Presence of air around us

Air is present everywhere around us. It fills all the empty space. It has no colour and one can see through it. It is transparent.

The presence of air can be felt by a simple experiment.

AIM  : To show presence of air around us
Material required : (i) Empty bottle (ii) Beaker (iii) Water
Mathod :  Take an empty glass bottle. Turn it upside down. Now dip the open mouth of the bottle into a bucket filled with water as shown in the figure. We observe that water does not enter the bottle.
Now tilt the bottle slightly. We observe that now water enters the bottle and we can see bubbles coming out of the bottle with a bubbly sound.
This shows that air was present in the bottle. The bottle was not empty at all. In fact it was filled completely with air even when it is upside down. That is why 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.