Water is getting polluted:
(i) By industrial waste
(ii) By human activities
Measures to stop water pollution:
(i) We should not throw waste materials and garbage into water.
(ii) We should sensitize people about harmful effects of water pollution.
Associated Value : We should discourage any activity in our life that may cause water pollution

Areas covered with concrete affect the availability of groundwater because concrete reduces the seepage of rainwater into the ground which leads to reduction in the availability of groundwater.

There is a need for conserving water because of the following reasons
(i) Increasing population is creating more demand for usable water.
(ii) Availability of freshwater is decreasing day-by-day.

Water kept under the shade of a tree also evaporates because moving air gets heated from sunlight. This warm air provides heat for evaporation of water kept in the shade.

Wet clothes placed on a clothes line dry after sometime because water present in wet clothes is converted into water vapour and released in atmosphere due to evaporation which leaves them dry.

In this process, the rain water is collected from the rooftop to a storage tank, through pipes. This water may contain soil from the roof and need filtering before it is used. Instead of collecting rain water in the tank, the pipes can go directly into a pit in the ground. This then seeps into the soil to recharge the ground water.

Water is used:
(i) for drinking and cooking
(ii) for bathing and cleaning.
(iii) in agriculture, to produce food.
(iv) in Industries, to perform different activities

Sea water reaches a lake or pond is represented by a diagram:

The climate close to the earth's surface is warm. It gets cooled as one go up in atmosphere. Water vapour being lighter, rises up in the atmosphere. At the upper layer of atmosphere, where the temperature is lower the vapour get condensed into tiny water droplets and forms cloud.

Yes, cutting of trees are responsible for droughts and floods. Cutting of trees disrupts the natural water cycle. trees are natural water tanks. They absorb water during rain. When we cut trees, water can't be absorbed, so it has to go where gravity takes it, which causes flood. Deforestation and soil erosion would dry up the place where it happens, since water isn't absorbed. This causes drought.

Some water pipes burst in winters because during winter, cold develops enormous pressure in the pipes and due to this high pressure, water pipes burst.

Wet clothes placed on a clothesline get dry after some time due to evaporation. In this process, water present in wet clothes is converted into water vapour which is released into atmosphere .

Water from the oceans and surface of the earth goes into air as vapours and returns as rain, hail or snow and finally goes back to the oceans. The circulation of water in this manner is known as water cycle. The circulation of water between ocean and land is a continuous process. It maintains the supply of water on land.

We can conserve water by following ways:
(i) Do not waste water and repair all the leaking water taps.
(ii) Do not use drinking water in garden or in cleaning.
(iii) Do not throw any waste in ponds or rivers to prevent their pollution

Engines release large amount of heat. This heat gets consumed in the conversion of water (present in radiator ) into water vapours , therefore engine  parts do not heat up.

Water is called the universal solvent because it dissolves most of the salts and substances in it.

Lakes and ponds are formed by the collection of rain water in low lying areas and leakages from the ground water reserves also add water to it.

Oxygen is slightly soluble in water. Fish and aquatic plants need oxygen to survive and they inhale this dissolved oxygen for their survival

For marine life, ocean is most important and vital. It provides them habitats and it is the source of oxygen. Without oxygen they won't be able to breathe, move and will die

Water is the medium by which plant sucks all necessary minerals from soil , takes food to various parts and absorbs oxygen. Water is also necessary for photosynthesis

If water reaches earth in the frozen form, it is called hail

Yes, oxygen is soluble in water. This is the source of oxygen supply for aquatic habitats.

Water evaporates from sea, lakes and other water surfaces. Water also evaporates from wet lands, clothes, etc. Water also evaporates from plants through transpiration.

Water from the ocean and surface of earth goes into air as vapour through evaporation and transpiration where it cools down and forms tiny water droplets through condensation. These then turn into clouds and returns as rain