NCERT Solutions for Class 7 Social Science (Geography) – Our Environment Chapter4- Air

We are surrounded by air. It’s a concentration of several gases. The air in the earth’s atmosphere is roughly 78% nitrogen and 21% oxygen. Our atmosphere is separated into five levels- troposphere, stratosphere, mesosphere, thermosphere, and exosphere. The climate of a place is represented by the average weather condition of a location over a longer period. NCERT solutions for Class 7 Geography Chapter 4 gives a basic understanding of the chapter and will play a crucial part in preparing for the final exam.

NCERT Solutions for Class 7 Social Science Chapter 4 – Air 

The theme of Chapter 4 of the NCERT solution for Class 7 Geography is air and atmosphere that surrounds the globe. It begins with an explanation of its makeup in the earth’s atmosphere and the percentages of various gases in the atmosphere, the structure of the earth’s atmosphere. Temperature, air pressure, moisture, and winds are also discussed in Chapter 4 of Class 7 Geography. The NCERT solutions are available on the official website of  Extramarks.

Access NCERT Solutions for Class 7 Social Science (Geography) Chapter – 4 Air

The NCERT solutions are prepared by subject experts and teachers with years of experience in their respective subjects. They are aware of the topics where students can fall behind and face difficulties in understanding difficult concepts. Keeping these facts in mind, they use simple and easy to understand language while preparing the solutions so that students could quickly grasp the concepts and prepare for their exams thoroughly.

Chapter 4: Air

Natural disasters, global warming, and its many repercussions on human life are discussed in this chapter. This chapter has a separate section discussing greenhouse gases, air density, heat, and the sun. With the rise of various environmental challenges in today’s society, students need to have a strong foundation and understanding of all the issues and activities occurring in our environment. 

What is The Composition of The Earth’s Atmosphere?

The earth’s atmosphere is around 480 kilometres thick. However,. It lies 16 kilometres of the surface. Air pressure is approximately 1 kilogram per square centimetre at sea, but air pressure decreases as height increases. At 10,000 feet, the air pressure is 0.7 kilograms per square centimetre.

According to NASA, the following gases make up the earth’s atmosphere:

  • 78% nitrogen
  • Oxygen content: 21%
  • 0.93% argon
  • 0.04% carbon dioxide
  • Trace amounts of Neon, helium, methane, hydrogen, and water vapour are present .

Atmospheric Layers

The earth’s atmosphere is divided into five levels.

  • Troposphere: The troposphere is the most important layer of the atmosphere. The average height of the troposphere is 13km. The air we breathe is found in the troposphere, and all the weather phenomena such as fog, rainfall and hailstorm occur in this layer.
  • Stratosphere: The stratosphere is the second layer, which extends to a height of around 50 kilometres above the ground. This layer is rich in ozone and absorbs the sun’s damaging rays. This layer is free from clouds and associated weather phenomenon. It is for this reason that jet planes travel through this layer. 
  • Mesosphere: This is the third layer of the atmosphere. It begins at 50 kilometres above sea level and extends to 80 kilometres. According to scientists, meteorites have been identified to burn up in this layer. 
  • Thermosphere:  This layer extends between 80-400km. There is a sudden increase in temperature with increasing height. Because of the low air density in this region, space shuttles fly here, and International Space Stations orbits the earth. The occurrence of auroras is well-known in this stratum.  This layer helps in radio transmission. Radio waves that are transmitted from the earth are reflected by this layer.
  • Exosphere: The exosphere is the outermost  layer of the earth’s atmosphere.It has very thin air. It is made up of light gases like hydrogen and helium.

Climate and Weather

Because of its diverse environment, the earth supports a broad range of living organisms. The earth’s climate varies from extreme cold at the poles to tropical heat on the equator. Weather is the daily atmospheric condition of a particular place with respect to temperature, air pressure and wind is called weather. On the other hand the average weather of an area over 30 years or more is referred to as regional climate. The climate of a region can be sunny, windy, dry, or humid. The global system of the earth is an average of all regional systems. 

Why Choose Extramarks as Your Study Companion?

It is critical to recognize the chapters that require extra effort to achieve good grades in a subject. The NCERT Solutions Class 7 Geography Chapter 4 has been created to help students understand each concept  very well. Having a strong foundation and a firm grasp on each topic allows students to score good marks in the exams. This is the reason Extramarks is considered as one of the best e-learning platforms that offers quality study materials to the students of all classes. 

NCERT Class 7 Social Science Our Environment Chapterwise Solutions

NCERT Class 7 Social Science Chapterwise Solutions help students achieve their desired targets effectively.

  • Chapter 1 – Environment
  • Chapter 2 – Inside Our Earth
  • Chapter 3 – Our Changing Earth
  • Chapter 4 – Air
  • Chapter 5 – Water
  • Chapter 6 – Natural Vegetation and Wildlife
  • Chapter 7 – Human Environment-Settlement, Transport and Communication
  • Chapter 8 – Human Environment Interactions – The Tropical and the Subtropical Region
  • Chapter 9 –  Life in the  Temperate Grasslands
  • Chapter 10- Life in the Deserts

NCERT Solutions for Class 7 Social Science

Extramarks provide the most accurate answers to all of the questions from the Social Science textbook. The study materials contain clear explanations and in-depth discussions. Adequate approaches and tactics are offered in the NCERT Solutions so that students have no difficulty answering textbook questions. Academic professionals with years of experience drafts the solutions based on the most recent CBSE syllabus. Students are always advised to follow the NCERT solutions and enjoy the maximum benefits from them.

Q.1 Answer the following questions.

(i) What is atmosphere?

(ii) Which two gases make the bulk of the atmosphere?

(iii) Which gas creates green house effect in the atmosphere?

(iv) What is weather?

(v) Name three types of rainfall?

