6th Std Science Term 3 Solution | Lesson.2 Water

Lesson.2 Water

Lesson.2 Water

I. Choose the correct answer:

1. Around 97% of water available on earth is water.

1. fresh
2. pure
3. salty
4. polluted

Ans : salty

2. Which of the following is not a part of water cycle?

1. evaporation
2. condensation
3. rain
4. distillation

Ans :  distillation

3. Which of the following processes add water vapour to the atmosphere?

1. ii and iii
2. ii and iv
3. i and iv
4. i and ii

Ans : i and iv

4. About 30% of the fresh water is found in?

1. glaciers
2. ground water
3. other sources of water
4. 0.3%

Ans : ground water

5. Using R.O. plant at home eliminates lot of non-potable water. The best way to effectively use the expelled water of R.O. plant is ___________ .

1. make the expelled water go and seep near the bore well
2. use it for watering plants
3. to drink the expelled water after boiling and cooling
4. to use for cooking as the water is full of many nutrients

Ans : use it for watering plants

II. Fill in the Blanks 

1. Only ____________ percent of natural water is available for human consumption.

Ans : 1%

2. The process of changing water into its vapour is called ________.

Ans : Evaporation

3.  ______ is built on rivers to regulate water fl ow and distribute water.

Ans : Dam

4. Water levels in rivers increase greatly during ___________.

Ans : Rainy season

5. Water cycle is also called as __________ .

Ans : Hyrdological cycle

III. True or False. If False, give the correct statement

1. Water present in rivers, lakes and ponds is unfit for use by human beings.

Ans : True

2. Seas are formed when the water table meets the land surface.

Ans : False

Cu. An. : Ground water are formed when the water table meets the land surface.

3. The evaporation of water takes place only in sunlight.

Ans : True

4. Condensation results in the formation of dew on grass.

Ans : True

5. Sea water can be used for irrigation as such.

Ans : False

Cu. An. : Surface water can be used for irrigation as such.

IV. Match the Following

V. Arrange the following statements in correct sequence

1. These vapours condense to form tiny droplets of water.

2. The water droplets come together to form large water droplets.

3. The heat of the sun causes evaporation of water from the surface of the earth, oceans, lakes, rivers and other water bodies.

4. The large water droplets become heavy and the air cannot hold them, therefore, they fall as rains.

5. Water vapour is also continuously added to the atmosphere through transpiration from the surface of the leaves of trees.

6. Warm air carrying clouds rises up.

7. Higher up in the atmosphere, the air is cool.

8. These droplets floating in the air along with the dust particles form clouds.

Ans :

3. The heat of the sun causes evaporation of water from the surface of the earth, oceans, lakes, rivers and other water bodies.

5. Water vapour is also continuously added to the atmosphere through transpiration from the surface of the leaves of trees.

6. Warm air carrying clouds rises up.

8. These droplets floating in the air along with the dust particles form clouds.

7. Higher up in the atmosphere, the air is cool.

1. These vapours condense to form tiny droplets of water.

2. The water droplets come together to form large water droplets.

4. The large water droplets become heavy and the air cannot hold them, therefore, they fall as rains.

VI. Analogy

1. Population explosion : Water scarcity :: Recycle : ______________

Ans : Water management

2. Ground water : ______________ :: Surface water : lakes 

Ans : Fresh water

VII. Give very short answer 

1. Name four different sources of water

Thus, Water from rivers,lakes and streams,ground water,desalination and rainwater harvesting are four main source of water.

2. How do people in cities and rural areas get water for various purposes?

We get water from different water sources in our surroundings. In villages / towns wells, canals, tanks, ponds, rivers, water tanks, hand pipes are the main sources of water.

3. Take out of cooled bottle of water from refrigerator and keep it on a table. After some time you notice a puddle of water around it. Why?

The cold surface of the bottle containing icy water cools the air around it and the water vapour of the air condenses on the surface of the bottle. This process is also the result of condensation of water vapour

4. We could see clouds almost every day. Why doesn’t it rain daily?

When water on the Earth’s surface is heated by the sun,it evaporates and turns into the air. Warm air can hold more moisture than cool air,so when the warmer air is cooled and the moisture condenses,it often rain more heavily.

