Class 6 Science Chapter 15 Air Around Us Extra Questions and Answers

CBSE Class 6 Science Chapter 15 Air Around Us Extra Questions and Answers is available here. Students can learn and download the PDF of these questions for free. These extra questions and answers are prepared by our expert teachers as per the latest NCERT textbook and guidelines. Learning these extra questions will help you to score excellent marks in the final exams.

Air Around Us Class 6 Science Extra Questions and Answers

Very Short Answer Questions

1. Name the main component of air.
Answer: Nitrogen gas

2. What is the source of oxygen gas in air?
Answer: Photosynthesis by green plants is source of oxygen gas in air.

3. What is the percentage of nitrogen in air?
Answer: 78.1%

4. What is the percentage of oxygen in air?
Answer: 20.9%

5. What is the source of carbon dioxide in air?
Answer: Respiration by animals and plants and burning of fuel.

6. Mention one necessary condition for the combustion to take place.
Answer: Presence of air.

7. Define atmosphere.
Answer: The blanket of air that surrounds the earth is called atmosphere.

8. What is humidity?
Answer: The amount of water vapour present in the air is called humidity.

9. Which gas is most abundant and is important for growth of plants and animals?
Answer: Nitrogen

10. Name the component of air used by green plants to make their food.
Answer: Carbon dioxide

11. Name any two musical instruments in which air plays an important role.
Answer: Flute and saxophone

Short Answer Type Questions

1: What happens when air comes in contact with a cool surface?

Answer: When air comes in contact with a cool surface, it condenses and drops of water appear on cool surface.

2: Why do you think mountaineer carry oxygen cylinders with them, while climbing high mountains?

Answer: There is less oxygen at high places like mountains, so they carry oxygen cylinder with them to breathe there.

3: Why you feel suffocation in a closed room, where some material is burning?

Answer: Burning of some material releases smoke that contains few gases and fine dust particles that is harmful, thus we feel suffocation in a closed room, where some material is burning.

4: Why there are long chimneys in factories?

Answer: Chimneys take the harmful gases and smoke of factories away from our noses.

5: Air is necessary for combustion. Explain the statement.

Answer: Fix two candles in middle of a container containing water. Light both candles. Now cover the candles with an inverted transparent glass, you will observe that candles goes off. This happens because of absence of air. Thus, we can say that air is necessary for combustion.

6: Air occupies space. Explain the statement.

Answer: Blow a balloon, air from your body enters balloon at it gets bigger because air occupies space.

7: When the open mouth of an empty bottle is tilted in a bucket filled with water, we see bubbles coming out of it. Explain the phenomenon.

Answer: The bottle contains air so when it was titled air came out in the form of bubbles.

8: What is air made up of?

Answer: Air is made up of mixture of gases like – Nitrogen, oxygen, carbon dioxide, water vapour, dust particles and other gases.

9: Air contains dust particles, while inhaling air we also inhale dust particles. Give reason in support of the statement, whether it is true or false?

Answer: False, because our nose contains fine hair and mucus that trap all dust particles and prevent its entrance inside our body.

10: Why we should not breathe through our mouth?

Answer: If we will breathe through our mouth then dust particles present in air will enter our body and will cause harmful diseases.

11: Draw a diagram showing composition of air in atmosphere.
Answer:

12: How does an organism living in soil breathe?

Answer: Through air present in soil.

13: How can you show that air is dissolved in water?

Answer: Take water in a pan and heat it. After sometimes just before it boils we can observe some bubbles at the inner surface of the pan. This is because of the air dissolved in water.

14: Why an animal living in soil does, comes out of soil for respiration in rainy season?

Answer: When it rains heavily, water fills up all the spaces occupied by the air in the soil. Therefore, organism living in soil has to come out for respiration.

15: Why does a lump of cotton wool shrink in water?

Answer: A lump of cotton wool shrinks in water because water filled up the empty space that the air has occupied.

16: List at least five activities that are possible due to the presence of air.

Answer: Respiration, burning, photosynthesis, movement of aeroplane and parachutes, generation of electricity by windmills.

17. Why is air considered as a mixture?

Answer: Air contains oxygen and nitrogen as its major constituents of air. These gases retain their properties in air. So, the air is called a mixture.

18. Name the major gas present in the (a) inhaled air (b) exhaled air.

Answer: (a) Oxygen
(b) Carbon dioxide.

19. Write the necessary conditions for rusting of iron to take place.

Answer: Rusting of iron takes place in the presence of moisture and air. So, the presence of air and water vapour in air are two necessary conditions for rusting of iron.

20. Name a device which uses wind energy to generate electricity.

Answer: Windmills use the wind energy to convert wind energy into electrical energy

21: What is wind energy? Mention its two advantages.

Answer: Blowing air is called wind. Wind possesses kinetic energy. The kinetic energy possessed by wind is called wind energy.

Uses of Wind Energy are:
(i) Wind energy is used to pump the ground water.
(ii) Wind energy is used to generate electricity with the help of windmills.

22. Mention two uses of air.

Answer: The two uses of air are as below:
(a) For respiration all organisms need air.
(b) For burning of any substance air is needed.

23. What happens if the percentage of oxygen in the air reaches to 70%?

Answer: If any substance catches fire it will become difficult to extinguish the fire, as oxygen supports combustion.

