Category: Class 7

Get Updated MP Board Solutions for Class 7 Special English Revision Exercises 2 Questions and Answers in PDF Format and download them free of cost. These are provided as per the latest exam pattern and syllabus. Access the topics of Chapter wise and communication skills, grammer part through the direct links available depending on the need. You can Download MP Board Class 7 English Solutions and can score highest grade in examination. Clear all your queries on the Mp Board Solutions for Class 7 English Chapter 21 Tansen Questions and Answers Subject by using the Madhya Pradesh State Board Solutions for existing.

MP Board Class 7th Special English Solutions Revision Exercises 2

If you are eager to know about the Madhya Pradesh State Board Solutions for Class 7 English you will find all of them here. You can identify the knowledge gap using these MP Board Solutions for English PDF and plan accordingly. Don’t worry about the accuracy as they are given after extensive research by people having subject knowledge along side from the latest English Syllabus.

Comprehension

Question 1.
Where does the poet breathe a song?
Answer:
The poet breathe’s a song into the air.

Question 2.
Why is Shravan Kumar famous?
Answer:
Shravan kumar is famous for his devotion and obedience to his blind parents.

Question 3.
What is a talking machine? What is a ‘talkie’?
Answer:
A talking machine is one that can talk. The modem gramophone is simply an improvement on this talking machine. A ‘talkie’ is a talking picture. This is the modern cinema.

Question 4.
Why did the Americans turn off their electric lights for a while when Edison died?
Answer:
Edison had invented the electric light. Therefore, when Edison died, the Americans turned off their electric lights for a while as a mark of respect to the wonderful inventor.

Question 5.
What kind of life did Sri Ramakrishna live as a temple priest?
Answer:
As a temple priest Sri Ramakrishna spent all his time in the service of ‘Kali’ the Divine Mother whom he worshipped out of religious duty. He lived a happy and a deeply religious life. He spent days and nights in prayer. He led a very hard life. He often went without food and water and ruined his health.

Question 6.
Why is quarrelling in the name of religion foolish?
Answer:
All the religions lead to the same goal. They also teach the same truth. In fact, people worship the same God under different names. Therefore, quarrelling in the name of religion is foolish.

Question 7.
What do you understand by the lines “till …….began No, time to wait?
Answer:
The smile appears in the eyes before it reaches the mouth. It takes a few moments. But the poet has no time even to view that smile.

Question 8.
What words and phrases did Anand fail to understand?
Answer:
The words and phrases which Anand failed to understand are = Cross, boiling of blood, get, novel.

Question 9.
Whom do the villagers give credit for their prosperity?
Answer:
The villagers give credit to God (who sends rain)

Question 10.
What is the best of all for the country people?
Answer:
The country faith is the best of all for the country-people.

Word Power

A. Choose the correct words to complete the sentences.

1. She is very ………. to me. (deer/dear)
2. He has a very bad eye ………… (sight/site)
3. The ………… was bright that day. (Son/sun)
4. He went inside the temple to ………… to god. (prey/pray)
5. He saved the ………. from the hunter. (dear/deer).

Answer:

1. dear
2. sight
3. sun
4. pray
5. deer.

B. Match the words in column (A) with the meaning given in column (B)

Answer:
1. → (b)
2. → (d)
3. → (a)
4. → (e)
5. → (c)

Grammar in Use

A. Rearrange the words in the following sentences and rewrite them to make meaningful sentences:

1. the/bet/is/What/?/
2. surprised/very/am/I/./
3. committed/a/blunder/he/./
4. archer/great/a/was/Dashrath/./
5. jobs/lost/Edison/many/./

Answer:

1. What is the bet?
2. I am very surprised.
3. He committed a blunder.
4. Dashrath was a great archer.
5. Edison lost many jobs.

B. Use the prefix ‘dis’ in the words given below and fill in the blank space, trust obey honest similar like

1. We should never ………. our elders.
2. People of ……….. nature never come together.
3. I ………. eating kachori.
4. Mr. Natawarlal is a ………… man.
5. Don’t ………… a priest.

Answer:

1. disobey
2. dissimilar
3. dislike
4. dishonest
5. distrust

Let’s Write

1. Write five sentences about the wood.
2. Write ten sentences on Shravan Kumar. Take the help of the clues, obedient, devoted, dutiful, pilgrimage, forest, put aside, thirsty, old and blind, river.
3. Write a paragraph on gramophone.
4. You are a cricket player of your school team. Give a set of three or four rules of the game using ought to and ought not to.
5. Write a message to your friend stating that as you didn’t attend the school that day and you want him to send the homework for English given by the teacher.
Answer:
1. The wood :
The wood is a place of beasts. We find many trees in the wood. The trees provide us fuel, food and fruit. Rishis live in the wood. They practise penance there.

2. Shravan Kumar was a devoted and obedient son. He used to carry his old and blind parents for pilgrimage. One day he was passing through the forest around Ayodhya. His parents asked him to bring water. Shravan took a pot. He went to Saryu river to bring water. His pot produced a gurgling sound. King Dashrath drought him to be a big animal. He shot an arrow. It pierced shravan’s chest. Shravan asked Dashrath to give water to his parents just then he died.

3. Edison invented the first talking machine. It looked very funny. However, it could talk. It was a new machine. The modern gramophone or record player is an improvement on the talking machine. The present day telephones and wireless sets are also talking machines. We can play the records on the gramophone of our choice and hear songs. The modem cinema is called a talkie due to the same.

4.Three or four rules of the game-

1. The bowler ought not to cross the crease- line while bowling.
2. The bowler ought not to throw the ball above chest height of the batsman.
3. We ought to obey the orders of the umpire.
4. We ought to play a fair game.

5. Class Room Activity in School

We believe the information shared regarding MP Board Solutions for Class 7 English Chapter 21 Tansen Questions and Answers as far as our knowledge is concerned is true and reliable. In case of any queries or suggestions do leave us your feedback and our team will guide you at soonest possibility. Bookmark our site to avail latest updates on several state board Solutions at your fingertips.

