Samacheer Class 6 Science - Water

b. use it for watering plants

False – Water present in rivers, lakes and ponds is fit for use by human beings.
True
False – The evaporation of water takes place in any source of heat.
True
False – Sea water can not be used for irrigation as such.

The heat of the sun causes evaporation of water from the surface of the earth, oceans, lakes, rivers and other water bodies.
Water vapour is also continuously added to the atmosphere through transpiration from the surface of the leaves of trees.
These droplets floating in the air along with the dust particles form clouds.
Warm air carrying clouds rises up.
Higher up in the atmosphere, the air is cool.
These vapours condense to form tiny droplets of water.
The water droplets come together to form large water droplets.
The large water droplets become heavy and the air cannot hold them, therefore, they fall as rains.

The cooled surface of the bottle cools the air around it and the water vapour of the air condenses. So after some time, a puddle of water can be noticed around the bottle.

Floating layer of ice acts as a protective coat and does not permit heat to escape from water. So aquatic animals manage to live in Arctic and Antarctic circle.

“To a thirsty man, a drop of water is worth more than a sack of gold”.
“Water covers 2/3 of the surface of the earth. But only 0.002% is drinkable. Save water”
“Save water to secure your future”
“Don’t make nature cry, keep your water clean”
“Store water for dry days”.

71% of the earth’s surface is covered with water. The freshwater will be only 3%. It remains the same. But the water useful for plants, animals, and men is increasing day by day. So we face water scarcity.

Sewage contains harmful and toxic chemicals. They can disturb the ecosystem of the living animals, in the rivers or oceans. So it should be treated effectually before disposing into rivers or oceans.

The water which is fit for drinking by human beings is called potable water, characteristics
It is transparent.
It is odourless and colourless.
It is harmless or free from disease-causing bacteria.

The ‘Waterman of India’ is Dr. Rajendra Singh. He is a well-known water conservationist and environmentalist from Alwar district, Rajasthan.
Awards:
He gets the Ramon Magsaysay award for community leadership in 2001.
In 2005, he got the Jamnalal Bajaj Award for Science and Technology for rural development.
In 2008, The Guardian named him amongst its list of 50 people who could save the planet.
In 2015, he won the Stockholm Water Prize. He runs an NGO called ‘Tarun Bharat Sangh’ (TBS), which was founded in 1975.
In 2016, he was bestowed with Ahimsa Award by the Institute of Jainology based in UK.

Rainwater harvesting:
Direct collection and use of rainwater are called rainwater harvesting.
There are two types of rainwater harvesting.
(a) Collecting water from where it falls.
Example: Collecting water from the rooftops of the houses or buildings (Roof water harvesting).
(b) Collecting flowing rainwater.
Example: Collecting rainwater by constructing ponds with bund.

When there is no pond or lake in an area formation of clouds will be possible. Transpiration from the aerial parts of all plants and trees will evaporate water and it will form clouds.

When we breathe out, the hot air comes out from our mouth which gets condensed and changed into tiny water droplets, and glasses become wet.

northwest zone (Coimbatore, Erode, Namakkal, Karur)
b. Identify the districts that get a medium annual rainfall in Tamilnadu.
Pudhukottai, Virthunagar, Sivagangai, Salem, Dindigul, Theni, Vellore.
c. State the districts that enjoy high annual rainfall in Tamilnadu.
Tirunelveli, Kanyakumari, Chennai, Vizhupuram, Thiruvallur, Kadalur, Nagapattinam