WBBSE Class 8 Geography Solutions Chapter 3 Rocks

Detailed explanations in West Bengal Board Class 8 Geography Book Solutions Chapter 3 Rocks offer valuable context and analysis.

WBBSE Class 8 Geography Chapter 3 Question Answer – Rocks

Textbook Page no. 23.

Question 1.
Why are crystals not formed in sedimentery rocks?
Answer:
The hardness of the sedimentery rock is less than igneous rock. Therefore, sedimentery rocks do not have crystalline structure.

Question 2.
Why are fossils not found in igneous rocks?
Answer:
Due to excessive pressure and heat the inagma from earth’s interior comes out as lava and solidifies either on the earth’s surface or in the earth chamber to form igneous rock. So the fossil is not found.

Question 3.
From which type of rock is extraction of minerals convenient and why?
Answer:
In sedimentary rock mining is easy. Near about 7-10 crore years ago many organisms got burried under the layer of the sedimentary rocks. For the excessive pressure of upper layer and heat of the earth chamber the remaining parts of the body changes into the solution of hydrogen and carbon and different types of minerals are formed. So only the porous layer of sedimentery rock is called the store house of the minerals.

Textbook Page no. 26.

Question 1.
Which rocks are laid between and near a pair of railway tracks? Why are these rocks found here?
Answer:
In between railway track generally granite is found. It is because granite is very much resistant to erosion.

Question 2.
why does a piece of granite glitter?
Answer:
Glittering substance like mica is present in granite. This is because granite glitters.

Question 3.
Which rock is used to make a pencil lead?
Answer:
The lead of the pencil is made up of graphite, a metamorphic rock.

Question 4.
I am glittery, black or white. I am soft and malleable. I am a main constituent mineral of Granite. Can you say who I am?
Answer:
Quartz.

Identify me Page no. 27.

Question 1.
I have a smooth and attractive appearance. I am used in making floors. I have been used in constructing famous archetectural landmarks including the Victoria Memorial.
Answer:
Marble.

Question 2.
I am a very hard, fine grained grey black rock. I am commonly used in constructing roads. Water can easily pass through me.
Answer:
Gneiss.

Match the following :
Answer:

1. Limestone	Stalactite.
2. Sandstone	Sedimentary Rock.
3. Granite	Rounded dand form.
4. Great pressure	A cause of metamorphosis of rock.
5. Basalt	Flat topped landform.
6. Marble	Metamorphic rock.
7. Potassium	Plagioclase Feldsper.
8. Calcium Sulphate	Gypsum.

Class 8 Geography Chapter 3 Question Answer West Bengal Board – Rocks

Multiple Choice Questions& Answers : (1 mark for each question)

Question 1.
The characteristics of landform formed by Granite-
i) cavesquare
ii) flatsquare
iii) roundsquare
iv) steep slope
Answer:
iii) round.

Question 2.
The characteristics of landform formed by basalt-
i) cavesquare
ii) flatsquare
iii) roundsquare
iv) steep slope
Answer:
ii) flat.

Question 3.
The characteristics of landform formed by limestone-
i) cavesquare
ii) flatsquare
iii) roundsquare
iv) steep slope
Answer:
i) cave.

Question 4.
The characteristics of landform formed by sandstone-
i) cavesquare
ii) flatsquare
iii) roundsquare
iv) steep slope
Answer:
iv) steep slope

Question 5.
Slate is used in making-
i) cementsquare
ii) blackboardsquare
iii) iron industrysquare
iv) roads
Answer:
ii) blackboarc

Question 6.
Peat coal can be metamorphosed to graphite due to-
i) great pressuresquare
ii) chemical reactionsquare
iii) great heatsquare
iv) none of these
Answer:
iii) great heat

Question 7.
Amphibolite is the metamorphosed form of-
i) granitesquare
ii) sandstonesquare
iii) peat coalsquare
iv) mud stone
Answer:
i) granite

