Composition and Structure of Atmosphere Important Questions
These Composition and Structure of Atmosphere Important Questions cover important NCERT concepts related to atmosphere, atmospheric composition, gases, ozone layer, water vapour, atmospheric layers and weather elements.
The chapter-wise questions include MCQs, one-word questions, assertion and reason questions and analytical descriptive questions useful for UPSC, SSC, Railways, State PSC, CUET, CBSE board exams and competitive examinations.
NCERT Page Coverage: Page 64–66
Table of Contents
Multiple Choice Questions (MCQs)
These MCQs from Composition and Structure of Atmosphere help students revise important concepts related to atmospheric composition, atmospheric layers and weather-related processes.
MCQ 1
The atmosphere is mainly composed of:
- A. Only oxygen
- B. Mixture of gases
- C. Only nitrogen
- D. Water vapour only
Page Reference: Page 64
MCQ 2
Approximately 99 per cent of atmospheric mass is confined within:
- A. 10 km
- B. 20 km
- C. 32 km
- D. 100 km
Page Reference: Page 64
MCQ 3
Which gas is essential for respiration in humans and animals?
- A. Carbon dioxide
- B. Oxygen
- C. Nitrogen
- D. Helium
Page Reference: Page 64
MCQ 4
Carbon dioxide is important because it:
- A. Blocks all solar radiation
- B. Causes earthquakes
- C. Produces greenhouse effect
- D. Creates ozone layer only
Page Reference: Page 64
MCQ 5
Which gas is transparent to incoming solar radiation but opaque to outgoing terrestrial radiation?
- A. Oxygen
- B. Nitrogen
- C. Carbon dioxide
- D. Helium
Page Reference: Page 64
MCQ 6
The increase in atmospheric carbon dioxide is mainly due to:
- A. Earthquakes
- B. Ocean tides
- C. Burning of fossil fuels
- D. Volcanic ash only
Page Reference: Page 64
MCQ 7
The ozone layer is mainly located between:
- A. 0–5 km
- B. 10–50 km
- C. 60–80 km
- D. 100–150 km
Page Reference: Page 64
MCQ 8
The ozone layer protects Earth from:
- A. Infrared rays
- B. Radio waves
- C. Ultra-violet rays
- D. Cosmic dust only
Page Reference: Page 64
MCQ 9
Water vapour in the atmosphere mainly acts like a:
- A. Mirror
- B. Blanket
- C. Barrier wall
- D. Magnetic shield
Page Reference: Page 64
MCQ 10
Water vapour decreases from:
- A. Poles to equator
- B. Equator to poles
- C. Oceans to mountains only
- D. Plains to deserts only
Page Reference: Page 64
MCQ 11
Dust particles in the atmosphere act as:
- A. Heat producers only
- B. Hygroscopic nuclei
- C. Ozone generators
- D. Wind barriers
Page Reference: Page 65
MCQ 12
Which atmospheric layer contains most weather phenomena?
- A. Mesosphere
- B. Stratosphere
- C. Troposphere
- D. Exosphere
Page Reference: Page 65
MCQ 13
The average height of troposphere is about:
- A. 5 km
- B. 13 km
- C. 32 km
- D. 50 km
Page Reference: Page 65
MCQ 14
The thickness of troposphere is greatest near:
- A. Poles
- B. Tropics only
- C. Equator
- D. Temperate regions
Page Reference: Page 65
MCQ 15
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
Page Reference: Page 65
MCQ 16
The boundary between troposphere and stratosphere is called:
- A. Mesopause
- B. Tropopause
- C. Thermopause
- D. Exobase
Page Reference: Page 65
MCQ 17
Which atmospheric layer contains ozone layer?
- A. Troposphere
- B. Stratosphere
- C. Mesosphere
- D. Exosphere
Page Reference: Page 65
MCQ 18
The mesosphere extends up to about:
- A. 50 km
- B. 80 km
- C. 120 km
- D. 400 km
Page Reference: Page 65
MCQ 19
The ionosphere contains electrically charged particles called:
- A. Molecules
- B. Nuclei
- C. Ions
- D. Vapours
Page Reference: Page 65
MCQ 20
Radio waves are reflected back to Earth by:
- A. Troposphere
- B. Mesosphere
- C. Ionosphere
- D. Exosphere
Page Reference: Page 65
MCQ 21
The uppermost atmospheric layer is:
- A. Stratosphere
- B. Mesosphere
- C. Thermosphere
- D. Exosphere
Page Reference: Page 66
MCQ 22
Which layer is most important for biological activity?
- A. Exosphere
- B. Mesosphere
- C. Troposphere
- D. Thermosphere
Page Reference: Page 65
MCQ 23
Dust particles are highly concentrated in:
- A. Upper atmosphere only
- B. Equatorial regions only
- C. Lower atmosphere
- D. Exosphere only
Page Reference: Page 65
MCQ 24
The temperature at mesopause reaches approximately:
- A. 0°C
- B. –20°C
- C. –100°C
- D. 100°C
Page Reference: Page 65
MCQ 25
The atmosphere gradually merges with outer space in:
- A. Troposphere
- B. Thermosphere
- C. Exosphere
- D. Mesosphere
Page Reference: Page 66
MCQ 26
Which atmospheric component is highly variable?