24. Why is carbon-dioxide gas used to extinguish fire?

Answer: It is because carbon-dioxide does not support combustion. When sprayed on burning object it stops the supply of oxygen and extinguishes fire.

25. How will you prove that soil contains air in it?

Answer: Take a glass tumbler add some soil in it, then pour some water on the soil slowly, the air-bubbles comes out of the soil. This proves that soil holds air in it.

26. Why do we see the sky and air clear and clean after rainfall?

Answer: The dust particles which remain suspended in air get loaded and come down on the ground due to rainfall, this is the reason that the sky and the air look clean and clear after rainfall.

27. Explain why mountaineers carry oxygen cylinders with them?

Answer: As you go up, above the sea-level the atmospheric pressure goes on decreasing and the amount of oxygen also decreases at higher altitude.

28. Explain why during an incident of fire, one is advised to wrap a woollen blanket over a burning object.

Answer: Blanket cuts the supply of oxygen to the object that is burning, thereby prevents it from further burning.

29. Why does the transparent glass of windows, if not wiped off regularly, appears hazy?

Answer: Air contains dust and smoke along with the gases. These gets deposited on the glass windows and make them appear hazy.

30. Why during an incident of fire, one is advised to wrap a woollen blanket over a burning object?

Answer: For combustion to take place, oxygen is required. When a woollen blanket is wrapped over a burning object, fire loses contact with oxygen and, therefore, stops burning after sometime.

31. Why do you think, mountaineers carry oxygen cylinders with them, while climbing high mountains?

Answer: As we go higher on the mountains, the air becomes thinner. The amount of oxygen decreases and it becomes hard to breath. Therefore, mountaineers carry oxygen cylinders with them.

32. How do the organisms living in soil get the air they need, for respiration?

Answer: The spaces between the soil particles are filled with air. This air is taken up by plants and animals for respiration.

33. Why are factories fitted with tall chimneys?

Answer: Burning of fuel and materials produce smoke and other harmful gases which are released out of the factories by the chimneys.

Long Answer Type Questions

1: How do plants and animals help each other in the exchange of gases in the atmosphere?

Answer: Plants and animals help each other in the exchange of gases in the atmosphere Plants take carbon dioxide to prepare food and release oxygen during daytime. This oxygen is taken in by animals and carbon dioxide is released. Thus, plants and animals help in maintaining balance of oxygen and carbon dioxide.

2: Explain the role played by air in the life of human, animals and plants.

Answer: Living things cannot live without air. We can survive on planet earth because of atmosphere only. Plants cook their food by the process of photosynthesis because of air only. They use carbon dioxide gas of air and releases oxygen that is utilized by human and animals to breathe in. Air is necessary for combustion, flying of aeroplanes and birds. Thus, it is well said Air is life.

3. Describe balance of oxygen in the air.

Answer: The oxygen in air is used by the organisms present in air, water or soil or on earth for their respiration. During respiration carbon dioxide gas is released to air. But green plants during photosynthesis use carbon dioxide of air for preparing food and they release oxygen gas in the air. Thus, the balance of oxygen in air is maintained.

4. What happens if the percentage of carbon-dioxide increases in the air?

Answer: The increased percentage of carbon-dioxide will cause green house effect, i.e. it will not allow the hot rays of sun to escape from the atmosphere after reflection once they enter the earth’s atmosphere, thereby increasing the temperature of earth, ice on mountains will melt and water level will rise.

5. You must have seen during rainy season, when it rains the animals like earthworm, snakes, snails etc. are commonly seen. Explain why?

Answer: All these animals live in underground burrows or remain buried in the soil. They get oxygen from air that enters into the burrow through entrance of burrow or through pores in the soil. But when it rains, the water gets filled in their dwelling places and pores of the soil. So, they come out in search of air.

6. Why all the oxygen of atmosphere does not get used up though a large number of organisms are consuming it?

Answer: A large number of organisms take up oxygen for respiration and release carbon dioxide. Plants take up this carbon dioxide and release oxygen in the atmosphere. Therefore, this balance is maintained.

7. How will you prove that oxygen supports burning?
Answer:

• Take three candles, two glass jars that can cover two candles but of different sizes and a watch.
• Light all the three candles at one time after fixing them on the table. Cover two candles with the jars. Leave one candle uncovered. Switch off the fan and close doors and windows. This will stop wind from blowing off the candles.
• After some time the candle covered with the small jar goes off first. Then the one with a bigger jar goes off. The candle in the open continues to burn. Thus, air supports burning.

8. How will you show that air is dissolved in water?
Answer:

• Take some water in a glass vessel. Look carefully at the inner surface of the vessel.
• There are tiny bubbles on the inside of the vessel. These bubbles come from the air dissolved in water.
• Heat the water slowly on a tripod stand.
• We see the air dissolved in it escapes. On further heating, the water itself turns into vapour and finally begins to boil.

Thus, the animals living in water use the dissolved oxygen in water.

9. How is the level of oxygen maintained in the atmosphere?

Answer: The level of oxygen is maintained in the atmosphere by planting more and more trees and by avoiding excessive burning of fuels. The plants will take up the carbon dioxide in the atmosphere to make their food and in turn will release oxygen. This oxygen is taken up by animals, including humans, for respiration and in turn release carbon dioxide.