Question 8.
Victoria Memorial is made of-
i) granitesquare
ii) basattsquare
iii) mudstonesquare
iv) marble
Answer:
iv) marble

Question 9.
Fossils are found only in-
i) igneous rocks
ii) metamorphic rocks
iii) sedimentary rocks
Answer:
iii) sedimentary rocks

Question 10.
Sorrect metamorphosed form is-
i) graniterightarrow marble
ii) limestonerightarrow graphite
iii) sandstonerightarrow amphibolitesquare,
iv) basaltrightarrow amphibolite
Answer:
iv) basaltrightarrow amphibolite

Correct the wrong : (1 mark for each question)

Question 1.
The extrusive igneous rocks are generally fine grained because lavas after coming over the surface are slowly cooled and solidify.
Answer:
The extrusive igneous rocks are generally fine grained because lavas after coming over the surface are quickly cooled and solidify.

Question 2.
The amount of basic oxide in peridotite rock as 55%-45%.
Answer:
The amount of basic oxide in peridotite rock is more than 55%.

Question 3.
Andresite is one type of intrusive igneous rock.
Answer:
Andresite is one type of extrusive igneous rock.

Question 4.
Land forms developed on the regions of granite rock are mainly of round shaped.
Answer:
Land forms developed on the regions of granite rock are mainly of flat shaped.

Question 5.
The granite is composed of otvin and pyroxene.
Answer:
The granite is composed of mica and hornblends.

Question 6.
Igneous rocks are the store house of coal, petroleum and natural gas.
Answer:
Sedimentary rocks are the store house of coal petroleun and natural gas.

Question 7.
High permeability increases the water retaining capacity.
Answer:
High permeability reduces the water retaining capacity.

Question 8.
Fossil is found in metamorphic rocks.
Answer:
Fossil is found in sedimentary rocks.

Question 9.
Chemically formed sedimentary rock is conglomerate.
Answer:
Mechanically formed sedimentary rock is conglomerate.

Question 10.
Limestone is resistant to erosion and less permeable.
Answer:
Limestone is not resistant to erosion and highly permeable.

Question 11.
Bright crystalline structure is found in sedimentary rocks.
Answer:
Bright crystalline structure is found in igneous rocks.

Question 12.
Gneiss is harder than granite.
Answer:
Gneiss is less harder than granite.

Question 13.
The region predominated by limestone is suitable for constructing high rise building, roads etc.
Answer:
The region predominated by granite is suitable for constructing highrise building, roads etc.

Question 14.
Quartz is used for making glass.
Answer:
Quartz is used for cutting glass.

Question 15.
Mica is good conductor of heat and electricity.
Answer:
Mica is poor conductor of heat and electricity.

Question 16.
In Mah’s scale the value of harlness of diamond is 8.
Answer:
In Mah’s scale the value of hardness of diamond is 10.

Question 17.
The main element of plagioclase feldsper is Potassium.
Answer:
The main element of plagioclase feldspar is Sodium.

Question 18.
The main occupation of Chotanagpur plateau region is agriculture.
Answer:
The main occupation of Chotanagpur plateau region is mining and mine-based industry.

Question 19.
The soil derrived from basalt rock is infertile.
Answer:
The soil derrived from basalt rock is suitable for wheat and cotton.

Question 20.
The grains of sandy soil is smaller.
Answer:
The grains of sandy soil is bigger.

Question 21.
Sandy soil is found in North Indian plain.
Answer:
Alluvial soil is found in North Indian plain.

Question 22.
The fertility of clayey soil is more.
Answer:
The fertility of clayey soil is medium.

