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NCERT Solutions for class 4 E.V.S chapter 13 – A Rivers Tale
Back Exercise
Page No 107:
Question 1:
What is the colour of the river where it begins?
Answer
The river is blue at the place where it begins.
Page No 107:
Question 2:
At some places, there are many fish in the river, at others there are only a few and at some places there are dead fish. What could be the reason for this? Discuss.
Answer
It can be seen that at the beginning of the river, its water is clean. But, as it reaches the village, people start polluting it by throwing garbage into it and bathing their animals in it. As the river reaches the city, the poisonous wastes of industries and the sewage are thrown into it. All these things make the water unfit for the fish and as a result, so many of them die.
Page No 107:
Question 3:
What can be seen in the river before it reaches the village?
Answer
Before the river reaches the village, its water is clean and fresh. There are many fish in it and many other animals and birds come to it.
Page No 107:
Question 4:
At which places did the colour of the water in the river change? Why did this happen? Discuss.
Answer
The colour of the water in the river changes when it reaches the city. This is because the industrial waste, the sewage and the garbage from the city are thrown into it, thereby polluting it.
Page No 107:
Question 5:
Which of the places shown in the picture would you like to live in? Why?
Answer
I would like to live where the river started as the water there is clean and fresh there. Also, the environment there is very clean due to the presence of many trees.
Page No 107:
Question 6:
Would you like to change any of the things that you see in the picture? Why and how?
Answer
In the picture, I would like to bring the following changes: In the villages, people should not bathe animals in the river water. In the cities, the sewage and the industrial waste should not be thrown directly into the river. The industrial waste should first be treated to remove the harmful chemicals from it. The treatment of the sewage should also be done before releasing the waste water into the river. All these will make the river water free from harmful chemicals and the lives of the animals living in the water will not be disturbed.
Page No 108:
Question 1:
If you wanted to drink some water, from which part of the river would you like to drink? Why?
Answer
I would like to drink water from the beginning part of the river before it reaches the village. This is because the water of the river at this place is pure, clean and safe for drinking. As the river reaches the village, the water starts getting polluted and as it reaches the cities, its water becomes poisonous due to the dumping of industrial wastes in it.
Page No 108:
Question 2:
In the last part of the picture the river flows into the sea. Have you ever seen the sea? Where? In a movie, or somewhere else?
Answer
Disclaimer: The answer may vary according to the students’ observations and experiences. It is highly recommended that the students prepare the answer on their own.
Page No 108:
Question 3:
Have you ever been near a river or sea? When?
Answer
Disclaimer: The answer may vary according to the students’ observations and experiences. It is highly recommended that the students prepare the answer on their own.
Page No 108:
Question 4:
Show with your hands, how the waves in the sea move.
Answer
Disclaimer: The purpose of this section is to enhance the students’ creativity and imagination. It is highly recommended that the students perform this activity.
Page No 108:
Question 5:
Is the water from the sea drinkable? Why?
Answer
The water from the sea is not drinkable because it is very salty, which is not good for health.
Page No 108:
Question 6:
Do you think that there would be changes taking place in a river, pond or stream at different times of the year? What kind of changes would these be? Discuss.
Answer
In the summer season, the water level of the water bodies, such as river, pond or stream, decreases due to the evaporation of water. In the rainy season, the water level of the water bodies rises. The water of the ponds freezes in the winter in places where the climatic conditions are very cold.
Page No 109:
Question 1:
Will there be the same amount of water in the ponds or rivers during the rainy season and in summer?
Answer
The amount of water in water bodies such as river and ponds is not the same during the rainy season and the summer season. In summers, due to hot climate, the water gets evaporated easily, whereas in the rainy season, the amount of the water increases due to rain.
Page No 109:
Question 2:
Is there a pond, river or lake near your town or city ?
Find out–
• Are there any changes in the water during summers, the rainy season and in winters?
• What are the different kinds of fish found there?
• What kind of trees and plants grow around it?
• What are the kinds of birds that come there?
• Have you ever seen or read about floods? Where?
• What happens when there is a flood?
• Have you seen dirty water in a river or pond?
• How would you know if the water is dirty? If the water looks clean, can you be sure that it is alright to drink that water? Discuss.
Answer
Disclaimer: The purpose of this section is to encourage the students to observe their surroundings. The answer may vary according to the students’ observations and experiences. It is highly recommended that the students prepare the answer on their own.
Page No 112:
Question 1:
How is drinking water cleaned in your house?
Answer
By boiling, adding alum, etc.
Disclaimer: The purpose of this section is to encourage the students to observe their surroundings and be interactive. The answer may vary according to the students’ observations and experiences. It is highly recommended that the students prepare the answer on their own. The answer provided is just for reference.
Page No 112:
Question 2:
Find out the many different ways of cleaning water at home.
Answer
Different ways of cleaning water at home are as follows:
1. Boiling of water: This method kills the harmful germs present in the water. 2. Chemical treatment: Various chemicals such as chlorine can be added to the water depending on the type of impurity present in it. 3. Filtration: Impurities and germs present in the water can be filtered out by using water purifiers. There are several other ways of purifying water.
Page No 112:
Question 3:
Draw pictures showing any two ways of cleaning the water.