Get Updated MP Board Solutions for Class 7 Special English Revision Exercises 1 Questions and Answers in PDF Format and download them free of cost. These are provided as per the latest exam pattern and syllabus. Access the topics of Chapter wise and communication skills, grammer part through the direct links available depending on the need. You can Download MP Board Class 7 English Solutions and can score highest grade in examination. Clear all your queries on the Mp Board Solutions for Class 7 English Chapter 21 Tansen Questions and Answers Subject by using the Madhya Pradesh State Board Solutions for existing.

MP Board Class 7th Special English Solutions Revision Exercises 1

If you are eager to know about the Madhya Pradesh State Board Solutions for Class 7 English you will find all of them here. You can identify the knowledge gap using these MP Board Solutions for English PDF and plan accordingly. Don’t worry about the accuracy as they are given after extensive research by people having subject knowledge along side from the latest English Syllabus.

Comprehension

Question 1.
Write the central idea of the poem ’My Land’.
Answer:
The poet is all praise for his motherland. He would feel pride in serving and defending her.

Question 2.
How does a dictionary help us?
Answer:
A dictionary helps us in looking up the correct spellings of the words.

Question 3.
Where was the merchant going one day?
Answer:
He (the merchant) was going to a town one day.

Question 4.
What fell into the princess’ eye?
Answer:
The train of camels fell (right) into the princess’s eye.

Question 5.
How did the farmer make the\merchant pay him up?
A As.
Farmer framed the story cleverly to make the merchant pay him.

Question 6.
Whom did the lion appoint as his Courtiers and why?
Answer:
The lion appointed the crow, the fox and the leopard as his courtiers. He did so for the following reasons. The fox was wise and clever. The leopard was alert and swift-footed. The crow could fly high.

Question 7.
Why did the three advisers smile mysteriously?
Answer:
The lion and the three advisers were tired and hungry. They looked at the camel intently. Then they looked at each other. With their looks they planned to entrap the camel. Therefore, they smiled mysteriously.

Question 8.
What was the problem that the great emperor Akbar was not able to solve?
Answer:
Akbar drew a line on a piece of paper. The problem that the great emperor Akbar was not able to solve was how to make the line short.

Question 9.
What was the day fixed to fetch the horse?
Answer:
Any other day than the week days was fixed to fetch the horse.

Question 10.
What does the wasp ask the bee?
Answer:
The wasp asks the bee why the people love her better than him.

Word Power

A. Write the meaning and make sentences of the words given below:

Answer:

B. Give one word for the following:

1. A person who is kept in a prison…….
2. A person who advises………..
3. A person who buys and sells goods in large quantities……….
4. One who remains faithful …………
5. An area full of sand …………..

Answer:

1. Prisoner
2. Adviser
3. Whole seller
4. Loyal
5. Desert

Grammar in use

A. Fill in the blanks with suitable prepositions:

1. The members …………this family are.
2. Very fond ………… watching.
3. TV ………… night.
4. They love ………… watch all the serials.
5. Which are telecast ……….. various channels.

Answer:

1. of
2. of
3. at
4. to
5. on

B. Fill in the following blank spaces a, an, the as required:

1. English is not ………… easy language.
2. He is ………. cleverest boy in ………… class.
3. She is ……….. old woman of ninety.
4. The train was ………… hour late.
5. I saw ……………. cat, ……….. cow and ………… horse.

Answer:

1. an
2. the, the
3. an
4. an
5. a, a, a

Let’s Write

1. You are Reena Mishra. Your sister is getting married next month. Write an invitation to your friend asking her to come at least for a week before so that she can enjoy all the programmes of marriage.
2. Write one funny incident of your life.
3. Write a paragraph on My Mother Land.
4. Write a letter to your friend describing your visit to a hill station.
5. Write a paragraph on good manners.
Answer:
1. Invitation of friend on sister’s marriage.

F-4, Dr. R.P. Colony,
Gwalior.
Dated 8th June, 2006

My Dear Ram Lai,
You will be glad to know that my sister’s marriage ceremony comes off next month. The marriage party will come from Delhi. I am inviting you to my sister’s marriage. You must come at least a week before it. I have invited some other friends also. But I need you most, because of your experience. You can also enjoy all the programmes of marriage. All the things will be bought in your presence. Please do come. More when we meet.

Yours ever,
Reena Mishra

2. A Funny Incident of My Life :

Life is full of incidents. Some incidents are happy. Others are sad or even funny. One day I received a telegram. Its message was ‘your dear friend Hari has met with a serious accident’. Come soon to Dayal Nursing Home where he is breathing his last. I hired a three wheeler and started for Najafgarh. I was about to enter the Nursing Home when my friend called me. He asked me in which ward my father was admitted. I could understand nothing. He showed me a telegram. The message of his telegram was-your friend will come to visit his father in Nursing Home at 4 p.m. today, please reach there and meet him. Later, we realised that it was the 1st April day.

3. My Mother Land

Read the Summary of the poem ‘My Land’.

4. Letter to friend describing your visit to a hill station.

476-L Model Town,
Ludhiana.
17th July, 2006

Dear Madhuri
I have returned from Simla. Being sick of the heat of Delhi, I had gone to Simla in the first week of June. It is, you know the best hill-station. It has various picnic spots such as Jakhu, Prospects Hill, Glenn, Chedwich Falls etc.
We used to go to the Mall every night and enjoyed the scenic beauty of hills. Warm clothes and umbrellas were used every day there was greenery all around. It was very pleasant to be in bed with blankets in June. The Mall and the Ridge gave the impression of fashion parade. We visited the Hanuman Mandir on every Tuesday.
Rest when we meet with love.

Yours sincerely,
Manoj Kaushik

5. Good Manners :

Good manners are taught to us by our parents, teachers and elders. We show good manners by what we say and the way we say it. Good manners are also expressed by the way we behave and conduct ourselves. Being polite and considerate is good manners. Being rude and arrogant in our words and deeds shows bad manners. Similarly, being quarrelsome and argumentative is bad manners.

