Detailed explanations in West Bengal Board Class 7 Geography Book Solutions Chapter 6 Rock and Soil offer valuable context and analysis.
WBBSE Class 7 Geography Chapter 6 Question Answer – Rock and Soil
(Page no. 62)
Let’s get the job on hand done….
|ORIGIN OF ROCKS||TYPES OF ROCK|
|1. By sedimentation||Sedimentary rock.|
|2. By accumulation of Lava||Igneous rock|
|3. By heat and pressure in the earth’s interior||Metamorphic rock|
|Charecteristics of RoCK||TIPES OF ROCK|
|1. Light and brittle||Sedimentary rock|
|2. Hard and resistant to erosion||Metamorphic rock.|
(Page no. 64)
Class 7 Geography Chapter 6 Question Answer West Bengal Board – Rock and Soil
Multiple Choice Questions & Answers : (1 mark for each question)
The rock that accumulates on the ocean floor is –
i) igneous rock
ii) sedimentary rock
iii) metamorphic rock
ii) Sedimentary rock.
The rock that is used in making cement is –
ii) sand stone
iii) lime stone
iii) Lime stone.
Marbel is –
i) igneous rock
ii) sedimentary rock
ii) metamorphic rocks
iii) Metamorphic rock.
Sedimentary rock is –
i) sand stone
i) Sand stone.
The stones that are used as building materials –
iv) sandstone and mudstone
iv) sandstone and mudstone
The grains of sandy soil is –
Loamy soil contains-
i) more sand, less clay
ii) equal sand and clay
iii) less sand, more clay
ii) equal sand and clay
The animals help to loosen the soil-
iv) all of these
iv) all of these
Fill in the blanks : (1 mark for each question)
1. Granite is one type of ________.
2. Tajmahal is made of __________.
3. Soil forms faster in warm and rainy ___________.
4. Dead remains of organisms supply ___________ to a soil.
5. Sandstone, mudstone, limestone are examples of _________ rocks.
6. Plants and animals form a very __________ part soil.
7. soil __________ is best suited for cultivation.
8. The hard outer shell of the earth is made of __________.
9. ____________ soil has bigger grains and bigger spaces between the grains.
10. Sandy soil absorbs ____________ in no time.
11. The __________ soil is found at the bank of the river.
12. The ability of holding water is more is ___________ soil.
State whetherTrue or False : (1 mark for each question)
1. The earth was a ball of fire when it was born.
2. Igneous rocks break down easily.
3. Sandstone is used as raw material in cement.
4. Metamorphic rocks are hardy and resistant to errosion.
5. Heat from the sun, rain drop, wind, river water etc break down the rocks.
6. Soil formation is influenced by several factors.
7. Soil is classified on the basis of their taste.
8. Basalt is the example of sedimentary rock.
9. Sedimentary rocks are soft and brittle.
Match the following : (1 mark for each question)
Match column A with column B.
|a) Igneous rock is||i) soft and brittle|
|b) Granite and Basalt are||ii) warm and rainy climates|
|c) Limestone is used||iii) supply nutrients to soil|
|d) Sedientary rock is||iv) example of igneons rock|
|e) Metamorphic rock is||v) very hard|
|f) Soil forms faster in||vi) equal sand and clay|
|g) Dead remains of organisms||vii) resistant to erosion|
|h) Loamy soil contains||viii) in cement|
a) Igneous rock is very hard.
b) Granite and Basalt are example of igneous rock.
c) Limestone is used in cement.
d) Sedientary rock is soft and brittle.
e) Metamorphic rock is resistant to erosion.
f) Soil forms faster in warm and rainy climates.
g) Dead remains of organisms supply nutrients to soil.
h) Loamy soil contains equal sand and clay.
Very Short Questions & Answers : (1 mark for each question)
What type of rocks are those which lie on the railway track?
The rocks on the railway track are igneous rock.
Which rock can resist erosion?
Metamorphic rock can resist erosion.
Which rocks are used as housebuilding materials?
Sandstone and mudstone are used as house building materials.
Which soil is suitable for agriculture?
Loamy soil is suitable for agriculture.
What do the rocks transform into after erosion?
After erosion the rocks transform into soil.
Which soil can not hold water?
Sandy soil can not hold water.
Which soil is used for making idol?
Clayey soil is used for making idoal.
What is the Earth’s surface?
The outmost level of the land or sea is known as the Earth’s surface.
What are rocks?
Rocks are the compound of minerals which form the Earth’s surface.
How are the rocks classified?
Rocks are classified into three groups- igneous, sedimentary and metamorphic.
What is soil?
The smooth and loose upper most rock layer of the earth’s surface is called soil.
How is the soil classified?
The soil is classified into three group-sanday, clayey and loamy.
Short Questions & Answers : (2 marks for each question)
What is igneous rock?
The hot molten magma of earth chamber when comes out through an openings of the earth surface and forms hard rocks by cooling down in contact with cool air. This is called ignious rock.
What is sedimentary rock?
