RBSE Class 11 Geography Important Questions Chapter 8 Composition and Structure of Atmosphere

Rajasthan Board RBSE Class 11 Geography Important Questions Chapter 8 Composition and Structure of Atmosphere Important Questions and Answers. 

RBSE Class 11 Geography Important Questions Chapter 8 Composition and Structure of Atmosphere 

Multiple Choice Questions

1. What is necessary for human life?
(A) Nitrogen 
(B) Oxygen
(C) Argon 
(D) Ozone.
Answers:
(B) Oxygen

 

2. What is the essential gas for plants?
(A) Oxygen 
(B) Argon
(C) Ozone
(D) Carbon dioxide.
Answers:
(D) Carbon dioxide.

3. What is the amount of nitrogen gas in the atmosphere?
(A) 78.08% 
(B) 74.08%
(Q 72.08% 
(D) 76.08%.
Answers:
(A) 78.08% 

4. What is the speed of light?
(A) 3 lakh kilometres per second
(B) 5000 k.m. per second
(C) 10 k.m. per second
(D) 100 k.m. per second.
Answers:
(A) 3 lakh kilometres per second

5. The lowest layer of atmosphere is-
(A) Mesosphere 
(B) Ionosphere
(C) Troposphere 
(D) Exosphere.
Answers:
(C) Troposphere 

6. At which height, Oxygen is negligible?
(A) 100 km 
(B) 110 km
(C) 120 km 
(D) 130 km.
Answers:
(C) 120 km 

7. How much % of oxygen is in atomphere?
(A) 15.93% 
(B) 17.95%
(C) 20.95% 
(D) 25.95%.
Answers:
(C) 20.95% 

8. Which gas absorbs solar rays?
(A) Oxygen 
(B) Argon
(C) Ozone 
(D) Carbon Dioxide.
Answers:
(D) Carbon Dioxide.

9. Which is a green house gas?
(A) Carbondioxide 
(B) Ozone
(C) Oxygen 
(D) Nitrogen.
Answers:
(A) Carbondioxide 

10. Which gas absorbs ultra violet rays of the sun?
(A) Ozone 
(B) Oxygen
(C) Nitrogen 
(D) Argon.
Answers:
(A) Ozone 
 
Very Short Answer Type Questions

Question 1. 
What is atmosphere?
Answer: 
An envelope of gases around the earth.

Question 2.
Which are the two major gases constituting the atmosphere?
Answer: 
Nitrogen and oxygen.

Question 3. 
What is the percentage of nitrogen gas present in atmosphere?
Answer: 
78%.

Question 4. 
What is the percentage of oxygen gas present in the atmosphere?
Answer: 
21%.

Question 5. 
Why is atmosphere held to the earth?
Answer: 
Due to force of gravity.

Question 6.
Name two gases found in the upper layers of atmosphere.
Answer: 
Argon, Helium.

Question 7. 
Which rays are absorbed by ozone gas?
Answer: 
Ultra-violet rays of the sun.

Question 8. 
Which is the weather making layer of atmosphere?
Answer: 
Troposphere.

Question 9. 
What is the normal lapse rate of temperature?
Answer: 
1°C for 165 metres.

Question 10. 
Which is the boundary between troposphere and stratosphere?
Answer: 
Troposphere.

Question 11. 
Which layer of atmosphere is called thermosphere?
Answer: 
Stratosphere (Due to constant temperatures).

Question 12. 
When has been a hole in ozone layer noticed?
Answer: 
In 1980, a hole in ozone layer on Antarctica.

Question 13. 
What are the two harmful effects of ozone gas?
Answer: 
Skin cancer and Blindness.

Question 14. 
What is the use of Ionosphere?
Answer: 
It reflects the radio waves back to the earth.

Question 15. 
What are the two causes of depletion of ozone layer?
Answer: 
Use of carbons (industrialisation) and Deforestation.

Question 16. 
What is the function of dust particles in atmosphere?
Answer: 
These cause fog, clouds and absorb insolation.

Question 17. 
Name the town from where Indian daily weather maps are published.
Answer: 
Pune.

Question 18. 
Name the science which studies the atmospheric conditions.
Answer: 
Meteorology.

Question 19. 
Which is the coldest layer of the atmosphere?
Answer: 
Mesosphere.
   
Short Answer Type Questions

Question 1. 
Name the main elements of atmosphere. 
Answer: 

1. Gases 
2. Dust particles 
3. Water vapour. 

Question 2. 
Name the different layers of atmosphere. 
Answer: 

1. The troposphere-the lowest layer
2. The stratosphere-layer next to troposphere
3. Ozonesphere-zone of ozone gas
4. Ionosphere-zone of ion gas
5. Exosphere-the uppermost layer.

