Rocks and Rock Cycle

Solutions for Geography, Class 9, ICSE

Analytical Questions

2 questions

Question 1

Assertion (A): Igneous rocks are called Primary rocks.

Reason (R): Igneous rocks are formed by the solidification of hot molten magma.

  1. Both A and R are true and R is the correct explanation of A.
  2. Both A and R are true and R is not the correct explanation of A.
  3. A is true but R is false.
  4. A is false but R is true.
Analytical Questions

Answer:

Both A and R are true and R is not the correct explanation of A.

Explanation — Igneous rocks are indeed called Primary rocks because they are the first type of rocks to form on Earth and serve as the parent rocks for other types. The reason that they form from the solidification of molten magma is also true. However, this process explains their formation, not specifically why they are called Primary rocks. Hence, R is not the correct explanation of A.

Question 2

Assertion (A): Metamorphic rocks do not have fossils.

Reason (R): Metamorphic rocks are formed by the change of pre-existing rocks due to high heat and pressure.

  1. Both A and R are true and R is the correct explanation of A.
  2. Both A and R are true and R is not the correct explanation of A.
  3. A is true but R is false.
  4. A is false but R is true.
Analytical Questions

Answer:

Both A and R are true and R is the correct explanation of A.

Explanation — Metamorphic rocks do not have fossils as they are formed by the change of pre-existing rocks due to high heat and pressure. Thus, the fossils of the original sedimentary rocks are destroyed.

Answer The Following Questions

18 questions

Question 1

Describe how Sedimentary Rocks and Igneous Rocks are formed. Give two examples of each.

Answer The Following Questions

Answer:

The Sedimentary rocks are formed from material derived from the pre-existing rocks and from organic sources by the process of denudation. The eroded materials brought by rivers, streams, glaciers or wind are deposited in layers to form Sedimentary rocks. For Example — Limestone, Sandstone.

Igneous rocks are formed by solidification of molten magma that comes out from an active volcano. Hence, it is also known as primary rocks. For Example — Granite, Basalt.

Question 2

On the basis of occurrence, classify Igneous Rocks.

Answer The Following Questions

Answer:

On the basis of occurrence, Igneous Rocks are of two types:

  1. Intrusive Igneous Rocks — The rocks that are formed due to solidification of magma below the Earth's surface and remains surrounded by pre-existing rock are called Intrusive Igneous Rocks.
  2. Extrusive Igneous Rocks — The rocks that are formed due to solidification of magma above the Earth's surface are called Extrusive Igneous Rocks.

Question 3

Name the three rock forming minerals.

Answer The Following Questions

Answer:

Silicates, Quartz and Feldspars are three rock forming minerals.

Question 4

What are Batholiths?

Answer The Following Questions

Answer:

Large mass of igneous rocks (chiefly composed of Granite) covering about 100 sq km area is called Batholiths. Its floor is not visible.

Question 5

What is Metamorphism? What are its causes?

Answer The Following Questions

Answer:

Alteration of the minerals and textures of a rock by changes in temperature and pressure and by a gain or loss of chemical components to such an extent that the diagnostic features of the original rocks are modified is called metamorphism.

Following are the causes of metamorphism:

  1. volcanic eruptions
  2. the mountain building movements
  3. endogenetic forces
  4. contact with undergoing water

Question 6

Name a few important characteristics of Sedimentary Rocks.

Answer The Following Questions

Answer:

A few important characteristics of Sedimentary Rocks are:

  1. The material of sedimentary rock is derived from other pre-existing rocks.
  2. They are layered rocks.
  3. Sediments are deposited in sequential order i.e. size of sediments decrease from littoral margins to the centre of the water bodies.
  4. Most of the sedimentary rocks are permeable and porous.
  5. They contain fossils.

Question 7

Name the various types of Metamorphic Rocks.

Answer The Following Questions

Answer:

The various types of metamorphic rocks are slate, schist, gneiss, quartzite, marble, amphibolite, meta-conglomerate and hornfel.

