These Composition and Structure of Atmosphere Important Questions cover the most important MCQs, one-word questions, assertion and reason questions and descriptive questions from NCERT Class 11 Geography Chapter 7. The questions are prepared from NCERT concepts and important exam-oriented topics for quick revision and practice.
This page is useful for UPSC, SSC, PSC, Railway, CUET and Class 11 Geography preparation, helping students revise important concepts related to atmosphere, atmospheric composition, gases, ozone layer, water vapour, atmospheric layers and weather elements.
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Multiple Choice Questions (MCQs)
These MCQs from Composition and Structure of Atmosphere are designed for quick objective revision and competitive exam preparation. The questions cover important atmospheric concepts, atmospheric composition, atmospheric layers and weather-related processes discussed in the NCERT chapter.
The atmosphere is mainly composed of:
A. Only oxygen
B. Mixture of gases
C. Only nitrogen
D. Water vapour only
Answer: B. Mixture of gases | Page Reference: Page 64
Approximately 99 per cent of atmospheric mass is confined within:
A. 10 km
B. 20 km
C. 32 km
D. 100 km
Answer: C. 32 km | Page Reference: Page 64
Which gas is essential for respiration in humans and animals?
A. Carbon dioxide
B. Oxygen
C. Nitrogen
D. Helium
Answer: B. Oxygen | Page Reference: Page 64
Carbon dioxide is important because it:
A. Blocks all solar radiation
B. Causes earthquakes
C. Produces greenhouse effect
D. Creates ozone layer only
Answer: C. Produces greenhouse effect | Page Reference: Page 64
Which gas is transparent to incoming solar radiation but opaque to outgoing terrestrial radiation?
A. Oxygen
B. Nitrogen
C. Carbon dioxide
D. Helium
Answer: C. Carbon dioxide | Page Reference: Page 64
The increase in atmospheric carbon dioxide is mainly due to:
A. Earthquakes
B. Ocean tides
B. Burning of fossil fuels
D. Volcanic ash only
Answer: C. Burning of fossil fuels | Page Reference: Page 64
The ozone layer is mainly located between:
A. 0–5 km
B. 10–50 km
C. 60–80 km
D. 100–150 km
Answer: B. 10–50 km | Page Reference: Page 64
The ozone layer protects Earth from:
A. Infrared rays
B. Radio waves
C. Ultra-violet rays
D. Cosmic dust only
Answer: C. Ultra-violet rays | Page Reference: Page 64
Water vapour in the atmosphere mainly acts like a:
A. Mirror
B. Blanket
C. Barrier wall
D. Magnetic shield
Answer: B. Blanket | Page Reference: Page 64
Water vapour decreases from:
A. Poles to equator
B. Equator to poles
C. Oceans to mountains only
D. Plains to deserts only
Answer: B. Equator to poles | Page Reference: Page 64
Dust particles in the atmosphere act as:
A. Heat producers only
B. Hygroscopic nuclei
C. Ozone generators
D. Wind barriers
Answer: B. Hygroscopic nuclei | Page Reference: Page 65
Which atmospheric layer contains most weather phenomena?
A. Mesosphere
B. Stratosphere
C. Troposphere
D. Exosphere
Answer: C. Troposphere | Page Reference: Page 65
The average height of troposphere is about:
A. 5 km
B. 13 km
C. 32 km
D. 50 km
Answer: B. 13 km | Page Reference: Page 65
The thickness of troposphere is greatest near:
A. Poles
B. Tropics only
C. Equator
D. Temperate regions
Answer: C. Equator | Page Reference: Page 65
Temperature in troposphere decreases at the rate of:
A. 1°C per 100 m
B. 1°C per 165 m
C. 2°C per 100 m
D. 6°C per 1000 m only
Answer: B. 1°C per 165 m | Page Reference: Page 65
The boundary between troposphere and stratosphere is called:
A. Mesopause
B. Tropopause
C. Thermopause
D. Exobase
Answer: B. Tropopause | Page Reference: Page 65
Which atmospheric layer contains ozone layer?
