Air is present everywhere around us. We cannot see, touch or taste air, but we can feel it – when trees rustle, clothes on a clothes-line sway, pages of an open book flutter under a fan, or kites fly in the sky. Air is necessary for breathing and also for combustion. This chapter covers the atmosphere and its layers, the experiments that proved air is a mixture of gases, the composition of air, burning, and the importance and uses of air.
1. Air Is Everywhere
- We can live without food for some days and without water for a few hours, but we cannot survive without air for more than a few minutes.
- When air is moving it is called wind. It is cool and soothing as a breeze.
- When air moves with force it is called a storm; it can even uproot trees and blow off roof tops.
- An "empty" bottle is in fact completely filled with air. When the bottle is pushed into water in an inverted position, water does not enter, because there is no space for the air to escape. When the bottle is tilted, air comes out as bubbles and water fills the space – so air fills all the space inside the bottle.
- A weathercock shows the direction in which the air is moving at a particular place. A wind sock can also be made to find the direction of the wind.