AIR, WATER, SOIL and THEIR POLLUTION
The air in our atmosphere is composed of molecules of different gases.
It consists of 78 % nitrogen gas, 21 % oxygen, 0.9 % argon, and 0.03 % carbon dioxide, water
vapor-floating molecules of water and trace gases.
Earth"s atmosphere is divided into five main layers.
Layers Ranges in km
Troposphere 0 to 12
Stratosphere 12 to 50
Mesosphere 50 to 80
Thermosphere 80 to 700
Exosphere 700 to 10000
Some Important Gases
Gases Symbol & Discovered by Fact
Oxygen (O2) O&8 Carl Wilhelm Scheele and Approximately 2/3 of the mass of the
named by Antoine human body is oxygen.
Lavoisier (1777). It is the gas we inhale.
Ozone (O3) It is a form of Christian Friedrich It is blue in color and has a strong odor.
elemental Schönbein It is very reactive gas and toxic.
Nitrogen (N2) N&7 Daniel Rutherford (1772) It is estimated at about seventh in total
and named by Jean- abundance in our galaxy and the Solar
Antoine Chaptal (1790). System.
Carbon It is a Joseph Black in 1750 It is the gas we exhale.
dioxide (CO2) compound. CO2 as a gas is heavier then air and
therefore can be layered as blanket of
It can occur in three states: solid (ice), liquid, or gas (vapor).
It is a good polar solvent and is often referred to as the universal solvent.
It covers 71% of the Earth"s surface, and is vital for all known forms of life.
Its boiling point is 1000C and freezing point is 00C.
It is tasteless and odorless.
The intrinsic colour of water and ice is a very slight blue hue, although both appear colorless in
Types of water Description pH value hardness
Soft water It is a pure form of water in which the only ion 5.5 to 7.7 0-60 gm/L
is Na+, and a natural source is rain water.
Hard water It is an impure form of water having high 7.8 as 8 > 120 gm/L
mineral contents, like Ca, Mg, sulphides,
chlorides, bicarbonates etc.
Heavy water It contains either one or both the hydrogen 7.43 -
D2O atoms in water replaced by deuterium (D). at 25 °C