State whether True or False : (1 mark for each question)

1. In Mah’s scale the mineral with value of hardness 7 is Quartz.
2. Limestone disolves in water:
3. Sandstone is used in architectural works.
4. The colour of shale may be yellow, red, orange, pink etc.
5. Rocks can be metamorphosed in different ways.
6. When sedimentary rock metamorphosed it becomes brittle.
7. Marble is the metamorphosed form of limestone.
a. It is easy to mine from marble.
9. The metamorphosed form of sandstone is Qurartzite.
10. No landform is found in the limestone dominated region.
11. Feldspar is as smooth as slate.
12. Mica is used for making glass.
13. Regolith is the main composition of soil formation.
14. The soil made up of basalt is white.
15. The alluvial soil is the most suitable for agriculture.
Answer:
1 true
2. false
3. true
4. false
5. true
6. false
7. true
8. false
9. true
10. false
11. true
12. false
13. true
14 false
15. true

Fill in the blanks : (1 mark for each question)

1. __________ is a clastic rock.
2. Crystal may be __________ or hexagonal in shape.
3. Cometite is a _______ rock.
4. The diameter of the particle of gabbro is _________ mm.
5. The continental plate is made up of _________.
6. The chief constituent minerals of Basalt is _________.
7. __________ are found is sedimentery rock.
8. High _________ reduces the water retaining capacity of rocks.
9. ________ is the sedimentery rock of silicate.
10. The golden fort of Joysalmeer is made up of ___________.
11. Graphite is the _________ form of peat coal.
12. The example of a rock with fine grains is ___________.
13. Sedimentery rocks become less ________ when metamorphosed.
14. Marble readily melts in _________
15. ___________ is not as hard as ganite.
16. Sometimes lime formation may rise from the cave floors which is called ________.
17. For the construction high rise buildings and road the region with __________ is suitable.
18. Diamond is metamorphosed torm of __________.
19. Most of the rock forming minerals is made up of ________ eliment.
20. Mica may be of the white ____________.
21. Mica is _________ of heat and electricity.
22. ____________ is a hydrated crystal of Calcium Sulphate.
23. The influence of __________ is verv much evident in nature.
24. The soil predominated by Zypsum is soft and ___________ in colour.
25. The main occupation in Chotanagpur plateau region is mining and __________.
26. Characteristic features of a soil usually depend on the ____________ of the layer of rock underneath.
27. Soil derived from Basalt is suitable for growing ___________.
28. The soil derived from _________ is found in Chotanagpur plateat.
29. Grains of minerals are very _________.
Answer:
1. conglomerate
2. cubic
3. ultra basic rock
4. 3, 5. granite
6. Pyroxene
7. layers
8. permeability
9. flint
10. sandstone
11. metamorphose
12. mudstone
13. brittle
14. acid
15. granite
16. stalagmites
17, granite rock
18. carbon
19.8,20. muscovite
21. poor conductor
22. zypsum
23. mineral
24. light yellow
25. mining based industry
26. nature
27. wheat and cotton
28. granite
29. fine.

Match the column A with column B.

Column A	Column B
a) In igneous rocks	i) crosion resistant rock
b) Sedimentery rocks	ii) porous sedimentary rocks
c) Basalt is highly	iii) mainly from basalt
d) Sand remains loose and light	iv) crystalline structure is found
e) Shale is widely used	i) heat and electricity
f) Petrolium is available only in the	ii) are highly permeable
g) Constracting dams in a limestone	iii) of calcium sulphate
h) Black soil is made	iv) when it is dry
i) Gypsum is a hydrated crystal	i) terrain is not the right thing to do
j) Mics is a poor conductor of	ii) in making roof-tiles of buildings

Answer:
a) In igneous rocks crystalline structure is found.
b) Sedimentery rocks are highly permeable.
c) Basalt is highly erosion resistant rock.
d) Sand remains loose and light when it is dry.
e) Shale is widely used in making roof-tiles of buildings.
f) Petrolium is available only in the porous sedimentary rocks.
g) Constracting dams in a limestone terrain is not the right thing to do.
h) Black soil is made mainly from basalt.
i) Gypsum is a hydrated crystal of calcium sulphate.
j) Mics is a poor conductor of heat and electricity.

Very Short Questions& Answers : (1 mark for each question)

Question 1.
How can be igneous rock divided according to origin?
Answer:
According to origin igneous rock is of two types.

