Every day, we experience a lot of things in and around us. One such experience is the air around us. Air is almost everywhere on the earth. It is still a topic of debate , when did the Earth's atmosphere filled with a complete air? What was it like at the time of evolution of atmospheric air? However, it is beyond the scope of this lesson as we will be covering some fundamental question answers in the different aspects of air.
Textbook Questions
1. What is the composition of air?Answer: Air is a mixture of water vapour, oxygen, nitrogen. Air has some pollutants such as carbon dioxide, dust and smoke.
2. Which gas in the atmosphere is essential for respirationAnswer: All animals including humans need oxygen found in the atmosphere .
3. What are the properties of air?Answer: Air is a gaseous mixture having the following characteristics:
4. How will you prove that air supports burning?
Answer:Take 2 lighted candles and keep them inside a glass jar in a standing position. Invert a tumbler in one of the candles , so that air doesn't move inside. We see that the candle covered with the glass tumbler will be shut off after some time, whereas the other candle continued burning. This shows that , all the available oxygen found in the inverted jar was used up and once the air gets over, the flame got extinguished. Since the other candle is getting a continuous supply of air. It keeps burning until the fuel is over.
5. Which gas is used by fireman as an extinguisher agent? Why?
Answer: Carbon dioxide is used by the fireman as it doesn't support burning. I. Other words, it behaves exactly opposite to the oxygen gas.
6. How will you show that air is dissolved in water?
Answer:Keep some water in a container which is fixed to a stand. Start heating the container, observe the inner surface of the vessel. What is visible? We observe tiny bubbles inside. Which shows that , on heating water pushes the oxygen bubbles onto the top surface to escape from the container. This experiment shows that air is present in the water.
7. What is vacuum? Give examples.
Answer: Vacuum is a state of absence of air in a given space. This sometimes create a negative pressure. Vacuum cleaner is the best example for this.
8. Why does a lump of cotton wool shrink in water?
Answer: The cotton lump shrinks when dipped in water due to the escape of air inside the cotton lump
9. Is air present everywhere around us?
Answer: Yes air is found everywhere however, beyond the layers of atmosphere, air is absent.
10. What happens to the air during summer?
Answer: Air becomes light on heating due to summer. This allows hot air moves upward towards the clouds. Followed by this, rainy season begins.
11. List any five activities that are possible due to air.
12. What is symbiosis? How do plants and animals help each other in the exchange of gases in the atmosphere?
Answer:Symbiosis is the law of nature. It is defined as the dependency of plants and animals on each other. During the respiration, animals consume oxygen from the air and release carbon dioxide gas into the air while green plants do the opposite by consuming carbon dioxide and releasing oxygen which is necessary for us .
13. Why is oxygen low at high altitudes ( mountains or hills)
Answer: Oxygen levels are lower at high altitudes because the air pressure decreases as you go higher. Although the percentage of oxygen in the air remains the same (about 21%), the lower pressure results in fewer oxygen molecules per breath. This makes it harder for your body to get enough oxygen, which can lead to altitude sickness in some cases..
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