NCERT Solutions for Class 6 Science Chapter 11

The chapter Air Around Us delves into the invisible world of air, explaining its properties, importance, and various components. Here’s a concise summary of Air Around Us:

1. What is air?

We cannot see air, but we can feel its presence through wind and its effects on objects.

2. Composition of air:

Air is mainly composed of nitrogen (78%) and oxygen (21%).

It also contains smaller amounts of carbon dioxide, water vapor, and other trace gases.

3. Properties of air:

Occupies space: Air fills all the empty spaces around us and exerts pressure on objects.

Has weight: Although we cannot feel it easily, air has weight due to the gravity pulling on its molecules.

Can be compressed: Air can be squeezed into a smaller space, like inflating a balloon.

Expands when heated: As air heats up, its molecules move faster and spread further apart, causing it to expand.

4. Importance of air:

Essential for life: Living organisms like humans, animals, and plants need oxygen from the air for respiration.

Combustion: Air is necessary for burning, providing the oxygen needed for combustion to occur.

Weather: Air plays a crucial role in weather phenomena like wind, rain, and clouds.

Transportation: Airplanes and balloons use the lift provided by air for flight.

5. Pollution:

The chapter might briefly introduce the concept of air pollution, highlighting the harmful effects of pollutants on the environment and human health.

Additional points:

The chapter might use diagrams and illustrations to explain the composition of air and its properties.

Simple experiments or demonstrations might be used to reinforce the concepts learned.

NCERT Solutions for Class 6 Science Chapter 11 Air Around Us

Exercises

1. What is the composition of air?

Ans : Air is a mixture of several gases, but the two main components are:

Nitrogen (approximately 78%): This colorless and odorless gas plays a crucial role in several ways:
- Maintains atmospheric pressure: Nitrogen acts as a “filler” gas, diluting the oxygen concentration and preventing combustion from being too rapid.
- Provides stability: It helps regulate the Earth’s temperature by preventing excessive heat gain or loss.
- Supports life indirectly: While not directly used by most organisms, it plays an ecological role in nitrogen fixation by some bacteria, which is essential for plant growth.
Oxygen (approximately 21%): This colorless and odorless gas is vital for life:
- Cellular respiration: All living organisms, except some anaerobic bacteria, depend on oxygen for cellular respiration, the process by which they convert nutrients into energy.

In addition to these major components, air also contains:

Carbon dioxide (around 0.04%): This gas is essential for:
- Photosynthesis: Plants use carbon dioxide and sunlight to produce food (glucose) through photosynthesis.
- Regulating Earth’s temperature: Carbon dioxide plays a role in the greenhouse effect, trapping heat from the sun and influencing global temperature. However, excessive levels of carbon dioxide contribute to climate change.

2. Which gas in the atmosphere is essential for respiration?

Ans : The gas in the atmosphere essential for respiration is oxygen (O₂).

Here’s why:

Cellular respiration: Most living organisms, including humans, animals, and plants (except some anaerobic bacteria), rely on a process called cellular respiration to convert nutrients into energy.
Oxygen’s role: During cellular respiration, oxygen is used by the cells to break down food molecules and release energy. This process is crucial for various functions like growth, development, and maintaining bodily processes.
Lack of oxygen: Without sufficient oxygen, cellular respiration cannot occur effectively, leading to cell death and ultimately, organism death.

3. How will you prove that air supports burning?

Ans : There are two common ways to demonstrate that air supports burning:

Method 1: Using a candle and a jar

Materials:

A candle
A glass jar or beaker
Matches or lighter

Procedure:

Light the candle and let it burn for a few seconds.
Carefully place the glass jar over the burning candle.
Observe what happens to the flame.

Observation: After a short while, the flame will extinguish.

Explanation:

The burning candle uses the oxygen in the air to sustain the combustion process.
When the jar is placed over the candle, it traps the limited air inside and restricts the flow of fresh oxygen from the surrounding environment.
As the candle continues to burn, it rapidly depletes the available oxygen within the jar.
Once there’s insufficient oxygen, the flame can no longer sustain itself and extinguishes.

Method 2: Using a burning paper strip and a test tube

Materials:

A small piece of paper
Matches or lighter
Test tube with a rubber stopper

Procedure:

Light the paper strip and quickly place it inside the test tube.
Immediately insert the rubber stopper into the test tube, sealing it.