Speaking softly and gently is good manners. If a person shouts it is bad manners. Using abusive and offensive language is also bad manners. It is good manners to use appropriate language at all times. One who uses words like thank you, sorry, pardon and welcome in an appropriate way shows good manners.

People around us are friendly with us and appreciate us if we are good mannered. If we are good mannered we can live a life of peace, harmony and good cheer.

We believe the information shared regarding MP Board Solutions for Class 7 English Chapter 21 Tansen Questions and Answers as far as our knowledge is concerned is true and reliable. In case of any queries or suggestions do leave us your feedback and our team will guide you at soonest possibility. Bookmark our site to avail latest updates on several state board Solutions at your fingertips.

Get Updated MP Board Solutions for Class 7 Special English Solutions Chapter 18 The Great Pyramid Questions and Answers in PDF Format and download them free of cost. These are provided as per the latest exam pattern and syllabus. Access the topics of Chapter wise and communication skills, grammer part through the direct links available depending on the need. You can Download MP Board Class 7 English Solutions and can score highest grade in examination. Clear all your queries on the Mp Board Solutions for Class 7 English Chapter 18 The Great Pyramid Questions and Answers Subject by using the Madhya Pradesh State Board Solutions for existing.

MP Board Class 7th Special English Solutions Chapter 18 The Great Pyramid

If you are eager to know about the Madhya Pradesh State Board Solutions for Class 7 English you will find all of them here. You can identify the knowledge gap using these MP Board Solutions for English PDF and plan accordingly. Don’t worry about the accuracy as they are given after extensive research by people having subject knowledge along side from the latest English Syllabus.

The Great Pyramid Text Book Exercise

Read and Learn

Comprehension

A. Answer these questions

Question 1.
What was ancient Egypt famous for? What was its greatest glory?
Answer:
Ancient Egypt was famous for its art and civilization. Its greatest glory was its pyramids.

Question 2.
Who built the Great Pyramid?
Answer:
Cheops, the most famous of all Egyptian kings, built the Great Pyramid.

Question 3.
What according to the ancient Egyptians, would happen to their kings after their death?
Answer:
According to the ancient Egyptians their dead kings would come back to life after a long time of thousands of years.

Question 4.
Why did the ancient Egyptians take great care to preserve the bodies of their dead kings?
Answer:
The ancient Egyptians believed that the safety of the common people lay in the safety of their kings. Therefore, they took great care to preserve the bodies of their dead kings.

Question 5.
Why did they build huge pyramids for the tombs?
Answer:
They wanted the king’s body to be safe till* he came back to life. The time could not destroy huge pyramids. So they built huge pyramids for the tombs.

Question 6.
How many slaves were employed in building the Great Pyramids?
Answer:
A hundred thousand (one lakh) slaves were employed in building the Great Pyramid.

Question 7.
How long did it take to build?
Answer:
It took twenty years to build the Great Pyramid.

B. Choose the correct option.

Question 1.
Egypt is famous for ………….
(i) the pyramids
(ii) sports
(iii) buildings
Answer:
(i) the pyramids

Question 2.
Cheops was a very young …………
(i) slave
(ii) prince
(iii) girl
Answer:
(ii) prince

Question 3.
The (height of a Great Pyramids is ……….
(i) 400 ft.
(ii) 500 ft.
(iii) 600 ft.
Answer:
(ii) 500 ft.

Question 4.
In the Great Pyramid, the royal architect used ……………
(i) about two and half million blocks of stone.
(ii) about three and a half million blocks of sand.
(iii) about three and a half million blocks of logs.
Answer:
(i) about two and half million blocks of stone.

Question 5.
The Great Pyramid is
(i) hollow
(ii) solid
(iii) weak.
Answer:
(ii) solid

Word Power

A. Fill in the blanks with the words given below:

(tomb, glory, preserved, buried, skilled, slaves, everlasting, art, architect)
The Taj Mahal is the greatest ………. of the Moghuls. It is a ………… built by Shah Jahan in the memory of his wife, Mumtaz Mahal. She was …………. in it, but her body was not ………… like those of the Egyptian kings. The ………… who built Taj was Ustad Isa. Thousands of workers from all over the country and perhaps many more …………. worked on it for about seventeen years. The Taj is a work of ………… and it will remain an …………. wonder of the world.
Answer:
glory, tomb, buried, preserved, architect, slaves, art, everlasting.

B. Find the opposites of the words listed below from the words given in the box and write them:

Answer:

1. ancient – modern
2. huge – tiny
3. civilized – uncivilized
4. wise – fool
5. difficult – easy
6. impossible – possible
7. death – life
8. royal – common
9. kind – unkind

Grammar in Use

A. Study the sentences in the table given below:

Now write ten meaningful sentences from the table given below.

Answer:

1. Gopal cannot do it unless I help him.
2. Sajid will not complete the work unless I help him.
3. Sajid may not be able to complete the work unless I help him.
4. He cannot do it unless I help him.
5. He will not do it unless he is paid for it.
6. He will not complete the work unless you give him all the materials.
7. He may not be able to complete the work unless you give him all the materials.
8. The architect cannot complete the work unless you give him all the materials.
9. The architect may not be able to complete the work unless he is given a month’s time.
10. The architect will not complete the work unless he is paid for it.

B. Change the sentences below, using since? it the beginning instead of ‘so’ in the middle.
Example:
He had no money, so he did not enter the, shop.
Since he had no money, he did not enter the shop

1. It was a public holiday, so there was no school that day.
2. You like these songs very much, so Sita will sing them for you
3. You work hard, so you will pass the examination.
4. There is no air on the moon, so there cannot be any life on it.
5. I have no money, so I can’t buy this car.

Answer:

1. Since it was a public holiday, there was no school that day.
2. Since you like these songs very much, Sita will sing them for you.
3. Since you work hard, you will pass the examination.
4. Since there is no air in the moon, there cannot be any life on it.
5. Since I have no money, I can’t buy this car.