Question 3. 
Define the climate of a place. How do you determine it?
Answer: 
Climate is the average weather of a place over a long period of time. Climate is the composite picture of the daily weather. Climate is everlasting and does not change often. It is similar year after year. Studies of climate are based on the data relating to the last 3-40 years. It is the average of climatic conditions of an area over a long period.

Question 4. 
Name the elements of weather.
Answer: 
The atmospheric conditions which make up the weather of place are known as elements of weather. These are :

1. Temperature 
2. Pressure 
3. Winds 
4. Sunshine 
5. Humidity 
6. Cloudiness 
7. Rainfall 
8. Mist and fog.

Question 5. 
Name the major controls of climate.
Answer: 
The factors which change the climate from place to place are known as the elements of climate.

1. Latitude 
2. Altitude 
3. Distribution of land and water 
4. Pressure
5. Prevailing winds 
6. Ocean currents 
7. Mountain barriers.

Question 6. 
‘Water vapour acts like a Blanket.’ Discuss.
Answer: 
Water vapour also decreases from the equator towards the poles. Water vapour absorbs parts of the insolation from the sun, and thus, reducing its amount reaching the earth’s surface. It also preserves the earth’s radiated heat. It thus, acts like a blanket  allowing the earth neither to become too cold nor too hot. Conditions of stability and instability in the air are greatly influenced by the role of water vapour.

Question 7. 
Explain the importance of ozone gas.
Answer: 
The ozonosphere extends between 10-50 km. above the surface of earth. It acts as a filter and absorbs the ultra violet rays radiating from the sun. These rays do not reach the earth. It shields the life on the earth from intense, harmful form of energy.

Question 8. 
The atmosphere acts as a blanket or a glass-house. Discuss.
Answer: 
Atmosphere acts like a blanket keeping the earth warm. It absorbs incoming solar radiation and does not allow radiation to escape.

Question 9. 
Atmosphere is the most dynamic element in environment. Discuss.
Answer: 
Atmosphere keeps on changing day and night. So the weather changes day to day. Great contrasts are found in day and night temperatures clouds change wind velocity.
Answer: 

1. Atmosphere makes the earth habitable.
2. It contains life-giving gases like oxygen and nitrogen for animal and plant life.
3. It is the storehouse of water vapour which leads to precipitation.
4. It protects us from millions of falling meteors.
5. It absorbs ultra-violet rays.
6. It acts as an air conditioner by moderating the extremes of heat and cold.

Question 11. 
(a) Write a note on ozone layer of the atmosphere.
(b) Why is it depleting? Where has been a hole in this layer found?
(c) What are its harmful effects?
Answer: 
Ozone Layer. A thick layer of ozone gas exists in upper atmosphere. This layer is useful as it absorbs ultra-violet rays of the sun. Due to excessive use of chemicals and carbons, (which react with Ozone layer), the ozone layer is being depleted. The atomic explosions also deplete the ozone layer. In 1980, a hole in the ozone layer was noticed over Antarctica. Through this hole, ultra-violet rays will reach the earth. These rays are harmful as these cause skin cancer. It may cause blindness.

Question 12. 
Name the main constituents of the pure dry air.
Answer: 
The atmosphere mainly consists of three elements :

1. Gases 
2. Water vapour 
3. Dust particles. 

About 99% of the atmosphere consists of two gases.
(a) Nitrogen-78%
(b) Oxygen-21%
The remaining 1% is composed of a number of gases like hydrogen, argon, ozone, helium, carbon dioxide.

Question 13. 
Define Atmosphere. (TBQ)
Answer: 
Atmosphere is a vast expanse of air which envelopes the earth all around. It represents the gaseous realm of the earth. It is held to the earth by the force of gravity. It is, thus, an integral part of the earth. It is a very vital part of human existence on the earth.

Question 14. 
What is tropopause?
Answer: 
Tropopause is the imaginary plane which separates the stratosphere from Troposphere. It is the boundary between the two layers of atmosphere. It is known as ‘the ceiling of the troposphere’ as it is the upper layer of troposphere. Actually, it is a thin ‘transitional zone’ between the two layers.

Question 15. 
Describe the role of water vapour in the weather processes.
Answer: 
Water Vapour. Water vapour is the result of evaporation from water bodies on the earth. Water vapour represents about 2 per cent of the air by volume. The presence of water vapour in the atmosphere is of primary importance in weather phenomena.

