i)Japanese term
Mt. Kenya
(ii)Africa
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 explains 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
Question 2.
Active volcano and dormant volcano
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
Mt. Stromboli in Mediterranean Sea, St.Helens in USA,
Pinatubo in Philippines.
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.
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:
The Circum – Pacific belt
The Mid continental belt
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:
The inner most layer of the earth,
called the core has two parts, the outer core and the inner core.
The outer core is rich in iron and is
in liquid state.
The inner core is made of Nickel and
Ferrous which is in solid state.
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.
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
Question 2.
Label the parts of volcano.
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