A. Troposphere
B. Stratosphere
C. Mesosphere
D. Exosphere
Answer: B. Stratosphere | Page Reference: Page 65
The mesosphere extends up to about:
A. 50 km
B. 80 km
C. 120 km
D. 400 km
Answer: B. 80 km | Page Reference: Page 65
The ionosphere contains electrically charged particles called:
A. Molecules
B. Nuclei
C. Ions
D. Vapours
Answer: C. Ions | Page Reference: Page 65
Radio waves are reflected back to Earth by:
A. Troposphere
B. Mesosphere
C. Ionosphere
D. Exosphere
Answer: C. Ionosphere | Page Reference: Page 65
The uppermost atmospheric layer is:
A. Stratosphere
B. Mesosphere
C. Thermosphere
D. Exosphere
Answer: D. Exosphere | Page Reference: Page 66
Which layer is most important for biological activity?
A. Exosphere
B. Mesosphere
C. Troposphere
D. Thermosphere
Answer: C. Troposphere | Page Reference: Page 65
Dust particles are highly concentrated in:
A. Upper atmosphere only
B. Equatorial regions only
C. Lower atmosphere
D. Exosphere only
Answer: C. Lower atmosphere | Page Reference: Page 65
The temperature at mesopause reaches approximately:
A. 0°C
B. –20°C
C. –100°C
D. 100°C
Answer: C. –100°C | Page Reference: Page 65
The atmosphere gradually merges with outer space in:
A. Troposphere
B. Thermosphere
C. Exosphere
D. Mesosphere
Answer: C. Exosphere | Page Reference: Page 66
Which atmospheric component is highly variable?
A. Nitrogen
B. Oxygen
C. Water vapour
D. Argon
Answer: C. Water vapour | Page Reference: Page 64
Which atmospheric layer is directly responsible for weather and climate changes?
A. Stratosphere
B. Troposphere
C. Mesosphere
D. Exosphere
Answer: B. Troposphere | Page Reference: Page 65
Convectional currents are strongest near:
A. Poles
B. Equator
C. Mesosphere
D. Exosphere
Answer: B. Equator | Page Reference: Page 65
Which gas quantity becomes negligible at about 120 km height?
A. Nitrogen
B. Carbon dioxide
C. Oxygen
D. Ozone
Answer: C. Oxygen | Page Reference: Page 64
Which among the following is NOT an element of weather and climate?
A. Humidity
B. Winds
C. Pressure
D. Minerals
Answer: D. Minerals | Page Reference: Page 66
One-Word / Very Short Answer Questions
These one-word and factual questions help students quickly revise important atmospheric concepts, gases, atmospheric layers and weather elements from the chapter. The section is especially useful for UPSC, SSC, PSC, Railway, CUET and other objective examinations.
-
What surrounds Earth as a gaseous envelope?
Answer: Atmosphere | Page Reference: Page 64 -
Which gas is essential for respiration?
Answer: Oxygen | Page Reference: Page 64 -
Which gas causes greenhouse effect?
Answer: Carbon dioxide | Page Reference: Page 64 -
Which layer absorbs ultraviolet rays?
Answer: Ozone layer | Page Reference: Page 64 -
Between which heights is ozone mainly found?
Answer: 10–50 km | Page Reference: Page 64 -
Which atmospheric component acts like a blanket?
Answer: Water vapour | Page Reference: Page 64 -
What do dust particles act as for cloud formation?
Answer: Hygroscopic nuclei | Page Reference: Page 65 -
Which is the lowermost atmospheric layer?
Answer: Troposphere | Page Reference: Page 65 -
What is the average height of troposphere?
Answer: 13 km | Page Reference: Page 65 -
Which boundary separates troposphere and stratosphere?
Answer: Tropopause | Page Reference: Page 65 -
Which atmospheric layer contains ozone layer?
Answer: Stratosphere | Page Reference: Page 65 -
Which layer lies above stratosphere?
