Samacheer Kalvi 6th Science Solutions Term 3 Chapter 2 Water

Tamilnadu Samacheer Kalvi 6th Science Solutions Term 3 Chapter 2 Water

Samacheer Kalvi 6th Science Water Textual Evaluation

I. Choose the appropriate answer :

Question 1.
Around 97% of water available on earth is _______ water.
(a) fresh
(b) pure
(c) Salty
(d) polluted
Answer:
(c) Salty

Question 2.
Which of the following is not a part of water cycle?
a. evaporation
b. condensation
c. rain
d. distillation

Question 3.
Which of the following processes add water vapour to the atmosphere?
i. Transpiration
ii. Precipitation
iii. Condensation
iv. Evaporation
(a) ii and iii
(b) ii and iv
(c) i and iv
(d) i and ii
Answer:
(c) i and iv

Question 4.
About 30% of the freshwater is found in?
a. glaciers
b. groundwater
c. other sources of water
d. 0.3%
Answer:
b. groundwater

Question 5.
Using R.O. plant at home eliminates a lot of non-potable water. The best way to effectively use the expelled water of R.O. plant is _______
(a) make the expelled water go and seep near the bore well
(b) use it for watering plants
(c) to drink the expelled water after boiling and cooling
(d) to use for cooking as the water is full of many nutrients
Answer:
(b) use it for watering plants

 

II. Fill in the blanks :

1. Only _______ percent of natural water is available for human consumption.
2. The process of changing water into its vapour is called _______
3. _______ is built on rivers to regulate water flow and distribute water.
4. Water levels in rivers increase greatly during _______
5. Water cycle is also called as _______

Answer:

1. 0.3
2. Evaporation
3. Dam
4. Raining
5. Hydrological cycle

 

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

Question 1.
Water present in rivers, lakes and ponds is unfit for use by human beings.
Answer:
False. Water present in rivers, lakes and ponds is fit for use by human beings.

Question 2.
Seas are formed when the water table meets the land surface.
Answer:
False. Ponds are formed when the water table meets the land surface.

Question 3.
The evaporation of water takes place only in sunlight.
Answer:
True.

Question 4.
Condensation results in the formation of dew on grass.
Answer:
True.

Question 5.
Sea water can be used for irrigation as such.
Answer:
False. Sea water cannot be used for irrigation as such.

 

IV. Match the following :

1. Flood	Lake
2. Surface water	Evaporation
3. Sunlight	Water vapour
4. Cloud.	Pole
5. Frozen water	Increased rainfall

Answer:

1. Flood	Increased rain fall
2. Surface water	Lake
3, Sunlight	Evaporation
4. Cloud	Water vapour
5. Frozen water	Pole

 

V. Arrange the following statements in the 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.

Answer:

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

 

VI. Analogy:

Question 1.
Population explosion : Water scarcity :: Recycle : __________
Answer:
Water Management.

Question 2.
Ground water : __________ :: Surface water : lakes
Answer:
Tube wells

VII. Give Very Short Answer:

Question 1.
Name four different sources of water.
Answer:
Rivers, wells, lakes, glaciers, ponds etc.

Question 2.
How do people in cities and rural areas get water for various purposes?
Answer:
In city, people get water from water tanks, hand pipes and bore wells.
In rural area, people get water from wells, canals, ponds and rivers.

Question 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?
Answer:
The cooled surface of 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.

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

1. The millions of tiny droplets do not collide with another to form larger droplets.
2. The air around the clouds is not cool.

Question 5.
Name the places where water is found as ice.
Answer:
Polar ice-caps, Ice sheets and glaciers in Artie region arid Antarctica.

Question 6.
How do aquatic animals manage to live in Arctic and Antarctic Circle?
Answer:
In Arctic and Antarctic circle, water in lakes and ponds will be frozen and a solid layer of ice is formed on the surface of water. Still aquatic animals living under the ice do not die. This is because the floating layer of ice acts as a protective coat and does not permit heat to escape from water. So as the surface water alone turns to ice, the aquatic animals manage it.

Question 7.
What are the types of rainwater harvesting?
Answer:
There are two types of rainwater harvesting.

