22 March is World water day. UN recommends 50 liters of water per person per day. 2003 was the international year of freshwater observed by the UN. 2005-2015 was the international decade for action on WATER FOR LIFE.71 % of earth is covered with water.
Temporary hardness of water is due to calcium and magnesium hydrogen carbonates. It can be removed by boiling and addition of lime. This converts them to carbonates and hydroxide which are soluble.
Permanent hardness is due to presence of Magnesium and calcium chlorides and sulphates it is treated using washing soda.
Aquifers
are underground water resources where water is stored
between rock layers.
Oceans – 97% |
Polar ice caps – 2% |
Ground water – 0.61% |
Lakes - 0.009% |
Saline lakes and inland sea – 0.008% |
soil moisture – 0.005% |
Water vapor – 0.001% |
rivers – 0.0001% |
TABLE 1: WATER SUPPLY
During
fires we must wrap a woolen blanket over a burning object
to cut off the supply of air to it
During heavy rains, water flows into soil and covers all air pockets so earthworms rise to the surface to breathe.
Hydrogen peroxide is used as a bleaching agent, treating industrial effluents and pollution control.
Eucalyptus trees should be planted along sewage lines as these absorb wastewater and release water vapor into the atmosphere.
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