Let’s Talk (work in pairs)

A. Discuss in pair, where the following are situated and then match them. Write the correct answer:

Answer:
1. → (A)
2. → (d)
3. → (e)
4. → (c)
5. → (b)
6. → (g)
7. → (f)

B. Discuss with your teacher about the stupas of Sanchi.

Find answers to the following questions:
(a) Where is Sanchi?
(b) Who built these Stupas? Why?
(c) What are they famous for?
Answer:
(a) Sanchi is in Madhya Pradesh.
(b) The kings of that period built there stupas. They wanted to place the rechies in them.
(c) They are famous because relies of Buddha or Buddhist monks are placed in them.

Let’s Write

A. Write about the stupas of Sanchi using the following words:
ancient, architect, imagine, huge, blocks, solid, figures, model
Answer:
Stupas of Sanchi

B. Write a short account of the Great Pyramid.
Hints : Who built it and why?
Time taken to build it
Number of slaves employed
Its base, height and its faces A wonder of the world.
Answer:
The great Pyramid was built by Cheops, the most famous King of Egypt about four thousand years ago. It took twenty years to build this Great Pyramid. One hundred thousand slaves were engaged to build it. It stands on a base of more than twelve acres of land. Its height is 500 feet. Its faces are very smooth. About two and a half million blocks of stone were used for it. Each block weighed about two and a half tons. It is very solidly built. There is no room even for a single hair to be slipped in between any two blocks of stones. This everlasting pyramid is the glory of Egypt and remains a wonder of the world to this day.

Let’s Do it

A. Collect more information and pictures of the Kutub Minar, Red Fort and the Golden Temple. Make a chart and write at least two or three sentences about each of them.
Answer:
Class-room Activity.

The Great Pyramid Word Meaning 

We believe the information shared regarding MP Board Solutions for Class 7 English Chapter 18 The Great Pyramid Questions and Answers as far as our knowledge is concerned is true and reliable. In case of any queries or suggestions do leave us your feedback and our team will guide you at soonest possibility. Bookmark our site to avail latest updates on several state board Solutions at your fingertips.

Get Updated MP Board Solutions for Class 7 Special English Solutions Chapter 11 Leisure Questions and Answers in PDF Format and download them free of cost. These are provided as per the latest exam pattern and syllabus. Access the topics of Chapter wise and communication skills, grammer part through the direct links available depending on the need. You can Download MP Board Class 7 English Solutions and can score highest grade in examination. Clear all your queries on the Mp Board Solutions for Class 7 English Chapter 11 Leisure Questions and Answers Subject by using the Madhya Pradesh State Board Solutions for existing.

MP Board Class 7th Special English Solutions Chapter 11 Leisure

If you are eager to know about the Madhya Pradesh State Board Solutions for Class 7 English you will find all of them here. You can identify the knowledge gap using these MP Board Solutions for English PDF and plan accordingly. Don’t worry about the accuracy as they are given after extensive research by people having subject knowledge along side from the latest English Syllabus.

Leisure Text Book Exercise

Listen and Repeat

Comprehension

Answer the questions given below:
Question 1.
Why does the poet say that it is a poor life?
Answer:
The poet’s life is full of care. He has no time to watch the beauties around him. Therefore, he says that it is a poor life.

Question 2.
What do the busy and anxious people miss daily in their lives?
Answer:
The busy and anxious people miss,the general happenings around them, daily in their lives.

Question 3.
Do the people have time to see the beauty of nature?
Answer:
No, the people do not have time to see the beauty of nature.

Question 4.
How does the poet present scenic beauty of nature?
Answer:
The poet presents the scenic beauty of nature as enchanting. The groves, woods and streams are full of eye-catching beauty.

Question 5.
What do you understand by the lines, ’No time to wait till ………. began.’?
Answer:
The smile appears in the eyes before it reaches the mouth. It takes a few moments. But the poet has no time even to view that smile.

Question 6.
What is the theme of the poem?
Answer:
The theme of this poem is that a careworn life is a miserable life.

Word Power

Use the words given below and complete the sentences:
(full of, no time, beneath, woods, hide, as long as)
Example :
We can not go outside as long as it rains.

1. People stand ………….. it rains.
2. The rabbits run around in the ……………
3. The river is …………
4. The man has …………. watch.
5. The birds …………. nests.
6. you do not hurt animals they ………… do not harm you.

Answer:

1. beneath
2. woods
3. full of
4. no time
5. hide
6. As long as

Let’s Talk

Visit a river side/lake nearby and talk about it. Find answers to the following.
Question 1.
Did you see any birds, fish etc. near the lake?
Answer:
I saw many birds, fish etc. hear the lake.

Question 2.
What frees grow near the water body? Find the names if possible.
Answer:
Many trees grow near the water body (river/lake). They are neem, peepal, mango etc.

Question 3.
What was most interesting in the visit?
Answer:
The sight of the visitors and their boating was most interesting in the visit.

Question 4.
Do lot of tourists come there? Why?
Answer:
Yes, lot of tourists come there. They come there to learn about the eating and clothing habits of the local residents. They also learn about their way of living, traditions and cultures.

Let’s Write

Question 1.
A. Write three sentences about the woods.
B. Write three sentences about the sky.
Answer:
A. The woods

1. The woods look pleasant only in pictures.
2. All sorts of trees are found in the woods.
3. Dangerous animals live in the woods.

B. The Sky

1. The sky is above the earth.
2. It is full of stars at night.
3. Clouds roar in the sky during rainy season.

Let’s Do It

Draw the picture of different images that appear in the poem and name them.
Answer:
Attempt yourself.

Leisure Word Meanings

We believe the information shared regarding MP Board Solutions for Class 7 English Chapter 11 Leisure Questions and Answers as far as our knowledge is concerned is true and reliable. In case of any queries or suggestions do leave us your feedback and our team will guide you at soonest possibility. Bookmark our site to avail latest updates on several state board Solutions at your fingertips.