- A. Nitrogen
- B. Oxygen
- C. Water vapour
- D. Argon
Page Reference: Page 64
MCQ 27
Which atmospheric layer is directly responsible for weather and climate changes?
- A. Stratosphere
- B. Troposphere
- C. Mesosphere
- D. Exosphere
Page Reference: Page 65
MCQ 28
Convectional currents are strongest near:
- A. Poles
- B. Equator
- C. Mesosphere
- D. Exosphere
Page Reference: Page 65
MCQ 29
Which gas quantity becomes negligible at about 120 km height?
- A. Nitrogen
- B. Carbon dioxide
- C. Oxygen
- D. Ozone
Page Reference: Page 64
MCQ 30
Which among the following is NOT an element of weather and climate?
- A. Humidity
- B. Winds
- C. Pressure
- D. Minerals
Page Reference: Page 66
One-Word / Very Short Answer Questions
| Question | Answer | Page Reference |
|---|---|---|
| What surrounds Earth as a gaseous envelope? | Atmosphere | Page 64 |
| Which gas is essential for respiration? | Oxygen | Page 64 |
| Which gas causes greenhouse effect? | Carbon dioxide | Page 64 |
| Which layer absorbs ultraviolet rays? | Ozone layer | Page 64 |
| Between which heights is ozone mainly found? | 10–50 km | Page 64 |
| Which atmospheric component acts like a blanket? | Water vapour | Page 64 |
| What do dust particles act as for cloud formation? | Hygroscopic nuclei | Page 65 |
| Which is the lowermost atmospheric layer? | Troposphere | Page 65 |
| What is the average height of troposphere? | 13 km | Page 65 |
| Which boundary separates troposphere and stratosphere? | Tropopause | Page 65 |
| Which atmospheric layer contains ozone layer? | Stratosphere | Page 65 |
| Which layer lies above stratosphere? | Mesosphere | Page 65 |
| What is the upper boundary of mesosphere called? | Mesopause | Page 65 |
| Which layer reflects radio waves? | Ionosphere | Page 65 |
| Which particles are found in ionosphere? | Ions | Page 65 |
| Which is the uppermost atmospheric layer? | Exosphere | Page 66 |
| Which atmospheric layer is most important for weather changes? | Troposphere | Page 65 |
| Which gas becomes negligible above 120 km? | Oxygen | Page 64 |
| Which weather element measures moisture in air? | Humidity | Page 66 |
| Which region has maximum troposphere thickness? | Equator | Page 65 |
Assertion and Reason Questions
Question 1
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
Page Reference: Page 64
Question 2
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
Page Reference: Page 64
Question 3
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
Page Reference: Page 64
Question 4
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
Page Reference: Page 64
Question 5
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
Page Reference: Page 65
Question 6
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
Page Reference: Page 65
Question 7
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 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
Page Reference: Page 65
Question 8
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
Page Reference: Page 65
Question 9
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
Page Reference: Page 65
Question 10
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
Page Reference: Page 65
Question 11
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
Page Reference: Page 65
Question 12
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
Page Reference: Page 64
Question 13
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
Page Reference: Page 64
Question 14
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
Page Reference: Page 65
Question 15
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
Page Reference: Page 66
Important Exam-Based Concept Questions
Question 1
Explain the meaning and importance of atmosphere.
Page Reference: Page 64
Question 2
Describe the composition of atmosphere.
Page Reference: Page 64–65
Question 3
Explain the importance of carbon dioxide in atmosphere.
Page Reference: Page 64
Question 4
Discuss the causes and effects of greenhouse effect.
Page Reference: Page 64
Question 5
Explain the role of ozone layer in protecting life on Earth.
Page Reference: Page 64–65
Question 6
Describe the distribution and importance of water vapour in atmosphere.
Page Reference: Page 64
Question 7
Explain the significance of dust particles in atmosphere.
Page Reference: Page 65
Question 8
Describe the structure of atmosphere with suitable diagram explanation.
Page Reference: Page 65–66
Question 9
Explain the characteristics of troposphere.
Page Reference: Page 65
Question 10
Why is troposphere considered the most important atmospheric layer?
Page Reference: Page 65
Question 11
Explain the concept of tropopause.
Page Reference: Page 65
Question 12
Discuss the characteristics and importance of stratosphere.
Page Reference: Page 65
Question 13
Explain the significance of ozone layer in stratosphere.
Page Reference: Page 65
Question 14
Describe the characteristics of mesosphere.
Page Reference: Page 65
Question 15
Explain the role of ionosphere in radio communication.
Page Reference: Page 65
Question 16
Discuss the characteristics of exosphere.
Page Reference: Page 66
Question 17
Differentiate between troposphere and stratosphere.
Page Reference: Page 65
Question 18
Explain why atmospheric density decreases with altitude.
Page Reference: Page 65
Question 19
Discuss the major elements of weather and climate.
Page Reference: Page 66
Question 20
Explain how atmospheric composition supports life on Earth.
Page Reference: Page 64–66
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