1. Collecting water from where it falls.
2. Collecting rainwater by constructing bunds.

 

VIII. Give Short Answer:

Question 1.
Differentiate between surface water and groundwater.
Answer:
Surface water:

1. Water present on the surface of the earth.
2. Ex : River, lake, ponds, streams or freshwater.

Groundwater:

1. Water present beneath earth’s surface in soil.
2. Ex : open wells, tube wells (or) hand pumps, Spings etc.

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

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

Question 3.
About 71% of earth’s surface is covered with water, then why do we face scarcity of water?
Answer:
About 71% of the earth’s surface is covered with water and even then we face scarcity of water. Reasons:

1. 97% of total water is found in seas and oceans, which is salty and not fit for human consumption.
2. Only 3% found is the freshwater and that too available in polar ice caps and glaciers.
3. Out of 3% fresh water, only 0.3% is available to us as surface water, in lakes, rivers, and swamps.

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

1. Sewage should not be disposed of in rivers or oceans before treatment.
2. If we dispose of sewage before treatment the rivers and oceans will be polluted.
3. Aquatic animals and species will die due to pollution.
4. We can not use the river water for our day to day life.

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

1. The sewage water treatment is to be adopted.
2. Decrease the usage of pesticides, insecticides, and fertilizers in agriculture.
3. Protect forest and trees.
4. Adopt drip irrigation and sprinkler irrigation in agriculture.
5. Rainwater harvesting should be implemented in every building.
6. Create awareness about the impact of throwing wastes into the water bodies.

 

IX. Answer in detail:

Question 1.
What is potable water? List down its characteristics?
Answer:

1. Potable water is the water which is safe to drink.
2. On average the human body requires 2-3 litres of water per day for proper functioning.

Characteristics of potable water :

1. Cleaned of harmful contaminants.
2. It is transparent.
3. It is odourless and colourless.
4. It is harmless or free from disease-causing bacteria.

Question 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.
Answer:
The ‘Waterman of India’ is Dr. Rajendra Singh. He is a well-known water conservationist and environmentalist from Alwar district, Rajasthan.

Awards:

1. He get Ramon Magasaysay award for community leadership in 2001.
2. In 2005, he got Jamnalal Bajaj award for Science and Technology for rural development.
3. In 2008, The Guardian, named him amongst its list of 50 people who could save the planet.
4. In 2015, he won Stockholm Water Prize. He runs an NGO called ‘Tarun Bharat Sangh’ (TBS), which was founded in 1975.
5. In 2016, he was bestowed with Ahimsa Award by Institute of Jainology based in UK.

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

1. Direct collection and use of rain water is called rainwater harvesting.
2. The system is easy to install, operate and maintain for all types of houses.
3. Excellent and valuable source of water in emergencies.
4. Reduces rainwater runoff and solve drainage problems in houses.
5. Ideal solution for inadequacy of water.
6. Increase groundwater level.

 

X. Questions based on Higher Order Thinking Skills :

Question 1.
When there is no pond or lake in an area, will there be the formation of clouds possible in that area?
Answer:
Yes, the formation of clouds is possible at that area because plants also release water vapour by transpiration process. This water vapour will form clouds.

Question 2.
To clean the spectacles, people often breathe out on glasses to make them wet. Explain why do the glasses become wet.
Answer:
When we breathe out, the hot air comes out from our mouth which get condensed and changed into tiny water droplets and glasses become wet.

 

XI. Crossword :

DOWN:
1. A method of water conservation.
2. Process of getting water vapour from sea water.
6. Water stored in dams is used for generation of _____
ACROSS
3. _______ is a large body of non-potable water found in nature.
4. In summer, the body loses water as _______
5. Plants undergo _______ and contribute to water cycle.

Answer:
Down:
1. Recycling
2. Evaporation
6. Electricity

Across:
3. Ocean
4. Sweat
5. Transpiration

 

XI.

