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Uses of Air Pressure

We use air pressure in many ways:
1. To pull up ink into fountain pens.
2. To draw medicine into medicine dropper or
syringes.
3. Cycle, car and bus tyres are filled with air for
smooth driving.
4. To draw water using water pumps.
5. To suck the juice through straw.
6. To make hot air balloons and to rotate wind mills for grinding.

Air Pollution

Air pollution is the addition of undesired and harmful
substances in the air which can affect the health,
survival or activities of many organisms (living things),
including humans. These harmful substances are called
pollutants. The main pollutants are unburnt carbon
particles from fuels, carbon monoxide, sulphur dioxide, nitrogen dioxide and lead.
Out of these, sulphur dioxide and nitrogen dioxide gases are even more harmful. They
cause acid rain on combining with rain water or water vapour.

The Precious Water

Water is very important for our life. All living beings need water to live and survive.
About 70% of the human body consists of water.
Water is made of two atoms of hydrogen and one atom of oxygen.
Properties of Water
1. Water is a colourless, tasteless and odourless liquid.
2. It freezes at 0°C and boils at 100°C.
3. It can dissolve a large number of substances. So, it is known as universal solvent.

Aim: To study formation of solute, solvent and solution.
Materials required: Four glasses, water, spoon, salt, sugar, sand, chalk power.
Method: Take four glasses with equal amount of water. In one glass add teaspoon full of
salt and in the second add four spoons of sugar; in the third add sand and in the fourth

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