Water

Correct Answer: 71%
Nearly 71% of the Earth's surface (i.e. three-fourth of the surface) is covered with water.

Correct Answer: hard water
Soap is not an effective cleansing agent when used with hard water, as the calcium and magnesium ions in the hard water form insoluble salts with soap which stick to the cloth as scum.

Correct Answer: Heavy water
Deuterium is the heavier isotope of hydrogen, and water molecule that comprises of deuterium atoms is called heavy water. 

Correct Answer: Adhesion
The capillary action of water is observed when the adhesive forces are stronger than the cohesive forces. 

Correct Answer: Surface tension
The property of surface tension is significant in water because of which, the water molecules adopt a spherical shape. 

Correct Answer: electrolysis
Electrolysis is the decomposition of a substance carried out by the passage of electric current.
The electrolysis of water yields hydrogen at the cathode and oxygen at the anode.

As water is cooled from 0^oC to 4^oC, the anomalous expansion of water takes place due to hydrogen bonding.

Water has a special association between its molecules, called hydrogen bond, because of which it shows anomalous expansion on cooling from 0^oC to 4^oC. Hence, the density of water is maximum at 4^oC.

Correct Answer: Evaporation
When the wet clothes are spread out, the water molecules absorb heat from the surroundings and escape into the atmosphere. This processs is called evaporation.