Question 1.
Observe the given graph carefully and answer the questions.

a. What percentage of water is seen in fish?
b. Name the food item that has maximum amount of water in its content.
c. Name the food item that has minimum amount of water in its content.
d. Human body consists of about _________ percentage of water.
e. Specify the food item that can be consumed by a person when he/she is suffering from dehydration.
Answer:
a. 70% of water is seen in fish.
b. Watermelon has maximum amount of water in its content.
c. Fish has minimum amount of water in its content.
d. 60%.
e. Watermelon is the food item which can be consumed by a person when he/she is suffering from dehydration.

Question 2.
Look at the map of Tamilnadu showing annual rainfall and answer the questions given below.

a. Identify the districts that get only low annual rainfall in Tamilnadu.
b. Identify the districts that get a medium annual rainfall in Tamilnadu.
c. State the districts that enjoy high annual rainfall in Tamilnadu.
Answer:
a. Dharmapuri, Erode, Karur, Trichy, Perambalur, Tanjore, Pudukottai, Dindugul, Madurai, Sivagangai, Ramanathapuram.
b. Thiruvallur, Chennai, Kanchipuram, Vellore, Krishnagiri, Thiruvannamalai, Salem, Namakkal, Vizhupuram, Ariyalur, Thiruvarur, Thiruppur, Virudunagar, Tuticorin.
c. Cuddalore, Nagappatinam, Nilgiri, Coimbatore, Theni, Thirunelveli, Kanyakumari.

 

Samacheer Kalvi 6th Science Water Intext Activities

Activity 1

Relative amount of water at various sources

Take a 20 litre bucket, a 500 ml mug, a 150 ml tumbler and a 1 ml spoon. If the capacity of the bucket is 20 litre, then it represents the total amount of water present on the Earth.

Now, transfer a mug of water from the bucket and it is 500 ml and then it represents the total amount of fresh water present in the Earth. The water left in the bucket represents seas and oceans. This water is not fit for human use.

The water present in the mug represents the freshwater which is present in frozen form on snow-covered mountains, glaciers and polar ice caps. This water is also not readily available for human use. Next, transfer 150 ml of water to the tumbler, then it represents the total amount of ground water. Finally, take one-fourth spoonful of water while the capacity of the spoon is 1 ml, then it represents the total amount of surface water (i.e) water seen in all the rivers, lakes and ponds of the world. It can be taken as potable water.

When such a small amount of potable water is available, then we should be more cautious in handling water. Is it not?
Answer:
Activity to be done by the students themselves

Activity 2
Conduct the activity with common salt, sand, chalk powder, charcoal powder and copper sulphate.

Fill up the following table.

Substance	Dissolves in water	Does not dissolve in water
common salt
sand
chalk powder
charcoal powder
copper sulphate

From the above activity, we could observe that common salt and copper sulphate dissolve in water and contribute their properties like colour and other properties to water but sand, chalk powder and charcoal powder do not dissolve in water.
Answer:

Substance	Dissolves in water	Does not dissolve in water
common salt	✓
sand		✓
chalk powder		✓
charcoal powder		✓
copper sulphate	✓

 

Activity 3

Water contains dissolved salts

Take some tap water in a china dish and heat it. Continue heating till all the water gets dried up. Stop the heating and look at the china dish. What do you observe inside the china dish?

Deposits of some solid particles on the surface of china dish can be observed. The deposit is of salts that are dissloved in water. This shows that water has dissolved salts in it.

Note : Do not use distilled water or water from purifier or RO unit and the like for this activity.

Activity 4
Spread a piece of wet cloth in the sunlight. Observe after some time. Where has the water in the wet cloth gone?

The water evaporates into the atmosphere due to the heat of the sun.

 

Activity 5

Condensation of water vapour

Take a glass half filled with water. Wipe the outer surface of the glass with a clean piece of cloth. Add some ice into the water. Wait for one or two minutes. Observe the changes that take place on the outer surface of the glass.

From where do water drops appear on the outer side of the glass?