Question 2.
Name an extrusive igneous rock.
Answer:
Basalt.

Question 3.
Name a hypabyssal igneous rock.
Answer:
Dolorite

Question 4.
At what percent Silica is present in acidic rock?
Answer:
More than 60%.

Question 5.
What is the diameter of the particle of extrusive rock?
Answer:
‘ess than 1 mm.

Question 6.
At what amount basic oxide is present in acidic rock?
Answer:
More than 55%

Question 7.
How are the lasdforms developed with granite rock?
Answer:
Round shaped.

Question 8.
How are the land forms developed with basalt rock?
Answer:
Flat shaped.

Question 9.
What is the diameter of the particle of hypabyssal rocks.
Answer:
More than 3 mm.

Question 10.
Which rocks have high permeability?
Answer:
Sandstone.

Question 11.
In which rock layer mineral oil and natural gas are found?
Answer:
Only in porous sedimentary rock.

Question 12.
Name a sedimentary rock iron stone typed.
Answer:
Haematite.

Question 13.
What is rock?
Answer:
Rocks are homogenous or heterogenous aggregates of one or more minerals.

Question 14.
What minerals the granite rock is composed with?
Answer:
Granite rock is composed with quartz, feldsper. mica and hornblends.

Question 15.
What minerals the limestone is composed with?
Answer:
Limestone is composed with calcite.

Question 16.
What is petrology?
Answer:
The special branch of science which deals with the rocks and their characteristics is known as petrology.

Question 17.
What is mineralogy?
Answer:
The branch of science which deals with minerals is called mineralogy.

Question 18.
What is the other name of igneous rocks?
Answer:
The other name of igneous rock is primary rocks.

Question 19.
Why is the grains of extrusive igneous rock are generally fine?
Answer:
The grains of extrusive igneous rock are generally fine because lavas after coming over the surface are quickly cooled and solidified.

Question 20.
What are the different types of intrusive igneous rocks.
Answer:
The different types of intrusive igneous rocks are hypabyssal and plutonic.

Question 21.
What type of rock is dolerite?
Answer:
Dolerite is one type of hypabyssal igneous rock.

Question 22.
How are crystals formed in igneous rocks?
Answer:
Crystals are formed as the atoms of the mineral water which remain in like veins after cooling of the rock.

Question 23.
Name some crystals.
Answer:
Some crystals are quartz. topaz, calcite. diamond.

Question 24.
What is the shape of the crystal?
Answer:
Crystals are either crystal or hexagonal in shape.

Question 25.
Give an example of intermediate rock? What amount of basic acid is present in it.
Answer:
An example of intermediate rock is andesite in whiç basic oxide is 45-35%.

Question 26.
At what amount of Silica is present in peridotite rock?
Answer:
More than 45% of silica is present in peridotite.

Question 27.
What type of rock is kimberlite.
Answer:
Kimberlite is ultra basic rocks.

Question 28.
What is the diameter of Granite rock?
Answer:
The diameter of granite rock is more than 3 mm.

Question 29.
What are the rock forming minerals of basalt?
Answer:
The chief constituent minerals of basalt are feldspar, olivin and pyroxene.

Question 30.
What is the diameter of the particle of Micro-diorite?
Answer:
The diameter of the particle of micro-diorite is 1-3 mm.

Question 31.
What is permeability?
Answer:
Permeability means penetration of liquid and gaseous substances through the rock.

Question 32.
What is porosity?
Answer:
Porosity means the ratio between the voids and total volume of a given rock mas.

Question 33.
Give an example of pyroelastic rock.
Answer:
An example of pyroelastic rock is tuff.

Question 34.
Name a chemically formed sedimentary rock.
Answer:
A chemically formed sedimentery rock is Gypsum.

Question 35.
What is diatom?
Answer:
Diatom is organically formed sedimentary rock.

Question 36.
Name a calcareous sedimentery rock.
Answer:
Limestone.

Question 37.
What is the scientific name of limestone?
Answer:
Calcium Carbonate.