Answer: Mesosphere | Page Reference: Page 65 -
What is the upper boundary of mesosphere called?
Answer: Mesopause | Page Reference: Page 65 -
Which layer reflects radio waves?
Answer: Ionosphere | Page Reference: Page 65 -
Which particles are found in ionosphere?
Answer: Ions | Page Reference: Page 65 -
Which is the uppermost atmospheric layer?
Answer: Exosphere | Page Reference: Page 66 -
Which atmospheric layer is most important for weather changes?
Answer: Troposphere | Page Reference: Page 65 -
Which gas becomes negligible above 120 km?
Answer: Oxygen | Page Reference: Page 64 -
Which weather element measures moisture in air?
Answer: Humidity | Page Reference: Page 66 -
Which region has maximum troposphere thickness?
Answer: Equator | Page Reference: Page 65
Assertion and Reason Questions
These assertion and reason questions from Composition and Structure of Atmosphere help students develop conceptual clarity and analytical understanding of atmospheric composition, atmospheric layers and weather processes. They are highly useful for board exams and competitive examinations.
Assertion (A): Atmosphere is essential for survival of organisms.
Reason (R): Atmosphere contains life-supporting gases like oxygen and carbon dioxide.
Options:
A. Both A and R are true and R is the correct explanation
B. Both A and R are true but R is not the correct explanation
C. A is true but R is false
D. A is false but R is true
Correct Option: A | Page Reference: Page 64
Assertion (A): Carbon dioxide contributes to greenhouse effect.
Reason (R): Carbon dioxide absorbs terrestrial radiation and reflects part of it back to Earth.
Options:
A. Both A and R are true and R is the correct explanation
B. Both A and R are true but R is not the correct explanation
C. A is true but R is false
D. A is false but R is true
Correct Option: A | Page Reference: Page 64
Assertion (A): Ozone layer is important for life on Earth.
Reason (R): Ozone absorbs harmful ultraviolet radiation from the Sun.
Options:
A. Both A and R are true and R is the correct explanation
B. Both A and R are true but R is not the correct explanation
C. A is true but R is false
D. A is false but R is true
Correct Option: A | Page Reference: Page 64
Assertion (A): Water vapour acts like a blanket around Earth.
Reason (R): Water vapour preserves Earth’s radiated heat.
Options:
A. Both A and R are true and R is the correct explanation
B. Both A and R are true but R is not the correct explanation
C. A is true but R is false
D. A is false but R is true
Correct Option: A | Page Reference: Page 64
Assertion (A): Dust particles help in cloud formation.
Reason (R): Dust particles act as hygroscopic nuclei around which condensation occurs.
Options:
A. Both A and R are true and R is the correct explanation
B. Both A and R are true but R is not the correct explanation
C. A is true but R is false
D. A is false but R is true
Correct Option: A | Page Reference: Page 65
Assertion (A): Troposphere is the most important atmospheric layer for human life.
Reason (R): All weather and climate changes occur in troposphere.
Options:
A. Both A and R are true and R is the correct explanation
B. Both A and R are true but R is not the correct explanation
C. A is true but R is false
D. A is false but R is true
Correct Option: A | Page Reference: Page 65
Assertion (A): Troposphere is thicker near the equator.
Reason (R): Strong convectional currents transport heat to greater heights near equator.
Options:
A. Both A and R are true and R is the correct explanation
B. Both Aand R are true but R is not the correct explanation
C. A is true but R is false
D. A is false but R is true
Correct Option: A | Page Reference: Page 65
Assertion (A): Temperature decreases with height in troposphere.
Reason (R): Troposphere receives heat mainly from Earth’s surface.
Options:
A. Both A and R are true and R is the correct explanation
B. Both A and R are true but R is not the correct explanation
C. A is true but R is false
D. A is false but R is true
Correct Option: A | Page Reference: Page 65
Assertion (A): Stratosphere contains ozone layer.
Reason (R): Ozone layer protects life by absorbing ultraviolet rays.