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

Activity 6

Estimation of water consumed by a family on a day

Answer:

 

Samacheer Kalvi 6th Science Water Additional Questions

I. Choose the appropriate answer:

Question 1.
_______ form of water is present in mountain and polar region.
(a) Solid
(b) Liquid
(c) Gaseous
(d) All these
Answer:
(a) Solid

Question 2.
The melting point of Ice is ……….
(a) 100°C
(b) 0°C
(c) 0.100°C
(d) 10°C
Answer:
(b) 0°C

Question 3.
_______ water contains 0.05% to 1% of salts.
(a) Brackish
(b) Fresh
(c) Sea
(d) Sewage
Answer:
(b) Fresh

Question 4.
The human body requires ………. litres of water per day for proper functioning.
(a) 2 – 3 litres
(b) 3 – 4 litres
(c) 4 – 5 litres
(d) 1 – 2 litres
Answer:
(b) 3 – 4 litres

Question 5.
In plants, the loss of water in the form of vapour from the aerial parts through _______
(a) Root
(b) Shoot
(c) Stomatal Pores
(d) Fruit
Ans:
(c) Stomatal Pores

Question 6.
_______ water is obtained through open wells, tube wells or hand pumps, springs.
(a) Surface
(b) Frozen
(c) Saline
(d) Ground
Ans:
(d) Ground

Question 7.
_______ of Asia’s largest rivers flow from the Himalayas.
(a) 10
(b) 9
(c) 11
(d) 15
Answer:
(a) 10

Question 8.
Volume of liquid is measured by _______
(a) Gallon
(b) Litre
(c) Cusec
(d) Estuaries
Answer:
(c) Mangrove

Question 9.
_______ forests are found in pichavaram near Chidambaram
(a) Green
(b) Grass lands
(c) Mangrove
(d) Estuaries
Answer:
(c) Mangrove

 

II. Fill up the blanks:

1. _______ plays a vital role in the evolution and survival of life.
2. _______ is present in the air around us.
3. In the distribution of total 0.3% of surface water, _______ have 87% surface water.
4. The molecular formula of water is _______
5. The oceanic volcanoes which are present inside also add _______ to the sea.
6. Every year _______ is observed as the world water day.
7. The water vapour gets cooled and changes into tiny water droplets that form _______ in the sky.
8. A larger portion of water is _______ % of the total available fresh water in frozen state.
9. Water level in the reservoirs is measured in _______
10. Adoption of _______ and irrigation in agriculture.

Answers:

1. Water
2. Vapour
3. Lakes
4. H₂O
5. Salt
6. March 22nd
7. Clouds
8. 68.7
9. Cubic feet per second (cusecs)
10. Drip, Sprinkler

 

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

Question 1.
Mountains helps to regulate the temperature of our earth.
Answer:
False. Water helps to regulate the temperature of our earth.

Question 2.
Solid form of water is present in underground.
Answer:
False. Liquid form of water is present in underground.

Question 3.
Water while passing through layers of soil dissolves salt and minerals to a maximum extent.
Answer:
True.

Question 4.
Water freeze at 100° Celsius at normal pressure.
Answer:
False. Water freeze at 0° celsius at normal pressure.

Question 5.
When the air around the clouds is cool, these drops of water fall in the form of snow or rain.
Answer:
True.

Question 6.
Direct collection and use of rain water is called rain water harvesting.
Answer:
True.

Question 7.
Estuaries are harmful to unique plants and animal species.
Answer:
False. Estuaries are home to unique plants and animal species.

 

IV. Analogy:

Question 1.
Ice berg : Solid form :: Water vapour : _______
Answer:
Gaseous form.

Question 2.
Contain more than 3% of salt: _______ :: upto 3% of salt dissolved : Brackish water.
Answer:
Sea water.

Question 3.
Water bodies meet the sea : Estuaries :: Wet lands : _______
Answer:
Swamps.

Question 4.
Napier Bridge area : _______ :: Pallikkaranai: Wet land.
Answer:
Estuaries.

 

V. Give Short Answer:

Question 1.
Give the uses of water.
Answer:
Cooking food, washing cloths, cleaning utensils, bathing, agricultural etc.

Question 2.
What are the three forms of water?
Answer:
Water is available in solid, liquid and vapour forms.

Question 3.
Which places have fresh water?
Answer:
Ponds, pools, rivers, tube wells have fresh water.