MP Board Class 7th Science Solutions Chapter 9 Soil

Soil Intext Questions

Question 1.
I wonder why I found some pieces of plastic articles and polythene bags in the soil sample collected from the roadside and the garden?
Answer:
It is because people throw used plastic things and polythene bags in the soil.

Question 2.
I want to know whether ‘the soil from a field can be used to make toys?
Answer:
Yes.

Question 3.
I want to know: What kind of soil should be used for making making  and surahis?
Answer:
Clayey soil.

Question 4.
Boojho wondered why there was a difference in the absorption of water in the two squares?
Answer:
Because different soils are used to make the two squares.

Question 5.
What is the difference between rate of percolation and the amount of water retained?
Answer:
Rate of percolation is the amount of water percolated per unit time through soil. Whereas the amount of water retained is the amount of water absorbed by soil. Thus, rate of percolation and water retention are opposite attributes.

Activities

Activity 1
Collect some soil samples and observe them carefully. You can use a hand lens. Examine each sample carefully and fill in Table. Answer:
Table

Activity 2
Take a little soil. Break the clumps with your hand to powder it. Now take a glass tumbler, three quarters filled with water, and then add a handful of soil to it. Stir it well with a stick to dissolve the soil. Now let it stand undisturbed for some time. Afterwards, observe it and answer the following questions:

1. Do you see layers of particles of different sizes in the glass tumbler?
2. Draw a diagram showing these layers?
3. Are there some dead rotting leaves or animal remains floating on water?

Answer:

1. Yes
2. 
3. Yes

Activity 3
Find from your teachers, parents and farmers the type of soils and crops grown in your area. Enter the data in the following Table,

1. Which kind of soil would be most suitable for planting rice?
2. Soil with a higher or lower rate of percolation?

Answer:

1. Loamy soil.
2. Lower rate of percolation.

Soil Text Book Exercises

Tick the most suitable answer in questions 1 and 2.

Question 1.
In addition to the rock particles, the soil contains?

1. Air and water
2. Water and plants
3. Minerals, organic matter, air and water
4. Water, air and plants.

Answer:
3. Minerals, organic matter, air and water.

Question 2.
The water holding capacity is the highest in?

1. Sandy soil
2. Clayey soil
3. Loamy soil
4. Mixute of sand and loam.

Answer:
2. Clayey soil.

Question 3.
Match the items in Column I with Column II:

Answer:

(i) (b)
(ii) (c)
(iii) (a)
(iv) (e)
(v) (d).

Question 4.
Explain how soil is formed?
Answer:
The soil is the mtter which cover the top most layer of the earth in most of area. It is one of the most important natural resources. Long ago earth was a very hot sphere and then converted into a very hard and rocky land. These rocks were broken into smaller pieces by violent earthquakes. Volcanic eruptions also made the rocks and lava into smaller pieces. In cold temperatures the ice in the services of rocks expanded to break it into smaller pieces and thus gradually the soil was formed. The nature of any soil depends upon the rocks from which it has been formed and the type of vegetation that grows in it.

Question 5.
How is clayey soil useful for crops?
Answer:
Clayey soil is good at retaining water. They, are rich in humus and are very fertile. They also hold sufficient water due to the presence of smaller particles and certain enough air due to the presence of some large particles.

Question 6.
List the differences between clayey soil and sandy soil?
Clayey soil:

1. They contains more than 50% of clay particles.
2. Water holding capacity is very high.
3. Suitable for plant growth.
4. Low percolation rate.

Sandy Soil:

1. They contains about 60% of sand particles.
2. Water holding capacity is very low.
3. Not suitable for plant growth.
4. High percolation rate.

Question 7.
Sketch the cross section of soil and label the various layers?
Answer:

Question 8.
Razia conducted an experiment in the field related to the rate of percolation. She observed that it took 40 min for 200 mL of water to percolate through the soil sample. Calculate the rate of percolation.
Answer:
We know that,

Thus, the rate of percolation is 5ml/min.

Question 9.
Explain how soil pollution and soil erosion could be prevented?
Answer:
Polythene bags and plastics pollute the soil. They also kill the organisms living in the soil. That is why there is a demand to ban the polythene bags and plastics. Other substances which pollute the soil are a number of waste product, chemicals and pesticides. Waste products and chemicals should be treated before they are released into the soil.

The use of pesticides should be minimised. Soil erosion can be slowed down and soil can be conserved by regulating the factors responsible for it. Some methods to prevent or slow down the soil erosion are:

1. To stop the unnecessary cutting of forests and trees.
2. To stop the excessive use of grass land due to overgrazing by cattle.
3. Growing vegetation along the boundary of the fields and open grounds.
4. Making use of proper and scientific methods for cultivation such as crops rotation. This maintains the natural fertility of the soil and at the same time soil also maintains its capacity to hold water. Soil remains wet and cannot be easily carried away by water and blown up by wind.
5. Making use of scientific methods for irrigation and water drainage.
6. Gutting the hill slopes into steps or terraces and adopting terrace cultivation on hill slopes.

Question 10.
Solve the following crossword puzzle with the clues given:

Across:

2. Plantation prevents it.
5. Use should be banned to avoid soil pollution.
6. Type of soil used for making pottery.
7. Living organism in the soil.

Down:

1. In desert soil erosion occurs through.
3. Clay and loam are suitable for cereals like.
4. This type of soil can hold very little water.
5. Collective name for layers of soil.

Answer:

Soil Additional Important Questions

Soil Objective Type Questions

Question 1.
Choose the correct alternative:

Question (i)
The constituents of the soil are –
(a) Mineral particles, air and water
(b) Living of organisms
(c) Organic and inorganic substances
(d) All of these.
Answer:
(d) All of these.

Question (ii)
Soil is the thin layer of fine material containing –
(a) Organic matter
(b) Air and water
(c) Weathered rock materials
(d) All of these.
Answer:
(d) All of these.

Question (iii)
Soil formation is brought about by –
(a) physical factors
(b) Chemical factors
(c) Biological agent
(d) All of these.
Answer:
(d) All of these.