Answer
There can be several other ways of cleaning water.
Page No 107:
Question 1:
What is the colour of the river where it begins?
Answer
The river is blue at the place where it begins.
Page No 107:
Question 2:
At some places, there are many fish in the river, at others there are only a few and at some places there are dead fish. What could be the reason for this? Discuss.
Answer
It can be seen that at the beginning of the river, its water is clean. But, as it reaches the village, people start polluting it by throwing garbage into it and bathing their animals in it. As the river reaches the city, the poisonous wastes of industries and the sewage are thrown into it. All these things make the water unfit for the fish and as a result, so many of them die.
Page No 107:
Question 3:
What can be seen in the river before it reaches the village?
Answer
Before the river reaches the village, its water is clean and fresh. There are many fish in it and many other animals and birds come to it.
Page No 107:
Question 4:
At which places did the colour of the water in the river change? Why did this happen? Discuss.
Answer
The colour of the water in the river changes when it reaches the city. This is because the industrial waste, the sewage and the garbage from the city are thrown into it, thereby polluting it.
Page No 107:
Question 5:
Which of the places shown in the picture would you like to live in? Why?
Answer
I would like to live where the river started as the water there is clean and fresh there. Also, the environment there is very clean due to the presence of many trees.
Page No 107:
Question 6:
Would you like to change any of the things that you see in the picture? Why and how?
Answer
In the picture, I would like to bring the following changes: In the villages, people should not bathe animals in the river water. In the cities, the sewage and the industrial waste should not be thrown directly into the river. The industrial waste should first be treated to remove the harmful chemicals from it. The treatment of the sewage should also be done before releasing the waste water into the river. All these will make the river water free from harmful chemicals and the lives of the animals living in the water will not be disturbed.
Page No 108:
Question 1:
If you wanted to drink some water, from which part of the river would you like to drink? Why?
Answer
I would like to drink water from the beginning part of the river before it reaches the village. This is because the water of the river at this place is pure, clean and safe for drinking. As the river reaches the village, the water starts getting polluted and as it reaches the cities, its water becomes poisonous due to the dumping of industrial wastes in it.
Page No 108:
Question 2:
In the last part of the picture the river flows into the sea. Have you ever seen the sea? Where? In a movie, or somewhere else?
Answer
Disclaimer: The answer may vary according to the students’ observations and experiences. It is highly recommended that the students prepare the answer on their own.
Page No 108:
Question 3:
Have you ever been near a river or sea? When?
Answer
Disclaimer: The answer may vary according to the students’ observations and experiences. It is highly recommended that the students prepare the answer on their own.
Page No 108:
Question 4:
Show with your hands, how the waves in the sea move.
Answer
Disclaimer: The purpose of this section is to enhance the students’ creativity and imagination. It is highly recommended that the students perform this activity.
Page No 108:
Question 5:
Is the water from the sea drinkable? Why?
Answer
The water from the sea is not drinkable because it is very salty, which is not good for health.
Page No 108:
Question 6:
Do you think that there would be changes taking place in a river, pond or stream at different times of the year? What kind of changes would these be? Discuss.
Answer
In the summer season, the water level of the water bodies, such as river, pond or stream, decreases due to the evaporation of water. In the rainy season, the water level of the water bodies rises. The water of the ponds freezes in the winter in places where the climatic conditions are very cold.
Page No 109:
Question 1:
Will there be the same amount of water in the ponds or rivers during the rainy season and in summer?
Answer
The amount of water in water bodies such as river and ponds is not the same during the rainy season and the summer season. In summers, due to hot climate, the water gets evaporated easily, whereas in the rainy season, the amount of the water increases due to rain.
Page No 109:
Question 2:
Is there a pond, river or lake near your town or city ?
Find out–
• Are there any changes in the water during summers, the rainy season and in winters?
• What are the different kinds of fish found there?
• What kind of trees and plants grow around it?
• What are the kinds of birds that come there?
• Have you ever seen or read about floods? Where?
• What happens when there is a flood?
• Have you seen dirty water in a river or pond?
• How would you know if the water is dirty? If the water looks clean, can you be sure that it is alright to drink that water? Discuss.
Answer
Disclaimer: The purpose of this section is to encourage the students to observe their surroundings. The answer may vary according to the students’ observations and experiences. It is highly recommended that the students prepare the answer on their own.
Page No 112:
Question 1:
How is drinking water cleaned in your house?
Answer
By boiling, adding alum, etc.
Disclaimer: The purpose of this section is to encourage the students to observe their surroundings and be interactive. The answer may vary according to the students’ observations and experiences. It is highly recommended that the students prepare the answer on their own. The answer provided is just for reference.
Page No 112:
Question 2:
Find out the many different ways of cleaning water at home.
Answer
Different ways of cleaning water at home are as follows:
1. Boiling of water: This method kills the harmful germs present in the water. 2. Chemical treatment: Various chemicals such as chlorine can be added to the water depending on the type of impurity present in it. 3. Filtration: Impurities and germs present in the water can be filtered out by using water purifiers. There are several other ways of purifying water.
Page No 112:
Question 3:
Draw pictures showing any two ways of cleaning the water.
Answer
There can be several other ways of cleaning water.