I. Choose the correct answer
Question 1.
Which of the following is known as sphere of rocks –
(a) Atmosphere
(b) Biosphere
(c) Lithosphere
(d) Hydrosphere
Answer:
(c) Lithosphere
Question 2.
World soil day is observed on –
(a) 15th August
(b) 12th January
(c) 15th October
(d) 5th December
Answer:
(d) 5th December
Question 3.
Fossils are found in –
(a) Sedimentary rocks
(b) Igneous rocks
(c) Metamorphic rocks
(d) Plutonic rocks
Answer:
(a) Sedimentary rocks
Question 4.
The first layer of soil is called as –
(a) Regur
(b) Regolith
(c) Unweathered rock
(d) Partially weathered rock
Answer:
(*) Horizon
Question 5.
Ideal soil for growing cotton is –
(a) Red soil
(b) Black soil
(c) Alluvial soil
(d) Mountain soil
Answer:
(b) Black soil
Question 6.
The major component of soil is –
(a) Rocks
(b) Gas
(C) Water
(d) Minerals
Answer:
(d) Minerals
Question 7.
Which one of the following is the most widespread most and’productive category of soil –
(a) Alluvial soil
(b) Black soil
(c) Red soil
(d) Mountain soil
Answer:
(a) Alluvial soil
II. Fill in the Blanks
Answer:
III. State whether the following statements are true or false
Question 1.
Igneous rocks are called primary rocks.
Answer:
True
Question 2.
Slate is formed from shale.
Answer:
True
Question 3.
Red soil is formed by the process of leaching.
Answer:
False
Correct statement:
Laterites soils i s formed by the process of leaching.
Samacheer Kalvi 8th Social Guide Rock And Soil Question 4.
M – sand is used as alternative for natural sand in construction.
Answer:
True
Question 5.
Volcanic mountains are covered with sedimentary rocks.
Answer:
False
Correct statement:
Sedimentary rocks are formed from broken pieces of rocks.
IV. Match the following
Question 1.
a. 2
b. 1
c. 4
d. 3.
Question 2
Answer:
a. 2
b. 4
c. 1
d. 3.
V. Choose the incorrect statement from the following
Question 1.
Answer:
3. Sedimentary rocks are the hardest ones.
Question 2.
Answer:
2. Dynamic metamorphism is caused by high temperature.
VI. Consider the following statements and choose the right option from the given ones
Statement (1) – Sedimentary rocks consist of many layers.
Statement (2) – Sedimentary rocks are formed by the sediments deposited at different points of time.
Answer:
1. 1 and 2 are correct and 2 explains 1
VII. Give reasons for the following
Question 1.
Chemical sedimentary rocks are found in the beds of reservoirs.
Answer:
Chemical Sedimentary rocks are formed by precipitating of minerals from water. It is formed usually through evaporation of chemical rich solutions.
Question 2.
Igneous rocks are found in the regions of volcanoes.
Answer:
The igneous rocks are formed by the solidification of molten magma.
VIII. Distinguish the following
Question 1.
Metamorphic rock and sedimentary rock.
Answer:
Metamorphic Rocks:
Sedimentary Rocks:
Question 2.
Soil conservation and Soil erosion.
Answer:
Soil conservation:
Soil erosion:
IX. Give short answers
Question 1.
How are igneous rocks formed?
Answer:
The igneous rocks are formed by the solidification of molten magma.
Question 2.
Describe about the composition of soil.
Answer:
The basic components of soil are mineral, organic matter, water and air. It consists of about 45% mineral, 5% organic matter, 25% of water and 25% air. It is only a generalized fact. The composition of soil varies from place to place and time to time.
Question 3.
Define ‘rock’.
Answer:
Question 4.
State the types of soils.
Answer:
Alluvial soil, Black soil, Red soil, Laterite soil, Mountain soil, Desert soil.
Question 5.
What is soil conservation?
Answer:
Soil conservation is the process of protecting the soil from erosion to maintain its fertility.
X. Give detailed answer for the following
Question 1.
Explain the process of soil formation.
Answer:
Question 2.
Classify and explain the rocks.
Answer:
Igneous:
(i) The igneous rocks are formed by the solidification of molten magma. Also called Primary or Parent Rocks.
(ii) Types:
1. Extrusive Igneous Rocks:
Molten magma which comes out from the interior of the earth’s surface, gets solidified and forms such rocks. Fine grained and glassy in nature. Eg., Basalt, found in north western peninsular India.
2. Intrusive Igneous rocks:
Molten magma cools down deep inside the earth’s crust, becomes solid and forms such rocks. Form large grains. Deep seated rocks are plutonic rock and ones at shallow depths – Hypabysal rocks. Example Granite, Diorite.
Sedimentary:
(i) Formed by the sediments derived and deposited by various agents. Also called stratified rocks.
(ii) Types:
1. Organic sedimentary rocks:
Formed due to decomposition of dead Plants and Animals. Contains fossils. Example Chalk, Talc
2. Mechanical sedimentary rocks:
Formed from the disintegration of Igneous and metamorphic rocks. Get deposited due to erosion by natural agents. Get cemented after a long time to form rocks. Example Sandstone, Shale.
3. Chemical sedimentary rocks: Formed by precipitating of minerals from water. Formed due to evaporation of chemical rich solution. Example Rock Salt.
Metamorphic:
(i) Formed when Igneous and sedimentary rocks are subjected to high temperature and pressure.
(ii) Types:
1. Thermal Metamorphic:
If the change in rocks is caused by high temperature.