Question (iv)
Which profile contains humus –
(a) A – horizon
(b) B – horizon
(c) C – horizon
(d) R – horizon.
Answer:
(a) A – horizon

Question (v)
Which of these has the smallest size of particles –
(a) Sand
(b) Silt
(c) Clay
(d) Gravel.
Answer:
(b) Silt

Question (vi)
What kind of soil is best for growing cotton –
(a) Black soil
(b) Alluvial soil
(c) Red laterite soil
(d) Mountain soil.
Answer:
(a) Black soil

Question (vii)
What kind of soil is good for growing tea and coffee –
(a) Red laterite soil
(b) Black soil
(c) Laterite soil
(d) Mountain soil.
Answer:
(c) Laterite soil

Question (viii)
The dead and decaying organisms are –
(a) Humus
(b) Gravel
(c) Clay
(d) Inorganic material.
Answer:
(a) Humus

Question (ix)
Which kind of soil is best for growing wheat, rice and sugarcane –
(a) Black soil
(b) Mountain soil
(c) Alluvial soil
(d) Desert soil
Answer:
(c) Alluvial soil

Question 2.
Fill in the blanks:

1. Wheat and rice grow best in …………… soil.
2. Humus is present in the ………….. layer of soil, known as the ………….. horizon.
3. Clay is the smallest size of particles less than …………… in diameter.
4.  …………… is a mixture of sand, silt, clay and humus.
5. Weathering of rocks is a …………… process.
6. …………… is the breaking down of rocks into smaller pieces.
7. Soil commonly found in India is of …………….. main types.
8. Red colour of the soil is due to ………………

Answer:

1. Alluvial
2. Upper, A
3. 0.002 mm
4. Loam
5. Slow
6. Weathering
7. Six
8. Iron.

Question 3.
Which of the following statements are true (T) or false (F):

1. The soil is uppermost layer of the land surface.
2. The soil with particle size greater than 2 mm in diameter is gravel.
3. The soil with particle size greater than 2 mm in diameter is clay.
4. Decayed organic matter in the soil forms humus.
5. Most fertile farm lands consist of alkaline soil.
6. No humus is present in C – horizon.
7. Black soil is rich in iron and magnesium.
8. B – horizon is the most fertile part of the soil.
9. Laterite soil is rich in nutrients.
10. Soil is classified in sand, silt and clay.
11. The process of .carrying away of top soil by natural process is called soil erosion.
12. Black soil is loamy in texture with plenty of humus.
13. Overgrasing is a means of soil conservation.
14. Extremely acidic soil supports plants.
15. Planting of trees in a large area is known as afforestation.

Answer:

1. True (T)
2. True (T)
3. False (F)
4. True (T)
5. False (F)
6. True (T)
7. True (T)
8. False (F)
9. True (T)
10. True (T)
11. True (T)
12. False (F)
13. False (F)
14. False (F)
15. True (T).

Match the items in Column A with items in Column B:

Answer:

(i) (d)
(ii) (c)
(iii) (a)
(iv) (b)
(v) (e).

Soil Very Short Answer Type Questions

Question 1.
Mention two main components of soil?
Answer:
The two main components of soil are mineral particles and organic particles.

Question 2.
Name the different types of particles present in the soil?
Answer:
The different types of particles present in the soil are water, air, humus, mineral particles and living organisms.

Question 3.
What is soil?
Answer:
The soil is the outer layer of earth’s crust capable of supporting plant growth.

Question 4.
Mention two functions of soil?
Answer:
The two functions of soil are:

1. It provides water and minerals to the plants.
2. It provides anchorage to the plants.

Question 5.
What is the role of plants in the formation of soil?
Answer:
The roots of plants on penetrating into the crevices of rocks break these and help in the formation of soil.

Question 6.
Name some of the living organisms which are present in the soil?
Answer:
Fungi, bacteria, earth worms, round worms, and protozoams are the living organisms present in the soil.

Question 7.
What do you mean by soil texture?
Answer:
The structure or texture of soil determines the relative proportion of particles of different sizes.

Question 8.
What is the difference between soil texture and structure?
Answer:
Soil texture pertains to particle size, composition of a soil and soil structure refers to arrangement of soil particles into aggregates.

Question 9.
What is meant by the term weathering?
Answer:
Weathering is the breaking down of huge pieces of rocks into smaller pieces by the action of natural forces, such as water, wind, glaciers and roots of plants.

Question 10.
Which layer of soil contains the largest rock pieces?
Answer:
Bedrock contains the. largest rock pieces.

Question 11.
Which layer of soil will have the highest humus content and which the least?
Answer:
The upper most layer (A-horizon) will have the highest humus content and lowest layer (C-horizon) will have the least.

Question 12.
Which types of soil is most suitable for crops like wheat, rice and sugarcane?
Answer:
Alluvial soils is the most suitable for crops like wheat, rice x – and sugarcane.

Question 13.
Define residual soil?
Answer:
The soil which remains at the place of its formation is called residual soil.

Question 14.
Which soil is classified as alluvial type?
Answer:
The soil transported by flowing water is classified as alluvial type.

Question 15.
What are mountainous soil?
Answer:
Mountainous soil consist of clay, shales, sandstones and limestones. This type of soil is usually found in depressions and valley basins or on gently inclined slopes.

Question 16.
Define loam?
Answer:
Loam is a mixture of sand, silt and clay and also has humus in it.

Question 17.
What is soil pollution?
Answer:
The contamination of soil with excess of fertilizers, herbicides, weedicides, insecticides and industrial waste is called soil pollution.

Question 18.
Define soil moisture?
Answer:
Soil holds water in it, which is called soil moisture.

Question 19.
Name the three types of soil erosion?
Answer:
The three types of soil erosion are sheet erosion, gaily erosion and wind erosion.

Question 20.
How does vegetation help to prevent soil erosion?
Answer:
Flowing water and wind take away the top layer of the soil if there is no vegetation. The grasses, trees hold the soil in place.