Question 8

Name the agents involved in the formation of sedimentary rocks.

Answer The Following Questions

Answer:

The agents involved in the formation of sedimentary rocks are rivers, lakes, sea, glaciers, wind and organic materials. The processes of erosion, weathering, dissolution and lithification lead to formation of sedimentary rocks.

Question 9

Give examples of metamorphic rocks formed from igneous and sedimentary rocks.

Answer The Following Questions

Answer:

Metamorphic rocks formed from igneous rocks — Gniess from granite, Schist from Basalt

Metamorphic rocks formed from sedimentary rocks — Marble from limestone, Quartzite from Sandstone.

Question 10

What are Sills and Dykes?

Answer The Following Questions

Answer:

Sills— It is sheet like body of igneous rock. It is formed when magma forces its way between two layers of sedimentary rocks and cools and solidifies there.

Dykes— It is sheet like body of intrusive igneous rock. When magma is forced upwards, it fills vertical cracks or fissures in existing rock and it hardens there to form dykes.

Question 11

Why are sedimentary rocks also called stratified rocks?

Answer The Following Questions

Answer:

Sedimentary rocks are formed by deposition of sediments in layers in beds of water bodies or on earth's surface (if brought by wind). They are deposited in layers, therefore, they are known as stratified rocks and layers are called strata.

Question 12

What processes are involved in the formation of igneous rocks?

Answer The Following Questions

Answer:

The processes involved in the formation of igneous rocks are cooling, solidification and crystallization.

Question 13

What is a Rock Cycle?

Answer The Following Questions

Answer:

A cyclic process of changing the form of rocks is called Rock cycle. It represents the interrelationships among the three rock-forming processes: igneous, sedimentary and metamorphic.

Question 14

What are the rocks?

Answer The Following Questions

Answer:

An assemblage of minerals bound together that form a more or less definite unit of the Earth's crust is called rocks.

Question 15

Classify the rocks on the basis of their origin.

Answer The Following Questions

Answer:

On the basis of their origin, rocks are of three types:

  1. Igneous rocks
  2. Sedimentary rocks
  3. Metamorphic rocks

Question 16

What is meant by intrusive rocks?

Answer The Following Questions

Answer:

Magma that solidifies below the Earth's surface and remains surrounded by the pre-existing rock is called intrusive rocks. For example, granite.

Question 17

What are extrusive rocks?

Answer The Following Questions

Answer:

The rocks that are formed due to solidification of magma on the Earth's surface are called Extrusive Igneous Rocks. For example, Obsidian.

Question 18

How important are rocks for industrial development?

Answer The Following Questions

Answer:

The importance of rocks in industrial development are:

  1. Rocks contain minerals called ores which are used for extracting metals and non-metals.
  2. They provide fossil fuels like coal and petroleum.
  3. The entire automobile industry uses petrol for their transport system.
  4. They provide raw material for manufacturing industries like limestone and gypsum are needed by cement industry.
  5. They are used as building materials. For example, granite and marble.

Choose The Correct Options

13 questions

Question 1

Which of the following rocks is also called parent rock?

  1. Sedimentary Rock
  2. Igneous Rock
  3. Metamorphic Rock
  4. None of the above
Choose The Correct Options

Answer:

Igneous Rock

Question 2

Which type of rock is Granite?

  1. Sedimentary Rock
  2. Intrusive Igneous Rock
  3. Metamorphic Rock
  4. Extrusive Igneous Rock
Choose The Correct Options

Answer:

Intrusive Igneous Rock

Question 3

Which of the following statements related to extrusive igneous rock is correct?

  1. They are formed below the earth surface
  2. They have fine crystals
  3. Limestone is the best example of this rock
  4. They are formed by the slow cooling of magma
Choose The Correct Options

Answer:

They have fine crystals

Question 4

Which of the following is the metamorphosed form of Sandstone?