Question 38.
How is limestone used?
Answer:
Limestone is used as a raw material in making cement and in iron and steel industry.

Question 39.
With which stone the Khajuraho temple is made?
Answer:
The Khajuraho temple is made up of sandstone.

Question 40.
Which rock is used to make roof tiles?
Answer:
Slate is used to make roof tiles.

Question 41.
How is slate formed ‘slab?
Answer:
Under tremendous pressure slab metamorphoses to form slate.

Question 42.
What is phyllite?
Answer:
Phyllite is one type of slate.

Question 43.
Into which peat coal is transformed?
Answer:
Peat coal is transformed into Graphite.

Question 44.
Which rock is used for making black board.
Answer:
Slate is used for making black board.

Question 45.
Which rock is used for the construction of road?
Answer:
Metamorphic rock, Granite is used for the construction of road.

Question 46.
Name an acidic rock.
Answer:
An acidic rock is Basalt.

Question 47.
Is the Decan plateau is the part of Decan trap?
Answer:
The dalite like land from with flat top at Panchagani Mahabaleshwar region is the part of Decan trap of Decan plateau.

Question 48.
What is Stalactites and Stalagmites?
Answer:
Stalactites and Stalagmites are limestone cave.

Question 49.
Where is granite rock found?
Answer:
Granite rock is found in entire Chotanagpur region including Ranchi.

Question 50.
Why is constructing dams and reservoirs in a limestone terrain is not the right thing to do?
Answer:
It is because rivers or rain water can crode limestone by solution. So the dam may easily crack.

Question 51.
In which region multistoried buildings and excessive length of road are not advisable?
Answer:
Multistoried buildings and excessive length of road are not advisable in limestone terrains.

Question 52.
What is the colour of ortho claye?
Answer:
Pink.

Question 53.
Name the rock forming minerals.
Answer:
Silicon, Oxygen.

Question 54.
Which mineral is used for making ornaments and cutting glass and stone?
Answer:
Quartz.

Question 55.
What is the main element of Plagioclase feldspar?
Answer:
The main element of plagioclase feldsper is Sodium.

Question 56.
What is the element of orthoclase?
Answer:
The main element of orthoclase is Potassium.

Question 57.
What is the use of feldspar?
Answer:
Feldspar is used in glass and ceramic industry.

Question 58.
Name a soft mineral.
Answer:
Zypsum.

Question 59.
What is Malı’s scale?
Answer:
Mah’s scale of hardness measures the hardness of minerals.

Question 60.
What is the hardness of corundum measured in Mah’s scale?
Answer:
The hardness of Corundum in Mah’s scale is 9.

Question 61.
How is the soil in the region with Gypsum?
Answer:
The soil is soft light yellowish in the region with Gypsum.

Question 62.
Name a soil with excessive mineral.
Answer:
Laterite soil and red soil.

Question 63.
Why is the soil, made up of granite, red?
Answer:
This is because the oxide of iron present in this soil at high amount.

Question 64.
What type of soil found in the desertic area of Rajasthan?
Answer:
Sandy soil.

Question 65.
Where is Mangrove forest found?
Answer:
Mangrove forest is found at the sea coast with saline soil.

Short Questions & Answers : (2 marks for each question)

Question 1.
Mention one difference of homogeneus and heterogeneus mixture.
Answer:
In homogeneus mixture all elements remain in equal ratio everywhere but in heterogeneus mixture all the elements lie in equal ratio in different places.

Question 2.
What is fossil? In which rock fossil is found?
Answer:
Marine plants and animals sometimes come within the beds of the sediments during compaction of layers to form sedimentery rock. Later dead remains of the organism leave their imprint into the layers of sediment after being solidified. This is called fossils.

Question 3.
What is rock cycle?
Answer:
In nature the formation of rocks and transformation of rocks have occured in cycling way in a specific method. The complete cyclic process of formation of rocks and their changes frum one type to the other is called the rock cycle.