Question 21.
How does soil erosion take place?
Answer:
Soil erosion can take place by natural processes such as floods, forest fire, winds, deforestation and overgrazing.

Question 22.
Which horizon of soil profile contains humus?
Answer:
A – horizon of soil profile contains humus.

Question 23.
Which type of soil is classified as residual soil?
Answer:
The soil, which remains at the place of its formation is called residual soil. This type of soil is generally poor in nitrogen, phosphorus and humus.

Question 24.
The soil at a given place was found to consist of sand stones, clay, shales and limestone. What is the type of the soil and how it might have formed?
Answer:
The type of the soil is mountainous soil. It might have formed, when the weathered soil particles are taken away to other places.

Soil Short Answer Type Questions

Question 1.
What does soil consist of?
Answer:
Soil consists of tiny bits of mineral particles which come from larger rocks and humus which is dark brown in colour and consists of decaying remains of plants and animals. Soil also contains water, air and living organisms such as bacteria, fungi, earth worms, round worms, and insects etc.

Question 2.
How is the soil formed? Explain in brief?
Answer:
Millions years ago, the surface of earth was very hard, rugged and rocky. In the long run, weathering of these rocks resulted in formation of soil which with the flow of river water came down to the lower plains and got deposited. Gradually it spread out on whole surface of the earth. Formation of soil is a very slow process. In this process rocks crack and break down into fine particles to form soil.

Question 3.
Define alluvial soil and its distribution?
Answer:
Alluvial soil is loamy soil which contains abundant amount of water in it. This is very fertile soil. This type of soil is very suitable for the production of wheat and rice. This soil is found in the plains of northern India, i.e., in the state of Punjab, Bihar, Haryana, Uttar Pradesh and West Bengal.

Question 4.
What are physical properties of soil?
Answer:
The physical properties of soil are:

1. Colour
2. Moisture storage capacity
3. Texture
4. Presence of living organisms
5. Porosity.

Question 5.
Give an account of the importance of physical properties of soil?
Answer:
The physical properties .of soil exert a great influecne on soil fertility. These are taken into consideration when soil is to be used as a medium for plant growth but also when soils are to be [ used as a structural material for making highways, dams, foundation for buildings as well as for the manufacture of bricks and tiles.

Question 6.
What are organic and inorganic components of soil?
Answer:
The inorganic components of soil comprise minerals which are derived from fragmentation and weathering of rocks. The porespaces formed between the mineral particles of soil are filled with water and gases. The organic component of soil comprise organic wastes, dead animals, plants and their decomposition products.

Question 7.
Explain the role of various organisms present in the soil?
Answer:
Bacteria in the soil helps in decomposing dead remains of plants and animals to make humus. Some bacteria can convert atmospheric nitrogen into water soluble nitrates which plants can easily use for their growth. Earthworms help in loosening of soil. They also improve the texture of the soil thus causing better growth of plants.

Question 8.
Name four common sources of pollution of soil?
Answer:
The common sources of pollution of soil are:

1. Excessive use of fertilisers.
2. Spraying of crops with insecticides and herbicides.
3. Garbage and other kitchen refuge.
4. Industrial wastes such as chemicals, plastic, leather, fly ash, etc.

Question 9.
Define A – horizon layer. Give also the main characteristic of A – horizon.
Answer:
A – horizon layer:
The uppermost layer of the soil is called A – horizon. It is generally known as upper soil or earth’s crust. The main characteristics of this layer of soil are as under:

1. It generally bears dark colour.
2. It contains lot of dead and decaying plant and animal matter called humus.
3. Due to presence of humus this layer is highly fertile.
4. The soil in this layer is porous, soft and has comparatively more water retaining capacity.
5. In this layer living organisms such as earth worms, insects, bacteria and fungi etc. are found.

Question 10.
Define B – horizon layer. Also give the main characteristics of B – horizon.
Answer:
B – horizon layer:
This layer lies next to A – horizon. The main characteristics of this layer of soil are as under:

1. The colour of this layer is comparatively dull.
2. This layer of soil is usually harder and more compact than the top soil.
3. This layer contains very less amount of organic matter in it.
4. This layer is rich in iron oxide and soluble mineral salts,
5. Roots of large and old trees are found in this layer.

Question 11.
Differentiate between Alluvial soils and Desert soils.
Answer:
Alluvial soils:

1. Loamy in texture with plenty of humus.
2. Very fertile, good for crops like wheat and rice.
3. In India, it is mainly found in the plains of Uttar Pradesh, Haryana, Bihar, West Bengal and in the coastal regions of Orissa and Andhra Pradesh.

Desert soils:

1. Soil sandy and porous, cannot hold much water.
2. If irrigated, crops can be grown.
3. In India, it is mainly found in Rajasthan and in some parts of Gujarat.

Soil Long Answer Type Questions

Question 1.
Describe the various steps involved in the formation of soil?
Answer:
There is a hard surface of the rocks just below the layer of the soil. In the past, these rocks were broken into smaller pieces by a process known as weathering. Weathering is the breaking down of huge pieces of rocks into smaller pieces by the action of natural forces, such as water, wind, glaciers and roots of plants, etc.

1. Rain water enters crevices of rocks. In winter, as this water freezes, it expands. This expansion breaks the rocks into smaller pieces.

2. The broken pieces roll down by the force of flowing or wind.

3. The broken pieces get converted into very fine particles, and mix with humus to form soil.

4. Roots of tree growing through rocks exert great pressure on the rocks. This causes cracks in the rocks, leading to weathering.

5. Large variation in day and night temperatures.

6. In hot and humid climates, the minerals in rocks react with oxygen of the air. Such oxidised rocks crumble to form soil.

Question 2.
Describe various types of soil on the basis of their classification?
Answer:
There are mainly six types of soil found in India. These are:

1. Red soil:
It is red in colour due to the presence of red iron oxide in it. It is poor in humus but can be made fertile by adding manure. This type of soil is generally found in southern part of. India.

