NCERT Solutions for Class 7 Social Chapter 4 - Air

1. Answer the following questions.

i. What is atmosphere?

Ans: The vast blanket of air around the earth’s surface is called the atmosphere.

ii. Which two gases make the bulk of atmosphere?

Ans: Nitrogen and Oxygen make up the bulk of the atmosphere.

iii. Which gas creates greenhouse effect in the atmosphere?

Ans: Carbon dioxide creates greenhouse effect in the atmosphere

iv. What is weather?

Ans: Observation of the physical features such as temperature, wind conditions, etc. over a short area for a short amount of time is called weather.

v. Name three types of rainfall.

Ans: The three types of rainfall are topographic, convectional and frontal.

vi. What is air pressure?

Ans: The pressure exerted by the atmosphere due to its weight over a region is called atmospheric pressure.

2. Tick the correct answer:

i. Which of the following gases protects us from harmful sun rays?

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

Ans: (c) Ozone

ii. The most important layer of the atmosphere is.

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

Ans: (a) Troposphere.

iii. Which of the following layers of atmosphere free from clouds?

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

Ans: (b) Stratosphere.

iv. As we go up the layers of the atmosphere, the pressure

(a) Increases. (b) Decreases. (c) Remain same

Ans: (b) Decreases.

v. When precipitation comes down to the earth liquid form, it is called:

(a)  Cloud (b) Rain (c) Snow

Ans: (b) Rain

1. Match the following:

Ans:

4. Give reasons.

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

Ans:  It is because on a humid day, the air is already saturated with water vapour so it cannot absorb the water from the clothes.

ii. Amount of insolation decreases from equator towards poles?

Ans: It is because the angle of sunrays falling on the earth decreases from equator to the poles. So, insolation decreases towards the poles.

5. For Fun

i. Solve this crossword puzzle with the help of given clues (on page no.28):

Ans:

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. For example, the sun comes out when rain stops. An example is given below: 

Day	Weather
	Rainy Day
	Thunderstorms
	Sunny Day
	Cloudy Day

Chapter 4: Air

The chapter also included topics such as natural disasters, global warming, and the various effects that it has on human life. Separate fun facts such as greenhouse gases, air density, heat, and sun have a separate section in the chapter. With a massive increase in several environmental issues in today's world, the students need to have some basic knowledge about the topics that will help the coming generation survive in the future. Keeping this in mind, the Class 7 Geography Chapter 4 explains the topic of environmental science compactly and straightforwardly.

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What is The Composition of The Earth's Atmosphere?

Earth's atmosphere is about 480 kilometres thick, but most of it is 16 Km within the surface. As air pressure decreases with altitude, even air pressure is around 1 kilogram per square centimetre at sea. At 10,000 feet, the air pressure is 0.7 kg per square centimetres.

According to NASA, Earth's atmospheric layer is composed of the following gases:

• Nitrogen: 78%

• Oxygen: 21%

• Argon: 0.93%

• Carbon Dioxide: 0.04%

• Trace amounts of neon, helium, methane, hydrogen as well as water vapour.

Atmospheric Layers

Earth's atmosphere is divided into five main layers. 

1. Troposphere

2. Stratosphere

3. Mesosphere

4. Thermosphere

5. Exosphere

The Troposphere is the first layer of the Earth’s atmosphere and is closest to the surface. It is about 7 to 20 km thick and contains most of the Earth's atmosphere. Air is warmer near the growing and gets colder as you rise. Nearly all of the Earth's water vapour and dust are found in this layer. The stratosphere is the second layer, and it extends to about 50 km above the ground. This layer has ozone in abundance and absorbs the harmful rays of the sun. The air in this layer is very dry. It is because of this reason that jet aircraft fly in this layer. The mesosphere starts at 50 km above the ground and continues till 85 km. The mesosphere's top is called the mesopause, and it is the coldest part of the Earth's atmosphere. The temperature here goes to below -130 degrees Fahrenheit. Scientists have recently found out that meteorites burn up in this layer.

The thermosphere extends to about 90 Km. This region's air density is low, and hence this is the region where space shuttles flew and International Space Stations orbit the Earth. This layer is famous for the occurrence of auroras. The exosphere is the highest layer in the Earth's atmosphere and is the thinnest. It is mainly composed of hydrogen and helium particles.

Climate and Weather

Earth supports a wide variety of living beings because of its diverse climate. From extreme cold at the poles to the tropical heat at the Equator, the climate of Earth is varying. The regional climate is described as the weather of a place over 30 years or more. A region's climate can be sunny, windy, dry, or humid. Earth's global climate is an average of all the regional climates. Today, rapid warming as a result of an increase in human activities that are trapping heat in the atmosphere.

Why Choose Vedantu as Your Study Companion?

In order to get maximum marks in a subject, it is important to understand the chapters that need extra effort. The Vedantu NCERT Class 7 Geography Chapter 4 has been designed to allow the students to understand every question specifically that appears in each section. While preparing for your exams, nothing is more critical than resourceful NCERT solutions. Getting a hold on the Class 7 Geography Chapter 4 solutions lets you get a good grasp on each topic. Get a hold on your Class 7 NCERT Solution for Geography Chapter 4.

Solved Example

1. What are the six types of climates? 

Ans: The six types of climates are:

1. Polar Chill

2. Temperate Region

3. Arid Zone

4. Damp Tropical Regions 

5. The Mild Mediterranean

6. The Cold Tundra

2. Mention the six elements of weather and climate.

Ans: The six primary components of weather are:

1. Temperature

2. Atmospheric Pressure

3. Wind

4. Humidity

5. Precipitation 

6. Cloudiness 

Importances of NCERT Solutions for Class 7 Social Chapter 4 - Air

NCERT Solutions for Class 7 Social Science Chapter 4, "Air," hold significant importance for students. Firstly, they align precisely with the NCERT curriculum, ensuring that students receive a comprehensive and accurate understanding of the subject matter. Secondly, these solutions provide clarity on complex concepts related to the composition, importance, and challenges associated with our Earth's atmosphere. They serve as a vital tool for exam preparation, offering step-by-step explanations and solutions to exercises, enabling students to practise and gauge their knowledge. 

Furthermore, by delving into these solutions, students gain a deeper awareness of the environmental issues linked to air quality and pollution, contributing to their role as responsible global citizens. In essence, these NCERT Solutions for Class 7 Social Chapter 4 play a pivotal role in fostering a holistic understanding of our environment and its critical components like the air we breathe.

Conclusion 

In conclusion, Vedantu's NCERT Solutions for Class 7 Social Science Chapter 4 - "Air" are an invaluable educational resource for students. These solutions provide a structured and comprehensive approach to understanding the complex topic of our planet's atmosphere. They align seamlessly with the NCERT curriculum, ensuring that students receive accurate and well-explained answers to their questions.

Moreover, these solutions aid in exam preparation by offering clarity on crucial concepts related to air composition, environmental issues, and the importance of clean air. By utilising Vedantu's NCERT Solutions, students can enhance their knowledge, critical thinking skills, and overall academic performance, ultimately fostering a greater appreciation for the significance of air in our lives and the environment.