 Water is a chemical
substance with the chemical formulaH2O. Its molecule contains one oxygen and
two hydrogen atoms connected by covalent bonds. Water is often co-exists on
Earth with its solid state ice, and gaseous state, water vapor or steam.
According to researcher’s, water covers 70.9% of the Earth's surface, and is
vital for all known forms of life. On Earth, it is found mostly in oceans and
other large water bodies, with 1.6% of water below ground in aquifers and
0.001% in the air as vapor, clouds (formed of solid and liquid water particles
suspended in air), and precipitation. Research also claims that oceans hold 97%
of surface water, glaciers and polar ice caps 2.4%, and other land surface
water such as rivers, lakes and ponds 0.6%. A very small amount of the Earth's
water is contained within biological bodies and manufactured products. Water on
Earth moves continually through a cycle of evaporation or transpiration(evapotranspiration),
precipitation, and runoff, usually reaching the sea. Over land, evaporation and
transpiration contribute to the precipitation over land. Human consumption of water:
- Drinking water
- Washing
- Chemical uses
- Recreation
- Industrial uses
- Food processing
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