5. Name the places where water is found as ice.

It is present in ice bergs and ice caps on top of tall mountains, galaciers and polar regions.eg:Himalayas

6. How do aquatic animals manage to live in Arctic and Antarctic Circle?

Arctic and Antarctic animals warm blooded animals and they maintain similar internal body temperature to warm blooded animals in any other climate zone-that is 35-42^oC depending on the species. They have to keep high body temperatures to remain active

7. What are the types of rain water harvesting?

Direct collection and use of rain water is called rainwater harvesting.

There are two types of rainwater harvesting.

a. Collecting water from where it falls.

(e.g): Collecting water from the roof tops of the houses or buildings (Roof water harvesting).

b. Collecting flowing rain water

(e.g): Collecting rainwater by constructing ponds with bund.

VIII. Give short answer

1. Differentiate between surface water and ground water.

Surface Water

It is found in lakes,rivers and streams and is drawn into the public water supply by intake.

Ground Water

It is located underground in large aquifers and must be pumped out of the ground after drilling a deep well.

2. Write a few slogans of your own on the topic “Save Water”.

• “Conserve water,conserve life.”
• “Don’t flush our planet’s most valuable resource.”
• “A drop of water is worth more than a sack of gold to thirsty man.”
• “Thousands Lived without love,but not without water.”

3. About 71% of earth’s surface is covered with water, then why do we face scarcity of water?

There is no change in the total quantity of water available on the earth. It remains the same. But the water useful for plants, animals and man is decreasing day by day. It is called scarcity of water.

4. Give reason for the following statement – Sewage should not be disposed of in rivers or oceans before treatment.

Sewage water include physical,biological and sometimes chemical process to remove pollutants.Its aim is to produce an environmentally safe sewage water,called efffluent,and a solid waste,called sludge or biosolid,suitable for disposal or reuse.so Sewage should not be disposed of in rivers or oceans before treatment.

5. The fresh water available on earth is only 3%. We cannot increase the amount of water. In that case, how can sustain the water level?

The main reasons for water scarcity

• Population explosion
• Uneven distribution of rainfall
• Decline of ground watertable
• Pollution of water
• Careless use of water

IX. Answer in detail

1. What is potable water? List down its characteristics.

If something is potable that means it’s safe to drink. In developed countries, tapwater is usually potable. Puddle water is not. Potable can also be a noun,meaning any drinkable liquid. The word comes from the Latin potare, meaning “to drink.”

To be considered healthy drinking water it must be:

• Cleaned of Harmful Contaminants. Including chlorine, fluoride, pharmaceutical drugs, metals (mercury, bromide, lead, arsenic), chemicals, bacteria and more.
• Replenished with Natural Minerals.
• Alkaline pH Balanced
• Great Natural Spring Water Taste.

2. Who is known as waterman of India? Browse the net and find the details about the award, the waterman received for water management. State the findings by drafting a report.

Dr. Rajendra Singh is waterman of India. He is a well-known water conservationist & environmentalist from Alwar district, Rajasthan in India.

Also known as “waterman of India”, he won the Stockholm Water Prize.

He runs an NGO called ‘Tarun Bharat Sangh’ (TBS), which was founded in 1975.

The NGO based in village horiBhikampura in Thanagazi tehsil, near Sariska Tiger Reserve, has been instrumental in fighting the slow bureaucracy, mining lobby and has helped villagers take charge of water management in their semi-aridarea as it lies close to Thar Desert, through the use of johad, rainwater storage tanks, check dams and other time-tested as well as path-breaking techniques.

Awards & Honors:

• Ramon Magsaysay Award for community leadership in 2001 for his pioneering work in community-based efforts in water harvesting and water management.
• In 2005, he got Jamnalal Bajaj Award for Application of 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, an award known as “the Nobel Prize for water”.
• In 2016, he was bestowed with Ahimsa Award by Institute of Jainology based in UK.

3. What is rainwater harvesting? Explain in a few sentences how it can be used in houses.

Direct collection and use of rain water is called rainwater harvesting.

There are two types of rainwater harvesting.

a. Collecting water from where it falls.

(e.g): Collecting water from the roof tops of the houses or buildings (Roof water harvesting).

b. Collecting flowing rain water

(e.g): Collecting rainwater by constructing ponds with bund

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