Different types of rocks are weathered by some natural forces and accumulate on the ocean flore. In due course of time due to the pressure of upper layer of the rocks and the heat of the earth core the sediment turn into rocks. This is called sedimentary rock.
What is metamorphic rock.
When the igneous and sedimentary rocks due to the action of different natural forces like river wind, glacier etc, converted into a new type of rocks, this is called metamorfic rock. Example—marbel.
What is fossils.
When an animal body is stored with the sediment and burried under the layer of sediment, in due course of time it solidifies and turn into rock. This animal body leaves mark on the rock. this is called fossil.
Long Questions & Answers : (3 marks for each question)
Write the features of igneous rocks.
- As the molten material solidify to form the ignec’is rocks, it is crystalized
- It has no layer.
- This types of rock does not break easily, it is comperatively hard.
- The fossil can not be found in this rock.
Write the features of the sedimentary rock.
- It has layers.
- It is soft and light.
- Sedimentary rock erodes easily,
- Fossils are found in this rock,
- This type of rock is not crystalized.
Write the charatersites of metamorphic rock.
- This rock is crystalized,
- When the sedimentary rock turns into metamorphic rock, it becomes hard.
- Fossils are not found when sedimentary rocks change into metamorphic.
- The minerals of metamorphic rocks are accumulated in one side.
What is rock cycle?
The rock cycle is the process by which rocks of one kind change into rocks of another kind. There are three main kinds of rocks: igneous rock, metamorphic rock and sedinientary rock. Each of these rocks can change in to the other kinds by physical process : cooling. melting, heating, weathering. compacting, cementing and pressure.
Write the different use of alluvial soil.
a) Alluvial soil is suitable for agriculture.
b) It is used for making idol.
c) The potter uses the soil for making pots.
d) It is used for making hut.
State the characteristics lies of different soils.
Sandy soil : i) The grains of this soil are large. 2) It can not hold more water. 3) Air can passes through this soil. 4) It is not fertile. 5) It is not fit for agriculture.
Clayey soil : i) The grains of the soil is very fine. ii) The capasity of holding air is more. iii) Air can not pass through this soil easily. iv) It can not be broken easily if it becomes dry. v) Dust clayey soil is like powder.
Loamy soil : i) It is fit for agriculter. ii) The grains of the soil is medium. iii) The ability of holding water is medium. iv) The ablity of passing air is medium.
Classify the igneous rock according to their origin.
According to their origin ignious rocks are of two types-i) Intrusive rock, ii) Extrusive rock. Intrusive rock is further divided into two types : a) Plutonie rock, b) hypabyssal rock.
When the hot molten lava of earth chamber can not reach on the earth’s surface it cools down in the earth’s chamber for many years and solidifies. This is called intrusive rock.
In the earth chamber when the magma cools down and solidifies to form a rock it is called plutonic rock. On the other hand when the magma cools down and solidifies in the crack before reaching the earth surface, this is called hypobyssal rock. Granite is the example of hypobyssal.
When the magma comes out through the crater of the volcano at the time of volcanic erruption, it cools down and solidify in contact of coal air then it is called extrusive rock. Basalt is the example of extrusive rock.
What are the differences between igneous rock and sedimentry rock.
a) Fossils can not be found in igneous rock. Fossils are found in sedimentary rocks.
b) Igneous is the rock of primery stage. Sedimentary rock is the rock of second stage.
c) Igneous rock is formed either on earth’s surface or in the earth’ chamber and sedimentary rock is formed under the ocean.
d) Ignious rock is crystalized but sedimentary rock is not crystalized.
e) There is no layer in igneous rock but layers are found in sedimentary rocks.
f) lgneous rock is hard but sedimentary rock is less hard
Why is fossil found in sedimentary rocks?
Fossil is found in sedimentary rocks because sedimentary rock is formed under the sea or lake by accumulating sediment layer by layer. then the dead body of marine plants or animals are burried at the time of accumulating sediment and solidifies to form rock. After that the mark of their bodies are left in rock layers. So the fossils are found in sedimentary rocks. As the formation of the sedimentary rocks is a long process, in the long past the fossils of the animals that appeared in different ages can be found in the sedimentary rocks and it helps us to gain knowledge about the ancient plants and animals or the climate of that ages.
Additional Questions and answers :
Mention the factors of formation of soil.
Rocks: The characteristics of a soil depend on the nature of rock(s) from which it is derived. However, soil formation is also influenced by several other factors.
Climate : Climate plays a very significant role in the formation of soil. Soil forms faster in warm and rainy climates and takes a lot of time to form in cool and dry climates. So, deeper soils are generally found in warm and humid regions.
Relief: the relief of the land influences the processes of formation of soil. Soil is unlikely to form on steep slopes. Gentler slopes support better and gradual development of soil.
Organic matter : plants and animals, alive or dead, form a very small part of soil, but are very significant. Ants, moles, earthworms and snakes loosen the soil and let air and water enter in to it. Dead remains of organisms supply nutrients to a soil.
Time : Soil does not form in a day. The natural process of soil formation may span through thousands, and sometimes, even millions of year.