Question 1: List five activities that are possible due to the presence of air.
Answer: Five activities which are possible due to the presence of air are as follows:
Question 2: What is the composition of air?
Answer: Air is composed of nitrogen, oxygen, carbon dioxide, many other gases, water vapour and dust particles.
Question 3: Which gas in the atmosphere is essential for respiration?
Question 4: The layer of air around the earth is known as ___________.
Question 5: The component of air used by green plants to make their food, is ___________.
Answer: Carbon dioxide
Question 6: How will you prove that air supports burning?
Answer: Take a candle and try to burn it in air. Take another candle and try to burn it while keeping it submerged in water. You will observe that, while the candle burns in air; it does not burn in water. This simple activity shows that air support burning.
You may have seen rural women blowing air while lighting up the chulha. Blowing air helps in quickly burning the wood in chulha. This also shows that air supports burning.
Question 7: How will you show that air is dissolved in water?
Answer: For this, take water in a pan and start heating the water. Wait till the water begins to boil. When the water begins to boil, small air bubbles can be seen coming up from the bottom of the pan. This shows that air is dissolved in water.
Question 8: Why does a lump of cotton wool shrink in water?
Answer: Cotton wool remains fluffy because of air trapped in it. When a lump of cotton wool is dipped in water, the air goes out of the lump. Due to this, the cotton wool shrinks when dipped in water.
Question 9: How do plants and animals help each other in the exchange of gases in the atmosphere?
Answer: Plants take carbon dioxide during photosynthesis and release oxygen into the atmosphere. Animals and plants take oxygen and release carbon dioxide during respiration. Thus, both plants and animals help each other in the exchange of gases in the atmosphere.
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