Options:
A. Both A and R are true and R is the correct explanation
B. Both A and R are true but R is not the correct explanation
C. A is true but R is false
D. A is false but R is true
Correct Option: A | Page Reference: Page 65
Assertion (A): Ionosphere is important for radio communication.
Reason (R): Radio waves are reflected back to Earth by ionosphere.
Options:
A. Both A and R are true and R is the correct explanation
B. Both A and R are true but R is not the correct explanation
C. A is true but R is false
D. A is false but R is true
Correct Option: A | Page Reference: Page 65
Assertion (A): Mesosphere is extremely cold.
Reason (R): Temperature decreases with increasing altitude in mesosphere.
Options:
A. Both A and R are true and R is the correct explanation
B. Both A and R are true but R is not the correct explanation
C. A is true but R is false
D. A is false but R is true
Correct Option: A | Page Reference: Page 65
Assertion (A): Water vapour amount varies from place to place.
Reason (R): Temperature and moisture conditions vary across regions.
Options:
A. Both A and R are true and R is the correct explanation
B. Both A and R are true but R is not the correct explanation
C. A is true but R is false
D. A is false but R is true
Correct Option: A | Page Reference: Page 64
Assertion (A): Oxygen becomes negligible at greater heights.
Reason (R): Atmospheric composition changes with altitude.
Options:
A. Both A and R are true and R is the correct explanation
B. Both A and R are true but R is not the correct explanation
C. A is true but R is false
D. A is false but R is true
Correct Option: A | Page Reference: Page 64
Assertion (A): Dust particles are more concentrated in subtropical and temperate regions.
Reason (R): Dry winds are more common in these regions.
Options:
A. Both A and R are true and R is the correct explanation
B. Both A and R are true but R is not the correct explanation
C. A is true but R is false
D. A is false but R is true
Correct Option: A | Page Reference: Page 65
Assertion (A): Exosphere gradually merges with outer space.
Reason (R): Atmospheric contents become extremely rarefied at higher altitudes.
Options:
A. Both A and R are true and R is the correct explanation
B. Both A and R are true but R is not the correct explanation
C. A is true but R is false
D. A is false but R is true
Correct Option: A | Page Reference: Page 66
Important Exam-Based Concept Questions
These important descriptive and analytical questions from Composition and Structure of Atmosphere are useful for board examinations and competitive exams. The questions focus on conceptual understanding, atmospheric composition and atmospheric layers.
1. Explain the meaning and importance of atmosphere.
Page Reference: Page 64
2. Describe the composition of atmosphere.
Page Reference: Page 64–65
3. Explain the importance of carbon dioxide in atmosphere.
Page Reference: Page 64
4. Discuss the causes and effects of greenhouse effect.
Page Reference: Page 64
5. Explain the role of ozone layer in protecting life on Earth.
Page Reference: Page 64–65
6. Describe the distribution and importance of water vapour in atmosphere.
Page Reference: Page 64
7. Explain the significance of dust particles in atmosphere.
Page Reference: Page 65
8. Describe the structure of atmosphere with suitable diagram explanation.
Page Reference: Page 65–66
9. Explain the characteristics of troposphere.
Page Reference: Page 65
10. Why is troposphere considered the most important atmospheric layer?
Page Reference: Page 65
11. Explain the concept of tropopause.
Page Reference: Page 65
12. Discuss the characteristics and importance of stratosphere.
Page Reference: Page 65
13. Explain the significance of ozone layer in stratosphere.
Page Reference: Page 65
14. Describe the characteristics of mesosphere.
Page Reference: Page 65
15. Explain the role of ionosphere in radio communication.
Page Reference: Page 65
16. Discuss the characteristics of exosphere.
Page Reference: Page 66
17. Differentiate between troposphere and stratosphere.
Page Reference: Page 65
18. Explain why atmospheric density decreases with altitude.
Page Reference: Page 65
19. Discuss the major elements of weather and climate.
Page Reference: Page 66
20. Explain how atmospheric composition supports life on Earth.
Page Reference: Page 64–66
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