GEO -(VII)-LESSON -2 INSIDE THE EARTH (QUESTION ANSWER)

 

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