Observation: The paper strip will stop burning shortly after being covered.

Explanation:

Similar to the jar experiment, the test tube restricts the air supply to the burning paper strip.
The limited oxygen inside the tube gets used up quickly due to the burning process.
Without sufficient oxygen, the combustion reaction cannot continue, and the flame dies out.

4. How will you show that air is dissolved in water?

Ans : Here is a captivating demonstrations you can perform to showcase the presence of dissolved air in water:

Method 1: Heating Up the H2O (Water)

Materials:

A transparent glass or beaker
Water
Stove or hot plate (optional)

Steps:

Fill the glass with water.
Optional: For a more dramatic effect, heat the water on a stove or hot plate using moderate heat. Be cautious not to boil the water.
Observe closely: As the water heats up, you’ll notice the formation of tiny bubbles rising from the bottom and sides of the glass.

Explanation:

Air is like an invisible party guest hiding in water, even at cooler temperatures. However, its fondness for the pool party diminishes as the water gets warmer.
When you heat the water, the solubility of air in it decreases. This means the water can no longer hold onto as much dissolved air as before.
As a consequence, the excess air, feeling less welcome, escapes the solution in the form of tiny bubbles that rise to the surface and eventually float into the surrounding air, making its presence known!

5. Why does a lump of cotton wool shrink in water?

Ans : Contrary to what might seem intuitive, a lump of cotton wool doesn’t actually shrink in water. It might appear to shrink, but the reason behind the observation is due to the replacement of air with water within the cotton fibers, not the cotton itself shrinking.

6. The layer of air around the earth is known as____

Ans: Atmosphere

7. The component of air used by green plants to make their food, is____

Ans : Carbon dioxide

8. List five activities that are possible due to the presence of air.

Ans :

Respiration: Living organisms, including humans and animals, use oxygen from the air for respiration, the process by which they convert nutrients into energy.
Combustion: Air, specifically the oxygen component, is essential for burning and other combustion processes.
Flight: Air allows objects to experience both lift and drag due to its buoyant force and resistance.
Sound transmission: Sound waves require a medium to travel, and air acts as the primary medium for sound propagation on Earth
Weather phenomena: Air plays a crucial role in driving various weather phenomena like wind, rain, and clouds.

9. How do plants and animals help each other in the exchange of gases in the atmosphere?

Ans : Plants and animals engage in a mutually beneficial exchange of gases in the atmosphere through their essential life processes:

1. Photosynthesis by plants:

Plants take in carbon dioxide (CO₂) from the atmosphere through tiny openings on their leaves called stomata.
Using sunlight and water, they convert CO₂ into carbohydrates (sugars) through the process of photosynthesis.
As a byproduct of photosynthesis, plants release oxygen (O₂) back into the atmosphere.

2. Respiration by plants and animals:

Both plants and animals carry out cellular respiration, a process that uses oxygen to break down food molecules and release energy.
During respiration, both organisms take in oxygen (O₂) and release carbon dioxide (CO₂) back into the atmosphere.

NCERT Solutions for Class 6 Science Chapter 11 Air Around Us

FAQ’s

What topics are covered in NCERT Solutions for Class 6 Science Chapter 11 “Air Around Us”?

The chapter covers concepts related to the composition of air, its properties, importance, and various phenomena associated with air.

How can I access NCERT Solutions for Class 6 Science Chapter 11 Air Around Us?

You can access the solutions for Chapter 11 Air Around Us online through various educational platforms or by referring to the NCERT official website.

Are the solutions provided step-by-step?

Yes, the solutions are provided in a step-by-step manner, making it easier for students to understand and follow.

Can I rely on these solutions for exam preparation?

Absolutely! The NCERT Solutions for Class 6 Science Chapter 11 Air Around Us are designed to help you prepare thoroughly for exams by providing accurate and comprehensive solutions.

How do the concepts discussed in Chapter 11 “Air Around Us” relate to environmental studies?

Chapter 11 Air Around Us explores various aspects of air, including its composition, properties, and importance in sustaining life. Understanding these concepts is vital in environmental studies as it sheds light on topics such as air pollution, climate change, and the impact of human activities on air quality and ecosystems