  1. Slate
  2. Gneiss
  3. Quartzite
  4. Marble
Choose The Correct Options

Answer:

Quartzite

Question 5

Which of the following rocks consists of rounded; fragments, formed by cementation process?

  1. Sandstone
  2. Conglomerates
  3. Claystone
  4. Limestone
Choose The Correct Options

Answer:

Conglomerates

Question 6

Sedimentary rocks are called stratified rocks as

  1. They are formed by the accumulation of lava
  2. They are formed by the decomposition of rocks
  3. They are deposited in layers
  4. They are foliated
Choose The Correct Options

Answer:

They are deposited in layers

Question 7

Which of the following statements is correct?

  1. Igneous rocks are generally pervious in nature.
  2. Sedimentary rocks have pore spaces.
  3. Foliation is observed in igneous rocks.
  4. Fossils are found in igneous rocks.
Choose The Correct Options

Answer:

Sedimentary rocks have pore spaces.

Question 8

Which type of rock is chalk?

  1. Chemically formed sedimentary rock
  2. Carbonaceous Rocks
  3. Calcareous rocks
  4. Clastic sedimentary rock
Choose The Correct Options

Answer:

Calcareous rocks

Question 9

Which factor is responsible for the formation metamorphic rocks?

  1. Duration of daylight
  2. Heat & pressure
  3. Weathering
  4. None of the above
Choose The Correct Options

Answer:

Heat & pressure

Question 10

Which of following is the mechanically formed sedimentary rock?

  1. Limestone
  2. Dolomite
  3. Sandstone
  4. Chert
Choose The Correct Options

Answer:

Sandstone

Question 11

The cyclic process of changing the form of rocks is called

  1. Natural cycle
  2. Rock cycle
  3. Stone cycle
  4. Metamorohism
Choose The Correct Options

Answer:

Rock cycle

Question 12

Which of the following is the example of metamorphic rock?

  1. Sandstone
  2. Gneiss
  3. Chalk
  4. Granite
Choose The Correct Options

Answer:

Gneiss

Question 13

Which of the following process is responsible for the formation of igneous rocks?

  1. Sedimentation
  2. Metamorphism
  3. Cooling & solidification of magma
  4. Lithification
Choose The Correct Options

Answer:

Cooling & solidification of magma

Critical Thinking Questions

2 questions

Question 1

Rina has the hobby of collecting different stones from different areas wherever she travels. Those stones are having different colour and texture. Some are hard and some are soft. What is the reason for such difference?

Critical Thinking Questions

Answer:

The differences in colour, texture, and hardness of the stones Rina collects are due to how the rocks were formed and the minerals they contain. Since rocks are formed through various geological processes, each type has unique properties based on its origin and composition.

Question 2

Tina has been given two samples of igneous rocks. She gets a smooth feeling when touches the sample A and gets a rough feeling when she touches the sample B. How can she understand whether sample A and B are extrusive or intrusive igneous rock?

Critical Thinking Questions

Answer:

Sample A is Extrusive and sample B is intrusive igneous rock.

Reason: Extrusive igneous rocks cool quickly on the Earth's surface, resulting in fine-grained, smooth textures. In contrast, intrusive igneous rocks cool slowly beneath the surface, allowing larger crystals to form, which gives them a rougher texture.

Define The Following Terms

5 questions

Question 1

Minerals

Define The Following Terms

Answer:

Minerals are naturally occuring, homogenous solid inorganic substance that has a definite chemical composition with its own chemical and physical properties.

Question 2

Rocks

Define The Following Terms

Answer:

Rock can be defined as an aggregate of minerals that form a more or less definite unit of the earth's crust.

Question 3

Sills

Define The Following Terms

Answer:

A sheet like body of igneous rock that is formed when magma forces its way between two layers of sedimentary rocks and cools and solidifies there is called Sills.

