HBSE 7th Class Social Science Solutions Geography Chapter 2 Inside Our Earth

Haryana State Board HBSE 7th Class Social Science Solutions Geography Chapter 2 Inside Our Earth Textbook Exercise Questions and Answers.

Haryana Board 7th Class Social Science Solutions Geography Chapter 2 Inside Our Earth

HBSE 7th Class Geography Inside Our Earth Textbook Questions and Answers

I. Answer the following questions:

Inside Our Earth Questions and Answers HBSE 7th Class Question 1.
What are the three layers of the earth?
Answer:

(1) Crust:

• The upper most layer of the earth’s surface is called crust.
• It is the thinnest of all layers.
• It is about 35 km. on the continental masses and 5 km. on the ocean floors.
• The main mineral constituents of the continental masses are silica, aluminium and sial.

(2) Mantle:

• Just beneath the crust is the mantle which extends upto 2900 km. below the crust.
• The oceanic crust and mantle consists of silica and magnesium. Thus, Sima.

(3) Core:

• The innermost layer is the core of radius 3500 km.
• It is made up of nickel and ferrous, i.e., nife.

Class 7th Geography Chapter 2 Inside Our Earth HBSE  Question 2.
What is a rock?
Answer:
Any natural mass of mineral material that makes up the earth’s crust is called a rock. The earth’s crust is made up of various types of rocks. Rocks can be of different sizes, textures, shape, colour etc.

Geography Chapter 2 Class 7 HBSE Question 3.
Name three types of rocks.
Answer:
Three types of rocks are as follows:

• Igneous Rocks
• Sedimentary Rocks
• Metamorphic Rocks.

Question 4.
How are extrusive and intrusive rocks formed?
Answer:
→ Extrusive Rocks : When the molten lava comes on the earth’s surface, it rapidly cools down and becomes solid. Rocks formed in such a way on the crust are called extrusive igneous rocks. Example : basalt.

→ Intrusive Igneous Rocks : Sometimes the molten magma cools down deep inside the earth’s crust. Solid rocks so formed are called intrusive igneous rocks. Example: granite.

Question 5.
What do you mean by a rock cycle?
Answer:
One type of rock changes into another type under certain conditions in a cyclic manner. This process of transformation of the rock from form one to another is known as rock cycle.
Example:
(a) When the molten magma cools, it solidifies to become igneous rock. These igneous rocks are broken down into small particles that are transported and deposited to form sedimentary rocks.

(b) When the igneous and sedimentary rocks are subject to heat and pressure, they change to metamorphic rocks.

Question 6.
What are the uses of rocks?
Answer:
Rocks are very useful to us :

• The hard rocks are used for making roads, houses and buildings.
• We use stones for playing games such as pitthoo (seven stones).
• Hop scotch (stapu / kit-kat) and five stones (gitti).
• Rocks are made up,of different minerals which are important to mankind, e.g., coal, natural gas and petroleum.
• Rocks are also used in industries – aluminium, gold, uranium, etc., in medicines, fertilisers etc.

Question 7.
What are metamorphic rocks?
Answer:
The igneous and metamorphic rocks are subjected to heat and pressure they change into metamorphic rocks, e.g., clay changes into slate and limestone changes into marble.

Question 2.
Tick the correct answer:
(i) The rock which is made up of molten magma is:
(a) Igneous
(b) Sedimentary
(c) Metamorphic
Answer:
(a) Igneous.

(ii) The innermost layer of the earth is:
(a) Crust
(b) Core
(c) Mantle
Answer:
(b) Core.

(iii) Gold, petroleum and coal are the examples of:
(a) Rocks
(b) Minerals
(c) Fossils
Answer:
(b) Minerals.

(iv) Rocks which contain fossils are :
(a) Sedimentary Rocks
(b) Metamorphic Rocks
(c) Igneous Rocks
Answer:
(a) Sedimentary Rocks.

(v) The thinnest layer of the earth
(a) Crust
(b) Mantle
(c) Core
Answer:
(a) Crust.

Question 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

Answer:
(i) (e)
(ii) (d)
(iii) (b)
(iv) (f)
(v) (c)

Question 4.
Give reasons :
(i) We cannot go to the centre of the earth.
(ii) Sedimentary rocks are formed from sediments.
(iii) Limestone is changed into marble.
Answer:
(i) We cannot go to the centre of the earth because the central core has very high temperature and pressure.

(ii) Sedimentary rocks are formed from sediments. Rocks roll down, crack and hit each other and are broken down into small fragments. These smaller parts are called sediments. These sediments are transported and deposits by wind, water, etc. These loose sediments then are compressed and hardened to form layers of rocks. These types of rocks are sedimentary rocks.

(iii) Limestone is changed into marble : Limetsone is a sedimentary rocks which due to excessive heat and pressure changes into marble after thousands of years and forms a metamorphic rock.

Question 5.
For fun :
(i) What are the minerals most commonly used in the following objects?
(ii) Identify some more objects made up of different minerals.

Answer:
These are made up of:

• Iron, stainless steel
• Brass and iron
• Gold and pearl
• Copper/Aluminium.

HBSE 7th Class Geography Inside Our Earth Important Questions and Answers

Very Short Answer Type Questions

Question 1.
Why is the earth called a dynamic planet?
Answer:
The earth is called a dynamic planet because it is constantly undergoing changes inside and outside.

Question 2.
What is lava?
Answer:
Lava is fiery red molten magma coming out from the interior of the earth on its surface.

Question 3.
Name the constituents of the oceanic crust.
Answer:
Silica and Magnesium.

Question 4.
What is ‘nife’?
Answer:
‘Nife’ is the name given to the core of the earth which mainly constitutes nickel and iron.