Question 4.
What is regolith?
Answer:
Natural agents like river wind, rainfall, sea-waves, glacier etc. degrade rocks and minerals over a long time to form loose deleres of rock. This delere’s then interacts naturally with water air and organic matter to form soil. This delere’s of degraded rocks is called regolith.

why the Chotanagur Plateau is called ‘the store house of minerals’.
Answer:
Chotanagpur Plateau in India is rich in minerals like iron, copper, bauxite, manganese, dolomite etc. So it is called the storehouse of minerals’.

Question 6.
What is limestone?
Answer:
Limestone is a calcareous sedimentary rock. It is not generally soluble in water. But it gets readily dissolved in rainwater or acid solutions when it is transformed to calcium bicarbonate. Limestone may be white, grey, green or blackish in colour.

Question 7.
What is sandstone?
Answer:
Sandstone is a sedimentary rock rich in sand. It is resistant to erosion in spite of being highly porous and permeable. Architects use it in making epitaphs and monuments. It is yellow, orange, red, pink, white or grey in colour.

Question 8.
What is Marble?
Answer:
Marble is the metamorphosed form of lime stone. It is smoothy, glittery and attractive. It is available in a wide variety of colours including white, green, grey, yellow and blue. It is extensively used by architects.

Question 9.
What is slate?
Answer:
It is the metamorphosed form of mudstone or shale. It is smooth and biuish grey to black in colour. It is arranged into thin layers and can be easily broken. They are used in making oof tiles and blackboards and can be used as a surface for writing.

Question 10.
What is gneiss?
Answer:
This is a hard and resistant rock. The minerals in it are often arranged in bands. So this is called a banded rock. Extarcting a certain mineral from it is thus convenient. This rock is widely used to make roads and in other constructions.

Question 11.
What is quarz?
Answer:
Quartz is very hard, often whitish and hexagonal crystals. It is the main constituent of granite and Basalt. These rocks are very resistant to erosion due to the presence of quartz in them. It is used as stone cutter, glass cutter and in ornaments.

Question 12.
What is mica?
Answer:
Mica is lustrous, smooth, flaky and brittle in nature. It may be of the 1 , hite Muscovite or black Biotite varieties. Its presence gives granite its luster. Mica is a conductor of heat and electricity. It is used in preparing electrical goods.

Question 13.
What is shale?
Answer:
It is a sedimentary rock rich in clay. It is blackish grey in colour. Thin layers are seen in it. It is soft snd brittle rock. This rock is widely used in making roof-tiles of buildings.

Long Questions & Answers : (3 marks for each question)

Question 1.
Write a short note on Igneous Rock.
Answer:
It is also known as Primary rocks as these were the first rocks to originate on earth. This is also called primary rock. According to origin igneous rock is of two types Intrusive and Extrusive igneous rocks. Extrusive igneous rocks are generally fine grained besause lava after coming over the surfsce, is quickly cooled and solidified e.g-basalt, obsedian. When the rising magma foes not reach the earth’s surface, butis cooled and solidified below the surface of the earth, it is called intrusive igneous rock e.g-granite, dolerite.

Question 2.
Write a short note on sedimentary rock.
Answer:
Sediments and debris derived from the source through erosion snd transportation by natural agents of erosion like river, glacier, wind, sea waves are deposited under the water. Thus this types of rocks are called sedimentary rocks. Chalk, sandstone, mudstone are the example of sedimentary rocks. Layer and mud cracks are found in this rocks. Fossils are found in this rocks. These rocks are porous and also fragile. This type of rocks are highly permeable. Different sedimentary rocks have different degree of erosion resistant capacity. Sedimentary rock is the store house of coal, petroleum and natural gas. On the basis of composition sedimentary rocks are classifed into three groups i) mechanically formed sedimentary rocks, ii) Chemically formed sedimentary rocks, iii) Organically formed sedimentary rocks. Sedimentary are also classified according to the origin. Those are : i) Clastic rocks. ii) Non-clastic rocks.