2. Dynamic Metamorphic:
If the change in rock is caused by high pressure. Formed from Igneous rocks. Eg., Granite into gneiss
Formed from Sedimentary rocks. Eg., Shale into Slate
Question 3.
Give an account on different layers of soil.
Answer:
Question 4.
Classify and explain the soil.
Answer:
Definition:
Soil is a mixture of Organic matter, minerals, gases, liquids and organisms that together support life.
Classification of soils:
Soils are classified on the basis of their formation, colour, physical and chemical properties. Based on these, soil is classified into six major types. They are: Alluvial soil, Black soil, Red soil, Laterite soil, Mountain soil, Desert soil.
Alluvial soil:
Black soils:
Red Soils:
Laterite soils:
Mountain soils:
Desert soils:
IX. Activity Corner
Question 1.
Complete the following table with the help of internet source
Answer:
Question 2.
Map Work:
Mark the areas of black soil on the outline map of India.
Answer:
Additional Questions
I. Choose the correct answer
Question 1.
……………. rocks are also called Primary rocks.
(a) Sedimentary
(b) Igneous
(c) Metamorphic
(d) Stratified
Answer:
(b) Igneous
Question 2.
…………….. rocks are also known as stratified rocks.
(a) Igneous
(b) Metamorphic
(c) Sedimentary
(d) Hypabysal
Answer:
(c) Sedimentary
Question 3.
Oldest sedimentary rocks of the world have been identified in
(a) Green land
(b) India
(c) France
(d) Australia
Answer:
(a) Creen landi
Question 4.
…………….. soil is suitable for milled cultivation.
(a) Alluvial
(b) Black
(c) Latente
(d) Red
Answer:
(d) Red
Question 5.
……………. soil is porous and saline.
(a) Mountain
(b) Desert
(c) Alluvial
(d) Red
Answer:
(b) Deserti
Question 6.
The time needed to form soil depends on the ……………..
(a) altitude
(b) rainfall
(c) climate
(d) fertility
Answer:
(c) climate
II. Fill in the blanks
Answer:
III. Match the following
a. iiii
b. iv
c. i
d. ii
IV. Choose the incorrect statement from the following
Question 1.
Answer:
4. Laterite soil is thin and acidic
V. Consider the following statement and choose the right option from the given ones
Question 1.
Statement (1) :
Proper management of soil resource will lead to sustainable food production.
Statement (2) :
India is an Agricultural country.
Answer:
3. 1 and 2 are correct and 2 explains 1
VI. Give Reason for the following
Question 1.
The Laterite soil is infertile.
Answer:
Laterite are the typical soils of trophical regions. These soils are found in the regions which experienced alternate wet and dry condition. As these soils are formed by the process of leaching, it is in fertile.
Question 2.
Sedimentary rocks are called stratified rocks.
Answer:
Sedimentary rocks consist of many layers which were formed by the sediments deposited at different periods. As it consists of many strata, it is also known as ‘Stratified rocks’.
VII. Distinguish the following
Question 1.
Igneous rock and sedimentary rock.
Answer:
Igneous rocks:
Sedimentary rocks:
VIII. Give short answers
Question 1.
Name the four realms of earth.
Answer:
Four realms of the earth, are lithosphere, hydrosphere, atmosphere and biosphere.
Question 2.
What is the Lithosphere composed of?
Answer:
Lithosphere is composed of solid rocks and unconsolidated materials.
Question 3.
What is lava?
Answer:
Lava is actually a fiery red molten magma comes out from the interior of the earth on its surface.
Question 4.
Why are crystalline rocks called so?
Answer:
The intrusive Igneous rocks consist of large crystals, and so they are also called as ‘Crystalline rocks’.
Question 5.
Name a few Major Active Volcanoes.
Answer:
Major Active Volcanoes:
Mount Vesuvius, Mt. Stromboli and Mt. Etna in Italy and Mauna Loa and Mauna Kea in Hawaii Islands.
Question 6.
What are the characteristics of Sedimentary rocks?
Answer:
Question 7.
What is Thermal Metamorphism?
Answer:
If the change in the rocks is mainly caused by high temperature, the process is called as thermal metamorphism..
Question 8.
Explain Dynamic Metamorphism.
Answer:
If the change in the rock is mainly caused by high pressure, the process is called as Dynamic Metamorphism.
Question 9.
State the characteristics of Metamorphic rocks.
Answer:
Question 10.
Mention some uses of rocks.
Answer:
IX. Give Detailed Answer
Question 1.
Explain the different types of sedimentary rocks.
Answer:
Types of Sedimentary Rocks
1. Organic Sedimentary Rocks:
2. Mechanical Sedimentary Rocks:
3. Chemical Sedimentary rocks
Question 2.
Explain the Rock cycle with a diagram.
Answer:
1. Igneous rocks are the primary rocks formed first on the earth. These rocks are weathered, eroded, transported and deposited at some places to form sedimentary rocks.
2. The Igneous and Sedimentary rocks are changed into metamorphic rocks under the influence of temperature and pressure.
3. The metamorphic rocks are also get disintegrated and deposited to form sedimentary rocks.
4. Formation of igneous rocks take place when there is an outflow of molten materials. Like this, the rocks of the earth crust keeps on changing from one form to another form under various natural forces and agents.
5. The endless process is referred as Rock Cycle.
Question 3.
Mention the uses of soils.
Answer:
Uses of soils:
Soil is one of the important natural resource. It is a basic requirement for plant growth and supports various life forms on the earth.