Around US

Air is present all around us

All living things need air to breathe.

Air is dense near the earth’s surface as we go up it becomes thinner

It means that the oxygen is less as we go up. This is the reason why the Mountaineers take oxygen cylinders with themVideo of

mountaineers

The envelope of air Around earth is called atmosphere. the atmosphere is divided into four layers.

1. Troposphere2. Stratosphere3. Ionosphere4. Exosphere. Video of atmosphere

Composition of airAir is a mixture of gases. The two main contents of the air are Nitrogen and Oxygen. In addition to these air also contains small quantities of Carbon- di-oxide , water vapour and traces of other gases

Nitrogen78%

Oxygen21%

Carbon-di-oxide0.03%

Other gases1%

Composition of air

Air and breathing1.All living things both plants and animals respire .2. When we breathe we take in fresh air , this is called ‘inspired air’ or ‘inhaled air’The air we breath out is called ‘expired air’ or ‘exhaled air’

Inhalation Exhalation

Video

Blood in the lungs take oxygen from the air we breathe in and carries it to all the parts of the body. Here it is used to burn food which gives energy to work and play.

I am blood.I carry

oxygen Food + oxygen = ? Energy

Plants in addition to respiration also carry out a process Called

Photosynthesis. In this process plants prepare their own food with the help of

Carbon-di-oxide Water and Sun light. During this process What released to the atmosphere?

oxygen

Photosynthesis.

Air is also necessary for burning.

Properties of air:1. Air occupies space. Ex: Air filled in the balloon,

tubes in the car.2.Air exerts pressure Ex: Syringe.3.Air has weight Ex: Inflated balloon has weight

Water has the property like all liquids to flow from a higher level to a lower level.

Working of Siphon