1. It reduces the amount of insolation reaching the earth’s surface by absorption.
2. It acts like an insulating blanket by preserving the earth radiation. It allows the earth neither to become too cold nor too hot.
3. Water vapour is the basic cause of all condensation and precipitation.
4. Water vapour condenses into clouds and fogs.
5. ater vapour is the main source of energy giving rise to cyclones, storms, etc.
6. Water vapour both releases and consumes latent heat of condensation which cools and warms the air.
7. Water vapour makes the air stable and unstable.

Question 16. 
Why is the height of troposphere the greatest at the equator?
Answer: 
The height of troposphere varies from one place to another. It is 8 kms. at the poles and 20 kms. at the equator. The equator receives the maximum amount of insolation. The heated surface gives rise to strong convection currents. These currents transport the heat to great heights. The light air rises and increases the zone of troposphere. In other areas, due to low temperatures, descending winds reduce the height of the troposphere.
 
Essay Type Questions

Question 1. 
Explain the Importance of the Atmosphere.
Answer: 
The atmosphere is useful for man in the following fields :
1. Basis of Life. Atmosphere is the very basis of life on the earth. We cannot even imagine life without atmosphere. Atmosphere contains oxygen which is very essential for human existence and carbon dioxide is useful for vegetation. The earth is the only planet having atmosphere.

2. Weather. Weather has a great influence on our life. Evaporation, precipitation, winds, etc., take place due to atmosphere.

3. Heat Balance. Atmosphere acts as a green house for us. The ‘Green House’ effect keeps earth’s temperature at an average of 35°C. Without atmosphere, under extremes of temperature life would have been impossible.

4. Harmful Radiations. A layer of ozone gas absorbs the ultraviolet radiations coming from the sun. The ozone, layer, thus protects the earth from ultraviolet radiations.

5. Radio Broadcasting. Ionosphere layer of the atmosphere reflects the radio waves transmitted from the earth and sends them back to earth. This helps in radio-broadcasting.

6. Safeguard against Meteorites. Meteorites are constantly falling from outer space towards the earth. Most of these are burnt in atmosphere.

7. Aviation. Aeroplanes fly in this medium of atmosphere. Jet planes fly in stratosphere (upper layers).

Question 2. 
Explain, with examples, the difference between weather and climate.
Answer: 
The term ‘weather’ should not be confused with ‘climate’ though they are very closely related to each other in the study of meteorology and climatology. Weather. Weather is the sum total of atmospheric conditions at any place at any specific time. The weather changes from day-to-day, and hour-to-hour. We often speak of hot ‘weather’, ‘windy’ weather, a cold morning, ‘a sunny afternoon’ etc. Weather stands for the atmospheric conditions for a short period for a day, a week or a month.

That is the reason why the All India Radio broadcasts the weather conditions. The Indian Meteorological Department publishes the daily Indian Weather Maps. In Britain, the weather is so changing that it is often said, “Britain has no climate, only weather.” It has been said that climate is what you expect, but weather is what you get. 

Climate. Climate is the description of atmospheric conditions of an area over a long period (say 35 years). Thus climate is the average weather of a place over a long period of time. Studies of Indian climate are based on the data relating to the last 100 years. Climate is the composite picture of the changing daily weather conditions. Egypt experiences similar weather day-to-day and it is said, “Egypt has no weather, only climate.”

The basic difference between weather and climate is that weather refers to a short period while the climate refers to a much longer period. We may speak of warm weather of a particular day, but not of a warm climate for that particular day.

Differences between Weather and Climate :

Weather	Climate
1. Weather stands for actual atmospheric conditions for a short  period (a day or a week).	1. Climate is the aggre- gate of atmospheric conditions for a longer period (say 35 years).
2. The weather changes from day-to-day thus, cannot be generalised.	2. The climate is everlast-ing and static. It does not change so fre-quently.
3. Weather depends upon the dominant element	3. Climate is the compos-ite picture of all the el-ements spread over a longer period.
4. Weather is actually present at a place. It is what you get.	4. Climate is what you expect. It is arrived at by climatic means or averages.
5. Every type of weather can occur at one place.	5. A particular place can-not have all types ofclimates.
6. Weather refers to a particular place.	6. Climate refers to a par-ticular area.
7. Weather deals with individual elements of weather.	7. It deals with the com-bination of all the ele-ments of weather.
8. Weather is uncertain and we can only forecast for a short time ahead.	8. Climate has a high de-gree of accuracy and it is similar year after year.

