Provide general information about water $(H_2O)$.

(N/A) major part of all living organisms is made up of water. The human body contains about $65 \%$ water,and some plants contain as much as $95 \%$ water.
It is a crucial compound for the survival of all life forms.
It is a solvent of great importance.
The distribution of water over the earth's surface is not uniform. The estimated world water supply is given in the following table.
The high heat of vaporization and heat capacity are responsible for the moderation of the climate and the body temperature of living beings.
It is an excellent solvent for the transportation of ions and molecules required for plant and animal metabolism.
Estimated World Water Supply

Source	$\%$ of Total
Oceans	$97.33$
Saline lakes and inland seas	$0.008$
Polar ice and glaciers	$2.04$
Ground water	$0.61$
Lakes	$0.009$
Soil moisture	$0.005$
Atmospheric water vapour	$0.001$
Rivers	$0.0001$