Chapter - 6 Lithosphere and Land forms

 

Multiple choice questions: 

1. How much area of the Earth is covered by the hydrosphere? 

a) 61%

b) 71%

c) 81%

d) 51%

Ans. b) 71%

2. Which country of the world is known for the earthquakes?

a) India

b) France

c) Japan

d) Srilanka

Ans. c) Japan

Fill in the blanks:

1. __________ area or the Earth is surrounded by lithosphere.

Ans. 29%

2. The outer layer of the Earth is called _______.

Ans. Lithosphere

3. Sial contains silica and ________ metal mostly. 

Ans. aluminum

4. At the depth of every 32 m ______ celsius temperature increases.

Ans. 1%

Very short answer type questions:

1. Which are elementary rocks of the earth?

Ans. Igneous rocks are elementary rocks of the earth. 

2. Write names of three prominent landforms. 

Ans. Three prominent landforms are

a. Mountains

b. Plateaus

c. Plains

3. What do you call when rocks curve like waves?

Ans. Curve like waves are called folding mountains.

4. Where the volcanoes are mostly dominant in the world? 

Ans. Near the coastal areas of the Pacific Ocean and in the continental regions the volcanoes are mostly dominant in the world. 

Short answer type questions:

1. What is the difference between fold mountain and a rift mountain.?

Ans.

Fold Mountain: 

 a) The horizontal land movement in the earth causes wavelike bends in rocks such bends are called fold mountain. 
 b) In the few parts of rocks lift upward due to bending and some of them bend down.

Rift Mountain:

 a) The process of rocks breaking with pressure and tension of the horizontal land movement is called Rift mountain. 
 b) Few parts of land lift and few part go down.

2. How sedimentary rocks are formed? 

Ans. The pebbles, tiny pieces of stones, fossils which are being carried by water, air and snow are stored in layers on land or under sea bottom. such assembled substance are called sediments. These layers of sediment when under pressure and heat hardens to form sedimentary rock with layers. 

3. What is volcano? Give two causes of eruption. 

Ans. The volcano is prominent among agents which cause sudden changes on the earth. The volcano is a round hole or an open vent on the earth.

Two causes of Eruption are:

a) Volcano that erupt on Earth is due to the movements of tectonic plates. 

b) The Earth surface becomes weak with the movements of plates and the magma, pieces of rocks, ash etc. materials come out from the Earth. 

4. Mention the merits and demerits of the earthquakes. 

Ans. Merits:- 
1. Sometimes fertile land emerges.
2. Formation of new land areas.
3. Valuable minerals also come upon the surface.

Demerits:- 
1. Loss of people. People and animals perish. Buildings, railways, roads and factories suffer badly. 
2. Devastating flood occurs due to blockage of the river routes. High and devastating sea waves rise.
3. Cracks develop in lands and few areas go down due to earthquakes. 

Long answer type questions:

1. What is rock? Explain the types of rocks. 

Ans. All the substances which form the crust of earth are called rocks. The word Rock means hard material such as granite and soft material like soil both go in the formation of rocks. 

There are three types of rocks:

a) Igneous Rocks:- These rocks are the primary rocks of Earth's crust. These rocks are formed by hot molten rock material in the internal part of the earth. When this molten matter cools and hardens in and on the crust it forms a rock known as igneous rock. 

b) Sedimentary Rocks:- The pebbles, tiny pieces of stones, fossils which are being carried by water, air and snow are stored in layers on land or under sea bottom. such assembled substance are called sediments. These layers of sediment when under pressure and heat hardens to form sedimentary rock with layers. 

c) Metamorphic Rocks:- When the shape, colour and characteristic of igneous and sedimentary rocks due to internal heat and pressure completely gets changed then this completely changed rocks are called metamorphic rocks. 

2. Explain the impact of volcanoes on human life. 

Ans. The volcanoes create formations of various landforms like plains, plateaus, mountains etc. We get valuable minerals from these. The Lava which spreads all around, in the long time turns into fertile land. The dead volcanoes mouth filled with rain water creates the lakes. The volcanoes have merit and demerits too. The eruptions of volcanoes destroy human lives, cattle, vegetation, agricultural lands, houses, big cities and villages are burnt or collapse.