GEOGRAPHY CHAPTER 2: INSIDE OUR
EARTH
Important
questions with answers
1. Answer the following questions.
(i)
What
are three layers of the earth?
Answer: The
three layers of the earth are crust, mantle and core.
(ii)
What
is a rock?
Answer: A
rock is a naturally occurring solid mass of mineral matter that constitutes the
earth’s crust.
(iii)
Name
three types of rocks?
Answer: The
three types of rocks are
·
Igneous rocks
·
Sedimentary rocks and
·
Metamorphic rocks.
(iv)
How
are extrusive and intrusive rocks formed?
Answer:
When molten magma comes out into the surface of the earth and cools down
rapidly, extrusive igneous rocks are formed.
On the other hand,
sometimes the molten magma remains inside the crust of the earth and cools down
there itself. The rocks thus formed are called intrusive igneous rocks.
(v)
What
do you mean by a rock cycle?
Answer: The natural process by which rocks change its type again and again and eventually
returns back to its original type, completing one cycle is called a rock cycle.
(vi)
What
are the uses of rocks?
Answer: Rocks
are used for several purposes. A few of the uses of rocks are listed below.
·
Rocks are used in the construction of
houses, bridges etc.
·
Some precious stones are also used in
making ornaments.
·
Small pieces of rocks are also used to
play different games.
(vii)
What
are metamorphic rocks?
Answer: When
Igneous and sedimentary rocks are subjected to great amount o heat and
pressure, metamorphic rocks are formed.
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 at the centre of
the earth is very high. Moreover, it is not possible to dig a hole to the centre
of the earth as till now human beings are able to dig a hole only about 6 Km,
and to go to the centre of the earth we have to dig a hole of 6371 Km.
(ii)
Sedimentary
rocks are formed from sediments.
Answer: Rocks
are broken down into smaller pieces and transported by wind, water and various
other agents over a long duration of time. These smaller pieces are called
sediments. These sediments got compressed and hardened over the years to form
layers of rock called sedimentary rock.
(iii)
Limestone
is changed into marble.
Answer; We
know that under great temperature and pressure, the sedimentary rock gets converted
into metamorphic rock. Limestone is an example of sedimentary rock and marble
is an example of metamorphic rock. Therefore, limestone under a great amount of
heat and pressure gets converted into marble.
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