Rocks and soils Book Back Questions 8th Social Science Lesson 9

8th Social Science Lesson 9

9] Rocks and soils

Book Back Questions with Answer and Do You Know Box Content

Do You Know?

Petrology is a branch of geology which deals with the study of rocks. “Petrology” is derived from the Greek word “Petrus” refers to rock and “Logos” refers to study.

The word Igneous is derived from the Latin word “Ignis” means “fire”.

Some major Active Volcanoes: Mount Vesuvius, Mt. Stromboli and Mt. Etna in Italy and Mauna Loa and Mauna Kea in Hawaii Islands.

Oldest sedimentary rocks of the world have been indentified in Greenland and estimated as 3.9 billion years old.

Sedimentary rocks are the important source of natural resources like coal, oil and natural gas.

One of the world wonders Taj Mahal in India was built with White Marbles a metamorphic rock.

Quartzite and Marble are the rocks commonly used for construction and sculpture works. Marbles are widely used for making beautiful statues and decorative items such as vase, tiny gift articles and grinded marble is used to produce plastics, paper etc.,

World Soil Day is observed on 5^th December, every year.

How long does it take to form soil? The time needed to form a soil depends on the Climate. The environments which are characterized by mild climate, takes 200-400 years to form one cm of soil and in wet tropical area, soil formation is faster and takes upto 200 years. To become a well matured soil, it takes about 3000 years.

Choose the best answers:

1. Which of the following is known as sphere of rocks?

(a) Atmosphere

(b) Biosphere

(c) Lithosphere

(d) Hydrosphere

2. World soil day is observed on

(a) 15^th August

(b) 12^th January

(c) 15^th October

(d) 5^th December

3. Fossils are found in

(a) Sedimentary rocks

(b) Igneous rocks

(c) Metamorphic rocks

(d) Plutonic rocks

4. The top layer of soil is called as

(a) Organic layer or humas

(b) Topsoil

(c) Subsoil

(d) Bedrock

5. Ideal soil for growing cotton is

(a) Red soil

(b) Black soil

(c) Alluvial soil

(d) Mountain soil

6. The major components of soil is

(a) Rocks

(b) Minerals

(c) Water

(d) All the above

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

Fill in the blanks:

1. Scientific study of rocks is called ____________

2. _________ soil is highly suitable for millets cultivation.

3. The “skin of earth” is ___________

4. ____________ is the kind of metamorphic rock using which Taj Mahal was built.

5. ___________ is known as the primary rocks.

State true or false. If false, correct the statement:

1. Igneous rocks are called primary rocks.

2. Slate is formed from shale.

3. Red soil is formed by the process of leaching.

4. M-sand is used as alternative for natural sand in construction.

5. Volcanic mountains are covered with sedimentary rocks.

Match the following:

(a)

1. Granite – (a) Bed rock

2. Soil layer – (b) Plutonic rock

3. Barren island – (c) Strip farming

4. Soil conservation – (d) Active Volcano

a b c d

(a) 2 1 4 3

(b) 2 1 3 4

(c) 4 3 2 1

(d) 3 4 2 1

(b)

a. Basalt – 1. Anthracite

b. Limestone – 2. Extrusive igneous

c. Coal – 3. Metamorphic rock

d. Gneiss – 4. Sedimentary rock

a b c d

(a) 2 4 3 1

(b) 2 4 1 3

(c) 3 1 2 4

(d) 3 1 4 2

Consider the following the statements and tick the appropriate answer:

1. a) Igneous rocks are called the primary rocks.

b) Soil is the product of weathering of rocks.

c) Sedimentary rocks are the hardest ones.

d) Deccan plateau is the region of Igneous rocks.

2. a) Soil erosion decreases its fertility.

b) Dynamic metamorphism is caused by high temperature.

c) Soil is a renewable source.

d) Humus is a part of the top layer of soil.

Consider the following the statements and tick the appropriate answer:

1. Statement (1): Sedimentary rocks consist of many layers.

Statement (2): Sedimentary rocks are formed by the sediments deposited at different points of time.

(a) 1 and 2 are correct and 2 explains 1

(b) 1 and 2 are correct but, 2 does not explain 1

(c) 1 is correct but, 2 is incorrect

(d) 2 is correct but, 1 is incorrect

Answers:

Choose the best answers:

1. Lithosphere 2. 5th December 3. Sedimentary rocks 4. Organic layer or humas 5. Black soil 6. Minerals 7. Alluvial soil

Fill in the blanks:

1. Petrology 2. Black 3. Soil 4. White Marble 5. Igneous rocks

State true or false. If false, correct the statement:

1.True

2.True

3.False

Correct answer: Laterite soil is formed by the process of Leeching

4.True

5.False

Correct answer: Volcanic mountains are covered with Igneous rocks

Match the following:

1. 2 1 4 3
2. 2 4 3 1

Choose the incorrect statement from the following

1.Sedimentary rocks are the hardest ones

2.Soil is a renewable source

Consider the statements given below and choose the correct option:

• 1. and 2 are correct and 2 explains 1