(vi) What is air pressure?

Ans-

(i) The huge blanket of air that surrounds the earth is known as atmosphere.

(ii) The gases which make the bulk of atmosphere are nitrogen and oxygen.

(iii) Carbon dioxide creates green house effect in the atmosphere.

(iv) The state of atmosphere at a particular place and time is known as weather. It is the hour-to-hour, day to day condition of the atmosphere.

(v) Three types of rainfall are:

(a) The Convectional Rainfall
(b) The Relief or Orographic Rainfall, and
(c) The Cyclonic Rainfall

(vi) The pressure exerted by the weight of air on the earth’s surface is known as air pressure.

Q.2 (i) Which of the following gases protect us from harmful sun rays?

(a) Carbon dioxide (b) Nitrogen (c) Ozone

(ii) The most important layer of the atmosphere is:

(a) Troposphere (b) Thermosphere (c) Mesosphere

(iii) Which of the following layers of the atmosphere is free from clouds?

(a) Troposphere (b) Stratosphere (c) Mesosphere

(iv) As we go up the layers of the atmosphere, the pressure:

(a) Increases (b) Decreases (c) Remains the same

(v) When precipitation comes down to the earth in the liquid form, it is called:

(a) Cloud (b) Rain (c) Snow

Ans-

(i) (c) Ozone ✓

(ii) (a) Troposphere ✓

(iii) (b) Stratosphere ✓

(iv) (b) Decreases ✓

(v) (b) Rain ✓

Q.3 Match the following.

(i) Trade winds (a) Incoming solar energy
(ii) Loo (b) Seasonal wind
(iii) Monsoon (c) Horizontal movement of air
(iv) Wind (d) Layer of ozone gas
(e) Permanent wind
(f) Local wind

Ans-

(i) Trade winds (e) Permanent wind
(ii) Loo (f) Local wind
(iii) Monsoon (b) Seasonal wind
(iv) Wind (c) Horizontal movement of air

Q.4 Give reasons.

(i) Wet clothes take longer time to dry on a humid day.

(ii) Amount of insolation decreases from equator towards poles.

Ans-

(i) Water from wet clothes evaporates due to the presence of sun and wind. The rate of evaporation is much slower on a humid day than that on a dry day.This is because the air already has some amount of moisture present in it. Hence, it takes longer to dry wet clothes.

(ii) Sunlight falls almost vertically on the equator, while it falls at a slanting angle on the poles. Therefore,the amount of insolation decreases from equator towards the poles. The amount of insolation received by the equatorial regions is greater than that received by the polar regions.

 

Q.5 (i) Solve this crossword puzzle with the help of given clues.

Across:

6. An Indian tree having extraordinary quality of providing oxygen round the clock

8. Gas present in atmosphere occupying only 0.03% by volume

11. Outermost layer of atmosphere

12. Mixture of many gases

14. Life giving gas

15. Air in motion: Wind

16. An Indian tree valued highly for medicinal properties

18. Gas protecting us from harmful sunrays

19. Low pressure area

Down:

1. Amount of water vapour in air

2. Condensation of water vapour around dust particles in atmosphere

3. Example of local wind blowing in summer in northern India

4. Short term changes in atmosphere

5. Precipitation in liquid form

7. Blanket of air around the earth

9. Instrument to measure pressure

10. Incoming solar radiation

13. Reduces visibility in winters

17. It is——-time when sun is overhead.

(ii) Make a weather calendar for one week. Use pictures or symbols to show different types of weather. You can use more than one symbol in a day, if the weather changes.

Ans-

(i)

Across:

6. An Indian tree having extraordinary quality of providing oxygen round the clock: Peepal

8. Gas present in atmosphere occupying only 0.03% by volume: Carbon dioxide

11. Outermost layer of atmosphere: Exosphere

12. Mixture of many gases: Air

14. Life giving gas: Oxygen

15. Air in motion: Wind

16. An Indian tree valued highly for medicinal properties: Neem

18. Gas protecting us from harmful sunrays: Ozone

19. Low pressure area: Cyclone

Down:

1. Amount of water vapour in air: Humidity

2. Condensation of water vapour around dust particles in atmosphere: Cloud

3. Example of local wind blowing in summer in northern India: Loo

4. Short term changes in atmosphere: Weather
5. Precipitation in liquid form: Rain

7. Blanket of air around the earth: Atmosphere

9. Instrument to measure pressure: Barometre

10. Incoming solar radiation: Insolation

13. Reduces visibility in winters: Fog

17. It is noon time when sun is overhead.

(ii)

 

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FAQs (Frequently Asked Questions)

Wind is a type of air element that refers to the movement of atmospheric air from one location to another. When gases from a high-pressure location flow to a low-pressure area, this happens. Winds are classified according to their speed, the region in which they occur, and their impact. Winds can erode and deposit landforms over a long period. They also impact the world’s enormous wildfires by providing oxygen to the fuel. 

 

Atmosphere is a coat of air that surrounds the globe. Gases with concentrations such as nitrogen and oxygen make up the atmosphere. Carbon dioxide, helium, and other gases make up the rest of the proportion.

NCERT solutions for Class 7 Geography Chapter 4 – “Air” comprises -Composition of the atmosphere, Structure of atmosphere with description of five layers of the atmosphere, weather and climate which briefly covers temperature,Air pressure and wind. The Extramarks study guide provides students with revision notes, expert-verified solutions, mock tests, and doubt-clearing sessions to help them  in their exam preparation.

In Chapter 4 of Class 7,  Air is defined as a mixture of various gases found in the earth’s atmosphere. Nitrogen makes up 78% of the gas, oxygen makes up 21%, and the rest is made up of inert gases. The purest air is supposed to be colourless and odourless. Humans cannot thrive on the planet without air.