Question 5.
What happens when igneous and sedimentary rocks go under heat and pressure?
Answer:
They changes into metamorphic rocks.

Question 6.
What is the thinkess of the outer layer of the earth?
Answer:
The thickness of the outer layer of the earth is 60 km.

Question 7.
What is volcano?
Answer:
When magma from deep below forces its way up to earth’s surface, it is called volcano.

Question 8.
Which rocks are called primary or parent rocks?
Answer:
Igneous rocks are called primary or parent rocks.

Short Answer Type Questions

Question 1.
Distinguish between igneous and metamorphic rocks.
Answer:

Igneous	Metamorphic
(i) When the molten magma cools, it becomes solid and thus forms an igneous rock.	(i) Igneous rocks and sedimentary rocks can change into metamorphic rocks under great heat and pressure.
(ii) Igneous rocks are pure mineral rich rock with pure metal content, example granite and basalt.	(ii) These are a mixture of igneous as well as sedimentary rocks, clay changes into slate; limestone into marble.

Question 2.
Why are igneous rocks called primary or basic rocks?
Answer:
Our earth contains a hot molten material having high temperature and pressure deep below its lithosphere. On cooling and solidification of the matter igneous rocks are formed. They make up about two-thirds of the earth’s crust. Therefore, they are called basic or primary rocks.

Question 3.
Formation of rocks is a slow process. Why?
Answer:
Formation of rocks , is a slow process because:

• Climate breaks the parent rocks into many smaller pieces.
• Topography or elevation helps in weathering of the rocks.
• Plants and animals organism help in weathering of rocks.

For all these processes, time factor plays a major role.

Question 4.
What do the words igneous, sedimentary and metamorphic mean.
Answer:

• The word Igneous drives from Latin word Ignis meaning Fire.
• The word sedimentary is derived from a Latin sediments meaning settle down.
• The word metamorphic derives from a Greek word metamorphise meaning change of form.

Question 5.
Give two examples of each of the following :
(а) Igneous rocks
(b) Sedimentary rocks
(c) Metamorphic rocks.
Answer:
(a) Land and zinc
(b) Coal and limestone
(c) Graphite and marble:

Long Answer Type Questions

Question 1.
How are different kinds of rocks formed?
Answer:
(i) Igneous rocks : When the molten magma cools, it becomes solid. Rocks formed in this way are called igneous rocks. They are also called primary rocks. They are of two types- intrusive rocks and extrusive rocks.
(a) Extrusive rocks : When molten lava comes on the earth’s surface, it rapidly cools down and becomes solid. Rocks formed in this way on the crust are called extrusive igneous rocks. For example, basalt.

(b) Intrusive rocks : Sometimes the molten magma cools down deep inside the earth’s crust. Solid rocks so formed are called intrusive igneous rocks. Since they cool down slowly they form large grains. For example, granite.

(ii) Sedimentary rocks : Small fragments of rocks are called sediments. These sediments are transported and deposited by wind, water, etc. These loose sediments are compressed and hardened to form sedimentary rocks. For example, sandstone is made from grains of sand.

(iii) Metamorphic rocks : When igneous and sedimentary rocks are subjected to great heat and pressure they changes into metamorphic rocks. For example,k clay changes into slate and limestone into marble.

Question 2.
Distinguish between rocks and minerals.
Answer:

Rocks	Minerals
(i) Rock is an aggregate of minerals.	(i) Minerals contain ore and have atomic structure.
(ii) A rock is a natural solid material forming the earth’s crust.	(ii) A mineral is a natural inorganic compound formed in the rocks.
(iii) Rocks are mainly of three types :	(iii) There are about 2000 types of minerals.
(iv) A rock does not have a definite chemical composition.	(iv) Minerals have a definite chemical composition.

Question 3.
Distinguish between crust and core.
Answer:

Crust	Core
(i) It is the upper most layer of the earth’s surface.	(i) It is the inner most layer of the earth’s surface.
(ii) The main mineral constituents are silica and alumina that is, SIAL.	(ii) The main mineral constituents are nickel and ferrous that is NIFE.
(iii) The density of crust is only 1.5 km.	(iii) The density of core is only 5.1 km.
(iv) The crust is about 35 km. on continental masses and only 5 km. on the ocean floors.	(iv) The core has a radius of 3500 km.
(v) The temperature doesn’t rise more than 50° or 55°C.	(v) The temperature is much higher and have pressure.

Question 4.
Distinguish between mantle and core.
Answer:

Mantle	Core
(i) It is the middle or centric layer of the earth just beneath the crust.	(i) It is the inner most layer of the earth.
(ii) The mantle comprises of mineral constituents like silica and magnesium that is SIMA.	(ii) The main mineral constituents are nickel and furrous that is NIFE.
(iii) The mantle has a density of 3.5 km.	(iii) The core has a density of 5.1 km.

Inside Our Earth Class 7 HBSE Notes

• Core : The innermost layer of the earth.
• Crust: The topmost layer of the earth.
• Mantle : The layer of the earth that lies beneath the crust.
• Fossils : The remains of the dead plants and animals trapped in the layers of rocks are called fossils.
• Tectonic Activities : It is activities that affect the large-scale processes of earth.
• Igneous rocks : Rocks which are formed by solidification of magma are called igneous rocks.
• Sedimentary Rocks : The rocks which are formed by sediments laid down usually on the sea-floor or lakes are known as sedimentary rocks.
• Metamorphic Rocks : The rocks which are formed due to change in igneous and metamorphic rocks under great heat and pressure.
• Graphite : A soft substance used for manufacturing pencils and crucibles.
• Rock Cycle : Movement of rocks in cyclic order whereby they are recycled and again formed