GEO -(VII)-LESSON -2
INSIDE THE EARTH
(QUESTION
ANSWER)
NCERT EXERCISE
Q 1. Answer the
following questions.
(i) What are
the three layers of the earth?
Answer: The three
layers of earth are :
1.
Crust
2.
Mantle
3.
Core
(ii) What
is a rock?
Answer: Any natural
mass of mineral matter that makes up the earth’s crust is called a rock. The
earth’s crust is made up of various types of rocks of different texture, size
and colour.
(iii) Name
three types of rocks.
Answer: The three
types of rocks are:
1.
Igneous Rocks
2.
Sedimentary
Rocks
3. Metamorphic Rocks
(iv) How
are extrusive and intrusive rocks formed?
Answer: The molten
lava comes out of volcanoes, reaches the earth’s surface and cools down rapidly
to become a solid piece of rock. This is how extrusive rocks are formed. For
example – basalt.
When the molten lava
solidifies deep inside the earth’s crust, the rocks so formed are called
intrusive rocks. For example – granite.
(v) What
do you mean by a rock cycle?
Answer: The process of
transformation of rocks from one type to another, due to changes in certain
conditions in a cyclic manner, is called a rock cycle.
(vi) What are
the uses of rocks?
Answer: Rocks are
useful for various purposes:
·
It helps in
making roads
·
It is used in
the construction of houses and buildings
·
Small stones
are used by children in different types of games
·
They are used
in fertilisers
(vii) What are
metamorphic rocks?
Answer: The type of
rocks formed when igneous and sedimentary rocks experience heat and pressure
are called metamorphic rocks.
Q 2. Tick the
correct answer.
(i) The
rock which is made up of molten magma is
(a) Igneous
(b) Sedimentary
(c) Metamorphic
Answer: a
(ii) The
innermost layer of the earth is
(a) Crust
(b) Core
(c) Mantle
Answer: b
(iii) Gold,
petroleum and coal are examples of
(a) Rocks
(b) Minerals
(c) Fossils
Answer: b
(iv) Rocks
which contain fossils are
(a) Sedimentary rocks
(b) Metamorphic rocks
(c) Igneous rocks
Answer: a
(v) The
thinnest layer of the earth is
(a) Crust
(b) Mantle
(c) Core
Answer: a
Q 3. Match
the following.
|
(i) Core |
(a) Earth’s surface |
|
(ii) Minerals |
(b) Used for roads and buildings |
|
(iii) Rocks |
(c) Made of silicon and alumina |
|
(iv) Clay |
(d) Has definite chemical composition |
|
(v) Sial |
(e) Innermost layer |
|
(f) Changes into slate |
|
|
(g) Process of transformation of the
rock Rocks |
Answer:
|
(i) Core |
(e) Innermost layer |
|
(ii) Minerals |
(d) Has definite chemical composition |
|
(iii) Rocks |
(b) Used for roads and buildings |
|
(iv) Clay |
(f) Changes into slate |
|
(v) Sial |
(c) Made of silicon and alumina |
Q 4. Give
reasons.
(i) We
cannot go to the centre of the earth.
Answer: We cannot go to the
centre of the earth because the temperature and pressure at the centre of the
earth are very high and not just human beings, but even rocks melt at the
centre of the Earth.
(ii) Sedimentary
rocks are formed from sediments.
Answer: The small fragments
of rock that hit each other and break to reach the ground are called sediments.
These sediments are transported and deposited by wind, water, etc. and then are
compressed and hardened to form a layer of rocks called the sedimentary rocks.
This shows that sedimentary rocks are formed from sediments.
(iii) Limestone
is changed into marble
Answer: Igneous and
sedimentary rocks change into metamorphic rocks under heat and pressure. This
happens in the case of limestone. Limestone under heat and pressure changes
into marble, which is a metamorphic rock.
OTHER IMPORTANT QUESTIONS
1. Where
is the deepest mine in the world located?
(a) South America
(b) South Africa
(c) South India
(d) South Australia
2. The
depth of the deepest mine in South Africa is
(a) one km
(b) two km
(c) three km
(d) four km
3. The
upper most layer of the earth’s surface is called
(a) the crust
(b) the brust
(c) the roads
(d) the forest
4. What is
the radius of the earth?
(a) 3671 km
(b) 7163 km
(c) 6371 km
(d) 1736 km
5.Any
natural mass of mineral matter that makes up the earth’s crust is called a
(a) rock
(b) road
(c) sediment
(d) none of these
6. The
sediments are transported and deposited by
(a) wind
(b) water
(c) wind and water
(d) none of these
7.The
process of transformation of the rock from one form to another is known as
(a) road cycle
(b) food cycle
(c) rock cycle
(d) all of these
8. Which
rock is the molten magma made up of?
(a) Igneous
(b) Metamorphic
(c) Sedimentary
(d) None of these
9. What is
the latin term of Igneous?
(a) Ignis
(b) Sedimentum
(c) Metamorphose
(d) None of these
10. Rocks
which contain fossils are called
(a) metamorphic rocks
(b) igneous rocks
(c) core
(d) sedimentary rocks
Match the contents of Column A with that
of Column B.
|
Column
A |
Column
B |
|
1. Sial |
(a) Extrusive igneous rocks |
|
2. Sima |
(b) Intrusive igneous rocks |
|
3. Nife |
(c) Metamorphic rocks |
|
4. Basalt |
(d) Silica and Alumina |
|
5. Granite |
(e) Silica and Magnesium |
|
6. Slate and Marble |
(f) Nickel and Ferrous |
Fill in the blanks with appropriate words:
1. Lava is the molten magma from ……….. of the earth’s
surface.
2. Like a …………. the earth is made up of …………. layers.
3. Crust is about ………….. km on the continental mass
and ………….. km on the ocean floor.
4. The mantle makes up _______ % of the Earth by
volume.
5. Core has a radius of about ………….. km and has very
high temperature and ………..
6. Limestone under excessive heat and pressure changes
into ………….
State whether the given statements are
true or false:
1. Crust is the thickest of all the layers.
2. Core is the innermost layer of the earth.
3. Mantle extends up to the depth of 2900 km.
4. The loose sediments are hardened to form
metamorphic rocks.
5. Deccan plateau is made up of basalt.
6. Fossils are remains of dead plants and animals.
ANSWERS
|
1 |
2 |
3 |
4 |
5 |
6 |
7 |
8 |
9 |
10 |
|
B |
D |
A |
C |
A |
C |
C |
A |
A |
B |
MATCH THE
FOLLOWINGS
1-D,
2-E,3-F,4-A,5-B,6-C
FILL IN THE BLANKS
1.Interior,
2-onion, concentric, 3-35,5, 4- 57 %, 5-3500, pressure, 6- marble
TRUE OR FALSE
1-Flase , 2-true, 3-3-true, 4- Flase, 5- True, 6-true
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