We need air. We breathe air.

You cannot see air because it is colorless.

You cannot smell air because it is odorless.

Air is everywhere on planet earth.

Air covers our planet earth like a blanket. This air covers is called the atmosphere which extents to few hundred kilometers above the earth.

Take a balloon and inflate it. The balloon looks big because it is filled with air.

Moving air is called wind which blows away dry leaves and bits of paper. A strong wind can uproot trees.

The cloth tied to the boat is its sail. Air keeps pushing the sail and therefore boat moves faster. Thus exerts pressure.

Air is a mixture. What are its components?

Air is needed for burning. When the burning candle was covered with the glass, the candle burnt using up the air. The burning stopped when the air needed for burning was used up.

· We can conclude that 1/5 of air is occupied by gas which supports burning. This gas is oxygen

· When the candle burns, oxygen combines with candle wax to produce carbon dioxide and water vapor. These vapors dissolve in water creating space for the water to rise

· Thus nearly 1/5 or 20% of air is oxygen. Oxygen is a colorless gas. It supports burning. Oxygen it’s the part of air used by all living organisms for breathing

· The reaming 80% of air is mostly made up of nitrogen. Nitrogen is a colorless and odorless gas. It does not burn, nor dies it help burning. It does not dissolve in water. Air also contains small quantities of carbon dioxide, water vapor, rare gases like neon, argon, helium and dust particles.

Carbon dioxide in the air reacts with lime water turning it milky. If you leave clear lime water exposed to air for a long time it will turn white because the slow action of carbon dioxide from the air on it.

Air also contains dust particles. Flash a torch in a dark room. You will see the beam lighting up a lot of dust particles.