NCERT Solutions: Air Around us Notes | Study Science Class 6 - Class 6

Class 6: NCERT Solutions: Air Around us Notes | Study Science Class 6 - Class 6

The document NCERT Solutions: Air Around us Notes | Study Science Class 6 - Class 6 is a part of the Class 6 Course Science Class 6.
All you need of Class 6 at this link: Class 6

Q.1. What is the composition of air?
Ans. Air is a mixture of nitrogen, oxygen, carbon dioxide, water vapours, and some other gases. It also contains dust particles. By volume, dry air contains 78.09% nitrogen, 20.95% oxygen, 0.93% argon, 0.04% carbon dioxide, and small amounts of other gases. Air also contains a variable amount of water vapour, on average around 1% at sea level, and 0.4% over the entire atmosphere.

Q.2. Which gas in the atmosphere is essential for respiration?
Ans. Oxygen gas in the atmosphere is essential for respiration.
Respiration is defined as a metabolic process wherein, the living cells of an organism obtains energy (in the form of ATP) by taking in oxygen and liberating carbon dioxide from the oxidation of complex organic substances.
Aerobic respiration: It is a type of cellular respiration that takes place in the presence of oxygen to produce energy. It is a continuous process that takes place within the cells of animals and plants.
Anaerobic respiration: It is a type of cellular respiration that takes place in the absence of oxygen to produce energy. In all green plants, cellular respiration takes place in the mitochondria of the cell in the presence of oxygen.

Q.3. How will you prove that air supports burning?
Ans. To prove that air supports burning, let's take two lighted candles.
(i) Put one candle in a tumbler containing water and cover it with an inverted glass.
(ii) Put the second candle in open air. After some time, this covered candle gets extinguished and the water level rises up in the glass.
(iii) This happens because oxygen present inside the air in the glass was used up completely.
This experiment shows that air is necessary for burning.
Practical life example: In villages, the food is cooked on chulha. In the chulha , blowing air helps in quickly burning the wood in it. This also shows that air supports burning.

Q.4. How will you show that air is dissolved in water?
Ans. Take some water in a glass vessel or beaker. Heat it slowly on a tripod stand. Look carefully at the inner surface of the vessel, before reaching its boiling point, the bubble of air start rising from bottom to surface. These bubbles come from the air dissolved in water.
NCERT Solutions: Air Around us Notes | Study Science Class 6 - Class 6

Water contains air


Q.5. Why does a lump of cotton wool shrink in water?
Ans. A lump of cotton wool has a lot of air trapped inside the space present in its fibers. When this lump of cotton is immersed in water, all the air is replaced by water. Due to this, the cotton lump shrinks down.

Q.6. The layer of air around the earth is known as _______.
Ans. The layer of air around the earth is known as the atmosphere.  Atmosphere consists of various gases such as Nitrogen, Oxygen, etc.  

Q.7. The component of air used by green plants to make their food, is _______.
Ans. The component of air used by green plants to make their food, is carbon dioxide. 
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.

  • Natural sources of carbon dioxide include most animals, which exhale carbon dioxide as a waste product.
  • Human activities that lead to carbon dioxide emissions come primarily from energy production, including burning coal, oil, or natural gas.    

Q.8. List five activities that are possible due to the presence of air.
Ans.
(i) Living beings use air for respiration.
(ii) Plants use air (carbon dioxide) to prepare their food.
(iii) Blowing air (wind) is used for power generation by windmills.
(iv) Air helps in burning of fuels and substances.
(v) Air helps in the scattering of seeds and pollens of plants.
(vi) Air helps in the movements of sailing yachts, gliders, parachutes and airplanes.


Q.9. How do plants and animals help each other in the exchange of gases in the atmosphere?
Ans. Animals, during respiration, take in oxygen and release carbon dioxide gas. Plants, on the other hand, utilise this carbon dioxide gas in the process of photosynthesis to produce food and release oxygen in the atmosphere. Thus, we can say that plants and animals help each other in exchange for gases in the atmosphere.

  • External respiration is the exchange of gases with the external environment, and occurs in the alveoli of the lungs.
  • Internal respiration is the exchange of gases with the internal environment, and occurs in the tissues.
  • The actual exchange of gases occurs due to simple diffusion.
The document NCERT Solutions: Air Around us Notes | Study Science Class 6 - Class 6 is a part of the Class 6 Course Science Class 6.
All you need of Class 6 at this link: Class 6

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