NCERT Revision Notes for Chapter 14 Water Class 6 Science
CBSE NCERT Revision Notes1
Answer
- Water and forms of water
- Uses of water
- Sources of water
- Water cycle
- Rain water harvesting
- Scarcity of water
2
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→ Water is a natural resource which is vital for both plants and animals. It is made up of tiny molecules oxygen and hydrogen.
→ Earth surface is covered with water is about three-fourth in ratio. That is why earth is known as water planet.
3
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(i) Solid: ice which is found at the poles of the earth. The glaciers and snow covered mountains is solid form of water.
(ii) Liquid: rivers, lakes, seas and oceans are liquid form of water.
(iii) Gas: water vapour is present all around us.
4
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5
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6
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→ It is a prime source of water.
→ Physically rain water is clear, sparkling and bright.
→ Bacteriologically rain water is free from pathogenic agents.
→ Chemically it is very soft containing traces of dissolved solids.
7
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→ It is originate from rain water. It is main source of water supply in many areas.
→ It is prone to contamination from animal and human sources.
→ It needs to purify before use.
→ Example: lakes, river, tanks etc.
8
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→ It is the cheapest and most practical means of providing water to small communities.
→ It is superior to surface water because the ground itself provides an effective filtering medium.
9
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→ It is a continuous circulation of water in nature is called water cycle.
• It consists in three processes:
(i) Evaporation: it is a conversation of liquid into vapour is called evaporation.
(ii) Precipitation: it is falling down of water from clouds is called precipitation.
(iii) Runoff: it is a process in which the water of the land usually reaching the sea.
10
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→ It is a way to increase the availability of water to collect rainwater and store it for later use.
→ Collection of rain water in this way is called rain water harvesting.
→ Rooftop rain water harvesting: the rain water is collect from the rooftop to a storage tank, through pipes.
→ Other option is to allow water to go directly to the ground from the roadside drains that collect rainwater.
11
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→ It is a situation where there is insufficient water to satisfy normal requirements.
• The factors of scarcity of water are:
→ Increasing industries
→ Agricultural activities
→ Increasing population
→ Deforestation