Question 3.
Write a short note on metamorphic rock.
Answer:
Metamorphic rocks are formed by changing the physical and chemical characters of igneous and sedimentary rocks due to influence of great heat and pressure.
Metamorphic rocks may be crystalline. When an igneous change into metamorphic rocks, it is smoother, more lustrous and more crystalline. When a sedimentary rocks changes into metamorphic rocks it becomes less brittle. Besides, great heat and pressure erase out the fossils in a sedimentary rocks during metamorphism. Marble, slate are common metamorphic rocks.

Question 4.
What is rock cycle? Explain.
Answer:
The magma of asthenosphere comes out on the earth surface after eruption and flows of lava. Then cools to form igneous rock, or cools and solidify in the earth chamber to form igneous rocks. In due course of time the igneous rocks get eroded and accumulate under the sea, lake, ocean. After a long period of time this sediment changes this sedimentary rocks then this igneous rocks or sedimentary rocks change into metamorphic rock due to great heat, pressure or chemical reaction. Later for tiectonic movement the rocks may be brough back to interior of this earth where they melt and recycle as magma. Origin of rocks andtheir transformations and metamorphosis goes on in a cycle. The complete recycle process of formation of rocks and there change from one type to other is called the rock cycle.

Question 5.
What is the influence of mineral in soil?
Answer:
The influence of mineráls in nature is very distinct. The surface of the soil rich in iron and bauxite is very hard and red in colour. On the other hand soil, rich in Zypsum is soft and yellow in colour. Soil, rich in soft calcite, is erosion-prone. The places, where the mineral oil is found, are made up of porous, permiable sedimentary rocks. The soil with exclusive miniral is not fit for agriculture.

Question 6.
Write about formation of soil from rocks.
Answer:
For the action of different natural agents like river, wind, rainfall, ocean current, glacier current, the rock forming minerals are eroded and exist as the rock particle which mixes with water, air and different organic matter later and forms soil. The soil made up of basalt rock is black and is found in the Decan plateau region of India. The sandy soil is form in this that region with sandstone.

The colour of the soil is light, yellowish to grayish brown. The soil is not fit for agriculture. Sandy oil is found in the desertic region Rajasthan. In alluvial soil grains of the minerals are very fine. This type of soil is very fit for agriculture. The soil of North Indian plain is some in nature. The soil which is enrich with iron and Aluminium oxide excessively is called Laterite soil. This type of soil is not fertile. Laterite soil is found in Chota Nagpur and Meghalaya plateaus. Saline soil is found at the sea coast. Mangrove vegetation grows in this soil. This soil is found in the Sundarban region of West Bengal.

Question 7.
What is Karst Topography?
Answer:
There are natural caves in Cherrapunji-Mawsynram. Narrow, pointed, rocky structures hang from the seiling in these caves. These are limestone caves. The lime formations hanging from the roof are called Stalactites. Sometimes similar lime formations may rise from the cave floors. They are called Stalagmites. Rising Stalagmites and drooping Stalactites may join to form limestone pillars. This typical assemblage of landform is called Krast Topography.

Question 8.
Write three characteristics of igneous rocks.
Answer:
Three characteristics of igneous rocks-
i. Joints and cracks are very common in these rocks, so these are highly permeable.
ii. Crystaline structure is found.
iii. The Colour of these rocks vary from light to dark.

Question 9.
Write three characteristics of sedimentary rocks.
Answer:
Three characteristics of sedimentary rocks-
i. Layers and mudcracks are found in this type of rocks.
ii. Different sedimentary rocks have different capacity to resist c.osion.
iii. Reserves of coal, petroleum and natural gas are found within these rocks.

Question 10.
Write three characteristics of metamorphic rocks.
Answer:
Three characteristics of metamorphic rocks-
i. Metamorphism usually hardens igneous and sedimentary rocks.
ii. Igneous rocks get smoother, morelustrous and more crystalline with metamorplifsm.
iii. Sedimentary rocks become less brittle when metamorphosed.