Question 4

Dykes

Define The Following Terms

Answer:

A sheet like body of intrusive igneous rock which is formed when magma is forced upwards, it fills vertical cracks or fissures in existing rock is called Dykes.

Question 5

Conglomerate

Define The Following Terms

Answer:

Conglomerate is a type of mechanically formed sedimentary rock which consists of rounded or sub-rounded fragments, usually water-born cobbles, pebble and gravel, cemented together by a matrix of calcium carbonate, silica, etc.

Diagram

2 questions

Question 1

Draw a diagram of a volcano and igneous rocks.

Diagram

Answer:

Below diagram shows a volcano and igneous rocks:

Draw a diagram of a volcano and igneous rocks. Rocks and Rock Cycle, Geography by Veena Bhargava Goyal Brothers Prakashan Solutions ICSE Class 9.

Question 2

Draw a neat diagram to show the rock cycle.

Diagram

Answer:

Below diagram shows the rock cycle:

Draw a neat diagram to show the rock cycle. Rocks and Rock Cycle, Geography by Veena Bhargava Goyal Brothers Prakashan Solutions ICSE Class 9.

Distinguish Between The Following Terms

3 questions

Question 1

Rocks and Minerals

Distinguish Between The Following Terms

Answer:

S.
No.
RocksMinerals
1.Rocks are aggregates of mineral elements.Minerals are naturally occuring solid inorganic substances.
2.Rocks are heterogeneous in their composition.Minerals are homogeneous in form.
3.A rock has no definite chemical composition.Minerals have a definite chemical composition.
4.On the basis of origin, rocks are igneous, sedimentary and metamorphic.Four chief mineral groups are silicates, carbonates, sulphides and metallic minerals.
5.Other important types of rocks are basalt, granite, sandstone, slate and quartz.Other important minerals are iron, silicon, magnesium, nickel, calcium, potassium, etc.

Question 2

Volcanic rocks and plutonic rocks

Distinguish Between The Following Terms

Answer:

S.
No.
Volcanic rocksPlutonic rocks
1.They are also called extrusive rocks.They are also called intrusive rocks.
2.They are formed when magma solidifies on the surface of earth.They are formed when magma solidifies within the earth's crust.
3.They are smooth, crystalline and fine grained.They are coarse textured, hard rocks with large crystals.
4.For example- basaltFor example- granite

Question 3

Thermal and Dynamic Metamorphism

Distinguish Between The Following Terms

Answer:

S.
No.
Thermal MetamorphismDynamic Metamorphism
1.It occurs when rocks are formed due to high temperature.It occurs when rocks are formed due to high pressure.
2.For example- slate is formed from clay.For example- marbles are formed from Dolomites.

Give Reasons For The Following

5 questions

Question 1

Igneous rocks are also called primary rocks.

Give Reasons For The Following

Answer:

Igneous rocks are also called primary rocks because they are formed when molten lava solidifies. Sedimentary rocks and metamorphic rocks are formed from other rocks.

Question 2

Extrusive igneous rocks have generally small crystals.

Give Reasons For The Following

Answer:

Extrusive igneous rocks have generally small crystals because they cool rapidly to solidify. The crystals do not have much time to form until the rock cools all the way, which stops the crystal growth.

Question 3

Rocks are of great economic significance.

Give Reasons For The Following

Answer:

Rocks are of great economic significance because they provide us with various minerals, fossil fuels, building materials and precious metals etc.

Question 4

Lithosphere is called rocksphere.

Give Reasons For The Following

Answer:

The Lithosphere is the outermost layer of the Earth's crust that is made up of solid rocks, including igneous and sedimentary rocks. In Greek, Litho means rock or stone. Thus, Lithosphere is also called rocksphere.

Question 5

No fossil is found in metamorphic rock.

Give Reasons For The Following

Answer:

Metamorphic rocks are formed due to change in texture and mineral composition of the pre-existing rocks. During this process of change, the fossils of original sedimentary rocks are destroyed and therefore no fossil is found in metamorphic rocks.