Question 4.
How is 3% of fresh water distributed?
Answer:
Polar ice caps and glaciers – 68.7%
Groundwater – 30.1%
Another source of water – 0.9%
Surface water – 0.3%

Question 5.
Define – Saline water.
Answer:
Water with a large amount of dissolved solids is not potable or suitable for drinking. Such water is called saline water.

Question 6.
How water is classified based on its salinity?
Answer:
Based on salinity, water is classified into three main categories. Such as Fresh water, Brackish water and Sea water.

Question 7.
What are the salts dissolved in sea water?
Answer:
The salts are dissolved in sea water are sodium chloride, magnesium chloride and calcium chloride.

Question 8.
Define – Water cycle.
Answer:
The water on the earth evaporates into the atmosphere due to the heat of the sun. The water vapour in the atmosphere forms clouds. From the clouds, water falls on the earth in the form of rain or snow. By this natural process, water gets renewed. This is called water cycle.

Question 9.
What is Condensation?
Answer:
Water vapour which enters into the atmosphere by evaporation moves upward with air, gets cooled and changes into tiny water droplets that form clouds in the sky. This process is known as condensation.

Question 10.
What is transpiration?
Answer:
It is the process of loss of water from the aerial parts of a plant in vapour form. This is called transpriation.

Question 11.
What is frozen water?
Answer:
Water that is present in the frozen form as polar ice caps and glaciers are called frozen water. A large portion of water is 68.7% of the total available fresh water is in frozen state.

Question 12.
Define – Scarcity of water.
Answer:
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.

Question 13.
List the wet lands in Tamilnadu.
Answer:

1. Pichavaram Mangroves near Chidambaram.
2. Muthupet Mangrove wet-land.
3. Pallikkaranai wet-land in Chennai.
4. Chembarambakkam in Kancheepuram are a few examples of swamps in Tamilnadu.

Question 14.
What is meant by conservation of water?
Answer:
Saving water for the future generations by using water carefully and in a limited way is conservation of water.

 

VI. Answer in detail:

Question 1.
Draw and describe the total water on earth by pie chart.
Answer:
If the total water on earth be 100%, let’s see what percent would be the availability of fresh water. Look at the pie chart given below
From the pie chart, it can also be noted that 97% water is saline water. Only 3% found is the freshwater and that too in polar ice caps and glaciers. So this portion of water is not readily available for drinking.

The distribution of the totally available (3%) freshwater is as follows:
Polar ice caps and glaciers – 68.7%
Ground water – 30.1 %
Other source of water – 0.9%
Surface water – 0.3%
The distribution of total 0.3% of surface water is as follows:
Lakes – 87%
Rivers – 2%
Swamps – 11%
Thus the above pie chart explains that we have a very small amount of fresh water available for human usuage and so maintaining the water table and the conservation of water is very essential.

Question 2.
What are the methods of water conservation? Explain?
Answer:
1. Water management :

• Bringing awareness to the people.
• Recycling water by separating pollutants.
• Minimize the use of fertilizers.
• Controlling deforestation.
• Adopt drip and sprinkler irrigation in agriculture.

2. Rainwater harvesting:

• Collecting water from where it falls:
• Collecting water from the roof tops.
• Collecting flowing rain water :
• Collecting rain water by constructing dams.

Question 3.
Give the importance of water.
Answer:
The importance of water:

1. Our body uses water in all its cells, organs and tissues to help regulate its temperature and maintain other bodily functions.
2. On an average, the human body requires 2-3 litres of water per day for proper functioning.
3. Water helps in digestion of food and removal of toxins from the body.
4. Water is used in the domestic activities like cooking, bathing, washing clothes, washing utensils, keeping houses and common places clean, watering plants, etc.
5. It is also essential for the healthy growth of farm crops and farm stock and is used in the manufacture of many products.
6. Industry depends on water at all levels of production.

Question 4.
Describe water distribution and treatment system through flow chart.
Answer:

Question 5.
What are the reasons for scarcity of water?
Answer:
The main reasons for scarcity of water are:

1. Population explosion.
2. Uneven distribution of rainfall.
3. Decline of ground watertable.
4. Pollution of water.
5. Careless use of water.

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