IS AIR PRESENT EVERYWHERE AROUND US?
Close your fist — what do you have in it? Nothing? Try the following activity to find out.
Activity
Take an empty open bottle. Is it really empty or does it have something inside? Turn it, upside down. Is something inside it, now?
Now, dip the open mouth of the bottle into the bucket filled with water as shown in Fig. Observe the bottle. Does water enter the bottle? Now tilt the bottle slightly. Does the water now enter the bottle? Do you see bubbles comingout of the bottle or hear any bubbly sound? Can you now guess what was in the bottle?
Yes! You are right. It is “air”, that was present in the bottle. The bottle was not empty at all. In fact, it was filled completely with air even when you turned it upside down. That is why you notice that water does not enter the bottle when it is pushed in an inverted position, as there was no space for air to escape. When the bottle was tilted, the air was able to come out in the form of bubbles, and water filled up the empty space that the air has occupied. This activity shows that air occupies space. It fills all the space in the bottle. It is present everywhere around us. Air has no colour and one can see through it. It is transparent.
Our earth is surrounded by a thin layer of air. This layer extends up to many kilometres above the surface of the earth and is called atmosphere. As we move higher in the atmosphere, the air gets rarer
Now can you think, mountaineers carry oxygen cylinders with them, while climbing high mountains ?