2. AIR
A mixture of various gases such as nitrogen, oxygen, carbon
dioxide, water vapour, and a few other gases is called Air.
Air is present all around us. we cannot see it and we can only
feel its presence. For example, if we flap a hand fan near our face,
we will feel the air and if we ride a bicycle, we will feel the air
against our face.
3. Properties of Air
• Air is a very unique element of the Earth. It has many
characteristics that are its own.
• Air is colorless and transparent. This is the factor that allows us to
see through the air.
• Air lacks smell and taste.
• Air occupies the entire space in the atmosphere.
• Air has weight.
4. Uses of Air
• All living things need oxygen gas present in air to breathe.
• Plants need air to make food.
• Oxygen helps in burning. Things do not burn in the absence of
air.
• Air is used to fill tyres and balloons.
• Air helps birds fly.
• Air also helps kites fly and ships sail.
• Wind helps to run windmills.
• Air is needed for burning.
5. Air is Inhaled and Exhaled by different living organism
• Animal like humans ,cat ,dogs ,cows ,crocodiles , whales and
dolphin through lungs.
• Animals that live in water like fishes and frogs through gills.
• Insects like cockroaches, grasshoppers, caterpillars,
mosquitoes etc. have air holes called spiracles in their bodies
which help them to breathe.
• Plants breathe through tiny pores in their leaves called stomata.
6. Air Pollution
Air Pollution occurs when gases, dust, smoke, or odor
get into the air and make it unclean. Air pollution is
unsafe for humans and animals to breathe and for plants
to live with.
7. Ways to Reduce Pollution
1.Using public transports.
2.Turn off the lights when not in use.
3.Recycle and Reuse.
4.No to plastic bags.
5.Reduction of forest fires and smoking.
6.Use of fans instead of Air Conditioner.
7.Use filters for chimneys.
8.Avoid usage of crackers.
8. The effects of Air Pollution on our Health
• Air pollution causes many respiratory diseases in human as well
as animals like coughing , sneezing , headaches .
• It causes the serious diseases like lung cancer ,asthma and
bronchitis.
• Air pollution is destroying the ozone layer in the atmosphere.
10. What does air consist of? Can we see it or
smell it ? How do we know of its presence
around us?
Air is a mixture of gases. The air in earth’s atmosphere is
made up of approximately 78% nitrogen and 21 % oxygen, air
also has small amounts of other gases too such as carbon
dioxide , neon and hydrogen.
We cannot see it or smell it (but it does carry substances that
we do smell).
We cannot see air but we feel its presence. E.g. -The leaves
of the tree rustle , the clothes hanging on a clothes-line sway,
Pages of books fluttering when fan switched on etc.
11. Hook activity 1- Make a pinwheel and
observe its movement inside a room with the
fan switch off and outside in the open.
13. Hook activity 4- (fig.2.12)Take a lump of dry soil in a beaker or a
glass. Add water to it. We can see bubbles coming out from soil.
These bubbles indicate the presence of air in the soil. When the
water is poured on the lump of soil, it displaces the air which is
seen in the form of bubbles. .
14. Hook activity 4 - Take candle fix them over
two plates and light them up with a match
stick.
15. Hook Activity 5 -take a glass tumbler, a
small tennis ball and a transparent tray filled
with water .put the ball into the tray
Activity 1 Activity 2
