Class 11 Geography Chapter 8 Composition and Structure of Atmosphere

Class 11 Geography Chapter 8 Composition and Structure of Atmosphere The answer to each chapter is provided in the list so that you can easily browse throughout different chapters SCERT Class 11 Geography Chapter 8 Composition and Structure of Atmosphere and select need one.

Class 11 Geography Chapter 8 Composition and Structure of Atmosphere

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Also, you can read the SCERT book online in these sections Solutions by Expert Teachers as per SCERT (CBSE) Book guidelines. These solutions are part of SCERT All Subject Solutions. Here we have given Assam Board/NCERT Class 11 Geography Chapter 8 Composition and Structure of Atmosphere Solutions for All Subject, You can practice these here…

Composition and Structure of Atmosphere

Chapter: 8

PART-1

GEOGRAPHY

TEXTUAL QUESTION & ANSWER

Q.1. Which one of the following gases constitutes the major portion of the atmosphere? 

(i) Oxygen

(ii) Nitrogen

(iii) Argon

(iv) Carbon- di- oxide

Ans: (ii) Nitrogen

Q.2. Atmospheric layer important for human beings is 

(i) Stratosphere

(ii) Mesosphere 

(iii) Troposphere

(iv) Ionosphere 

Ans: (iii) Troposphere

Q.3. Sea, salt, pollen, ash, smoke, soot, fine soil-these are associated with- 

(i) Gases

(ii) Dust particles

(iii) Water vapour

(iv) Meteors

Ans: (ii) Dust particles

Q.4. Oxygen gas is in negligible quantity at the height of atmosphere-

(i) 90km.

(ii) 120km.

(iii) 100km.

(iv) 150km.

Ans: (ii) 120km.

Q.5. Which one of the following gases is transparent to incoming solar radiation and opaque to outgoing terrestrial radiation? 

(i) Oxygen

(ii) Nitrogen

(iii) Helium 

(iv) Carbon Dioxide

Ans: (iv) Carbon Dioxide

(b) Answer the following questions in about 30 words:

Q.1. What do you understand by atmosphere? 

Ans: Atmosphere is a vast expanse of air which envelopes the earth all round. It is a mixture of different gases. Atmosphere contains life giving gases like oxygen for humans and animals and carbon dioxide for plants. Without air or atmosphere no life can survive.

Q.2. What are the elements of weather and climate? 

Ans: The main elements of weather and climate are: 

(a) Temperature

(b) Pressure

(c) Humidity

(d) Winds

(e) Clouds

(f) Precipitation.

Q.3. Describe the composition of atmosphere.

Ans: The atmosphere is composed of various gases, water vapour and dust particles. The proportion of the composition changes in different parts of the atmosphere. For example oxygen will be almost negligible at the height of 120km. Carbon dioxide and water vapour are found only up to 90km from the surface of the earth. The various gases and their volume are given in the following table.

Q.4. Why is the Troposphere the most important of all the layers of the atmosphere? 

Ans: Troposphere is the most important layer of all the layers of the atmosphere due to the following reasons,

1. It contains all the gases which are essential for living beings.

2. All the weather phenomena take place in this layer.

3. It is the layer where precipitation, clouds, water vapour are found.

4. At different altitudes, different weather and climatic phenomena are observed in this layer of the atmosphere.

(c) Answer the following questions in about 150 words.

Q.1. Draw a suitable diagram for the structure of the atmosphere and label it and describe it.

Ans: The atmosphere consists of different layers with varying density and temperature. Density is highest near the surface of the earth and decreases with increasing altitude. Depending upon the temperature conditions the earth’s atmosphere is divided into five different layers.

They are:

(a) Troposphere 

(b) Stratosphere

(c) Mesosphere

(d) Thermosphere

(e) Exosphere

(a) Troposphere: The troposphere is the lowermost layer of the atmosphere. It’s average height is 13 km and expands roughly to a height of 8km near the poles and about 18 km. All changes in climate and weather take in this layer. The temperature in this layer decreases at the rate 1°C for every 165m of height (6.4°C for every 1000m.) Above the troposphere layer there is a small zone which is known as the troposphere.

(b) Stratosphere: Stratosphere layer is found above the tropopause and extends up to a height of 50 km. This layer contains maximum ozone, which absorbs ultraviolet radiation and saves the living being from intense, harmful form of energy.

(c) Mesosphere: The layer mesosphere lies above the stratosphere, which extends up to a height of 80km. In this layer temperature starts decreasing with increasing height and height and reaches up to minus 100°C at the height of 80km. The upper limit of Mesosphere is called as menopause.

(d) Thermosphere or Exosphere:This layer is located between 80 and 400km. It contains electrically charged particles known as ions and hence it is known as ionosphere. Radio waves transmitted from the earth are reflected back to the earth by this layer.

(e) Exosphere: Exosphere is the uppermost layer which is located above the ionosphere. About this layer, very little is known. Whatever contents are these are extremely rarefied in this layer and it gradually merges with the outer space.

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