Comparison Questions

Question 1. 
Distinguish between the Troposphere and Stratosphere.
Answer:

Troposphere	Stratosphere
1. It is the lowest layer of the atmosphere.	1. It is the second layer of the atmosphere above the earth.
2. Its height varies from 8 kms. at the poles to 20 kms. at the equator.	2. Its height varies from 16 kms. at the equator to 72 kms at the poles.
3. In this layer the tem-perature decreases at the rate of 1°C per 165 metres.	3. In this layer temperatures are very low and fairly constant.
4. It is a zone of convection currents.	4. It is the non-convective zone of the atmosphere.
5. Most of the water vapours, clouds and dust particles are found in this layer.	5. Clouds, dust particles and water vapours are practically absent in this layer.
6. Atmospheric	6. This zone is free from atmospheric disturbances.
7. Unstable rising air makes weather changes in this layer.	7. Jet stream is a powerful element in this layer.

Source Based Questions

1. Read the following paragraph and answer the questions given below:
Can human beings live without air? We eat food and drink water at intervals but we breathe every few seconds. Air is an important part of the survival of all organisms. Some organisms such as humans may survive for some time without water and food but cannot survive even a few minutes without air. We need to understand the atmosphere in greater detail. Atmosphere is a mixture of gasses those envelope the earth all round.

This contains life-giving gases such as oxygen for humans and animals; and carbon dioxide for plants. The air is an important part of the earth’s mass and 99% of the total mass of the atmosphere is confined to the height of 32 km from the surface of the earth. Air is colourless and odourless; and can be only felt when it blows as a wind.

(i) Which of the following is the most essential element for all living beings?
(a) Water 
(b) Air
(c) Food 
(d) Shelter
Answer: 
(b) Air

(ii) What are the basic need of humans?
(a) Food 
(b) Water
(c) Air 
(d) All of these
Answer: 
(d) All of these

(iii) Which of the following is a life-giving gas for plants?
(a) Oxygen 
(b) Nitrogen
(c) Carbon Dioxide 
(d) All of these 
Answer: 
(c) Carbon Dioxide

(iv) The total mass of the atmosphere is confined to height of km from the surface of the earth.
(a) 32 km 
(b) 33 km
(c) 34 km 
(d) 35 km
Answer: 
(a) 32 km

2. Read the following paragraph and answer the questions given below:
Meteorologically carbon dioxide is an important gas because it is transparent to the incoming solar radiation but opaque to the outgoing terrestrial radiation. Carbon dioxide absorbs a part of terrestrial radiation and reflects back some part of it towards the surface of the earth. This gas is largely responsible for greenhouse effect. Volume of other gases is constant but volume of this gas has been rising in the past few decades mainly due to the burning of fossil fuels. 

Carbon dioxide is also responsible for the increased temperature of the air. Another important components of the atmosphere is ozone found between 10 to 50 km above the surface of the earth and acts as a filter. It absorbs the ultra-violet rays radiating from the sun and prevents them from reaching the surface of the earth. 

(i) Name a meterologically important gas.
(a) Carbon dioxide 
(b) Oxygen 
(c) Nitrogen 
(d) All of these
Answer: 
(a) Carbon dioxide

(ii)Which of the following is largely responsible for greenhouse effect?
(a) Oxygen 
(b) Nitrogen
(c) Carbon dioxide 
(d) All of these 
Answer: 
(a) Oxygen

(iii) Where is ozone present?
(a) 10 to 50 km above the earth surface
(b) 50 to 51 km above the earth surface
(c) 20 to 30 km above the earth surface
(d) 30 to 50 km above the earth surface 
Answer: 
(a) 10 to 50 km above the earth surface 

HOTS QUESTIONS 

Question 1
Without water vapour and dust in the atmosphere, there would be no weather. Discuss.
Answer: 
Water vapour and dust particles combine together to produce contrasts in weather. Clouds and fogs are formed on dust particles. Water vapour is the source of energy for storms, cyclones, etc. These absorb the solar energy. If there were a dry atmosphere, there would have been no weather. 

SELF EVALUATION TEST

1. Define atmosphere.
2. What is the percentage of Nitrogen gas present in atmosphere?
3. Which rays are absorbed by ozone gas? 
4. What is ionosphere?
5. What are the causes of depletion of ozone layer? 
6. What is Thermosphere? 
7. Why is atmosphere held to the earth?
8. Explain the significance of atmosphere. 
9. Name the different layers of the atmosphere. 
10. Distinguish between weather and climate.