The document discusses the composition and properties of air. It states that air is composed primarily of nitrogen (78%) and oxygen (21%), with smaller amounts of carbon dioxide, argon, and other gases. It notes that the sky appears blue due to the scattering of blue light by air molecules. It also explains that air contains dissolved gases and protects the Earth from temperature fluctuations. Oxygen supports respiration and combustion, while nitrogen and carbon dioxide also have important functions in plant growth and photosynthesis. The upper atmosphere contains ozone, which absorbs harmful ultraviolet rays from the Sun.

1. Block 4 – Lesson 2

3. The elements of the air scatter blue
light more efficiently than the other
colors. That’s why the sky is blue.

5. Air is dissolved in the
water of rivers, oceans,
lakes and even the soil.
It is part of the
atmosphere that
protects the Earth from
sudden temperature
changes and Sun rays.

7. Human beings breathe
the air from the lower
part of the atmosphere.
Higher parts of the
atmosphere are
abundant in Ozone (O3)
which is very important
because it absorbs
ultraviolet rays from the
Sun

9. •Air is odorless and tasteless.
•Air has volume, and it expands and compresses.
•Air has weight and presses on the surface of the
Earth. This is called Atmospheric Pressure.
•Air offers resistance that is the force that resists
motion. Human beings use this resistance for
navigation and windmills.
•Air is colorless, but when the sunlight hits the
atmosphere it appears as light blue.

10. Oxygen (21%)
21%
Carbon Dioxide (0.4%)
Nitrogen (78%)
78%
0%
Argon (0.93%)
1% Others (0.17%)
0%
AIR COMPOSITION

11. Oxygen (21%)
21%
Carbon Dioxide (0.4%)
Nitrogen (78%)
78%
0%
Argon (0.93%)
1% Others (0.17%)
0%
AIR COMPOSITION
•Oxygen: It is the
most important gas
for respiration in
living things. It also
aids combustion.

12. Oxygen (21%)
21%
Carbon Dioxide (0.4%)
Nitrogen (78%)
78%
0%
Argon (0.93%)
1% Others (0.17%)
0%
AIR COMPOSITION
•Oxygen: It is the
most important gas
for respiration in
living things. It also
aids combustion.
•Nitrogen: This gas,
combined with
oxygen, makes air
more breathable. It
supports pant
growth and it is part
of proteins in living
things.

13. AIR COMPOSITION •Carbon dioxide: Air has a
Oxygen (21%)
21%
Carbon Dioxide (0.4%)
Nitrogen (78%)
78%
0%
Argon (0.93%)
1% Others (0.17%)
0%
minimum amount of CO2.
Living organisms produce it
when they breathe. It is
needed for photosynthesis.
•Oxygen: It is the
most important gas
for respiration in
living things. It also
aids combustion.
•Nitrogen: This gas,
combined with
oxygen, makes air
more breathable. It
supports pant
growth and it is part
of proteins in living
things.

14. AIR COMPOSITION •Carbon dioxide: Air has a
•Argon: It is a noble
gas. A noble gas does
not react with other
Oxygen (21%)
21%
Carbon Dioxide (0.4%)
Nitrogen (78%)
78%
0%
Argon (0.93%)
1% Others (0.17%)
0%
minimum amount of CO2.
Living organisms produce it
when they breathe. It is
needed for photosynthesis.
•Oxygen: It is the
most important gas
for respiration in
living things. It also
aids combustion.
•Nitrogen: This gas, gases.
combined with
oxygen, makes air
more breathable. It
supports pant
growth and it is part
of proteins in living
things.