1) How will you show that air is dissolved in water?
2) Why does a lump of cotton wool shrink in water?
3) The layer of air around the earth is known as………………….
4) The component of air used by green plants to make their food, is………………….
5) List five activities that are possible due to presence of air.
6) How do plants and animals help each other in exchange of gases in the atmosphere?
Answers
Answer:
1.) Take some water in a glass vessel or beaker. Heat it slowly on a tripod stand. Before the water begins to boil, look carefully at the inner surface of the vessel. You will see tiny bubbles on the inside. On heating, air dissolved in water escapes in the form of these bubbles.
2.)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.
3.) Atmosphere
4.) carbon dioxide gas
5.) Five activities which are possible due to the presence of air are as follows:
Burning something.
Winnowing.
Flying kite.
Movement of firkin (toy windmill)
A ship moving because of sail.
6.) Animals, during respiration, take in oxygen and release carbon dioxide gas. Plants, on the other hand, utilize this carbon dioxide gas in the process of photosynthesis to produce food and release oxygen in the atmosphere.