2. Black soil:
It is derived from the lava of volcanic eruptions and is rich in minerals containing iron and magnesium. This type of soil is found in Maharashtra and parts of Madhya Pradesh, Gujarat and Andhra Pradesh.

3. Alluvial soil:
It is a loamy soil which contains abundant amount of water in it. This is very fertile soil. This type of soil is very suitable for the production of rice and wheat. This soil is found in the plains of northern India.

4. Desert soil:
It is grey to brown in colour. The soil is sandy and porous, and cannot hold much water. This soil is found in Rajasthan and Gujarat.

5. Mountain soil:
It has the highest humus content among all soils in India. These soils are highly, fertile. This soil is found in the Himalyan region and the north – eastern parts of India.

6. Laterite soil:
It is red in colour and good for crops such as tea, coffee and coconut. This type of soil is typical of the rainy climate and rich in nutritive elements. This soil is found in Tamil Nadu, Andhra Pradesh, Assam and Orissa.

Question 3.
Write an essay on the importance of soil?
Answer:
Soil is an important part of our earth. It is not only a natural habitat for various worms and insects but plants also grow and absorb water and minerals for their growth and development in the soil.

1. For food, clothing and shelter:
By supporting growth of plants, the soil provides us with food. Much of our clothing, such as cotton and wool, can be traced to the soil. Plants also provide us fuel, paper, medicines and wood for use in furniture and for constructing houses.

2. For minerals:
We depend on the soil for minerals. Industries use the minerals dug out from the earth to extract metals such as gold, silver, iron, etc. and for use in thousands of industries that produce various useful things for us. Minerals, such as petroleum, natural gas, and coal obtained from soil provide us fuel and many other useful things.

3. For clay:
We depend on the soil for clay which is the raw material used to make tiles, bricks, procelain and pottery.

4. For water:
We depend on the soil for water. Water that seeps into the soil is stored underground as subsoil water. We use this water for drinking and other purposes.

Question 4.
Write a note on soil erosion?
Answer:
The process of water or wind carrying away soil from one place to another is called soil erosion. Following are the main reasons for soil erosion:

1. Erosion by natural forces:
Fast moving wind generally . carries away with it the top soil from the surface of the earth. Similarly, heavy rainfall creates flood situation and fast moving water washes away with it the top fertile soils from our fields which combinely result into erosion of soil.

2. Erosion by human activities. Various human activities are responsible for erosion of soil such as cutting of forests, improper and unscientific methods of agriculture and extensive use of grass lands.

Question 5.
What are the main causes for the erosion of soil?
Answer:
The main causes for the erosion of soil are:
1. Cultivation:
Continuous cultivation of land by only one type of crop further adds to the loss of soil fertility. Once the top of soil is lost, the sub-soil becomes a part of the layer for cultivation. This layer has less nutrient retention power, organic matter and aeration.

2. Deforestation:
It is due to increasing population and increasing industrialization. Deforestation leads to flooding and soil erosion. Forested land looses one tonne of soil per year whereas unforested land looses approximately 40 times more soil.

3. Floods:
The soil taken away by flood often gets deposited in ponds, rivers and lakes’. This causes the water to become muddy and reduces the depth of ponds, rivers and lakes. It also raises their bed due to silting, which has an adverse impact on aquatic life.

4.Overgrasing:
Animal overgrase the slopes that leads to removal of vegetation cover from the soil. All these animals pulverise the soil which is easily washed away in time of heavy rainfall. By overgrasing the soil is denuded of its protective covering of roots and grass.

Question 6.
How will you demonstrate that the vegetation prevents erosion of soil?
Answer:
Take two trays or baskets. Fill them with garden soil. Grow grass or some cereal in one of them and water it properly for a few days. Now keep both the trays in a slightly inclined position by placing a brick below their one side. Let the water fall on both the trays. You will find that the water that flows from the tray with vegetation contains less amount of soil particles in it. This is due to the fact that the roots of plants bind the soil and do not allow it to flow with water.

Question 7.
Differentiate between Black soils and Red soils?
Answer:
Black soils:

1. Rich in iron and magnesium derived from basaltic rocks.
2. Soil is clayey, contains dead organic matter and water; ideal for growing cotton and sugarcane.
3. In India, it is mainly found in Maharashtra, parts of Andhra Padesh, Madhya Pradesh and Gujarat.

Red soils:

1. Red colour is due to the presence of iron oxide.
2. Poor in humas but cannot be made fertile by adding manure or fertilizers.
3. In India, it is found in interior regions of Kerala and Tamil Nadu, Southern Karnataka, Andhra Pradesh, Orissa, Eastern Madhya.

Question 8.
What are the human activities responsible for soil erosion?
Answer:
The various human activities responsible for soil erosion are:

1. Cutting of forests:
With the increase in population and civilisation, deforestation started. Deforestation disturbed the natural habitat of wild animals and at the same time, it enchanced the process of soil erosion.

2. Improper and unscientific methods of agriculture:
Improper and unscientific methods of agriculture also increase the rate of soil erosion.

3. Extensive use of grass lands:
Extensive use of grass lands due to overgrazing by cattle also reduces grass and other, vegetation on the earth which causes erosion of soil.

MP Board Class 7th Science Solutions

MP Board Class 7th Science Solutions Chapter 8 Winds, Storms and Cyclones

Winds, Storms and Cyclones Intext Questions

Question 1.
I wonder why the winds shown in the figure are not in the exact north – south direction?

Answer:
The winds would have flown in the north – south direction from north to south or from south to north. A change in direction from however, caused by the rotation of the earth.

Question 2.
I want to know what these winds do for us?
Answer:
The winds from the oceans carry water and bring rain. It is a part of the water cycle.

Activities

Activity – 1
Blow the balloons:
Take two balloons of approximately equal size. Put a little water into the balloons. Blow up both the balloons and tie each one to a string. Hang the balloons 8 – 10 cm apart on a cycle spoke or a stick. Blow in the space between the balloons.

Question 1.
What did you expect? What happens?
Answer:
We expected that balloons would move apart. But the balloons come closer.

Activity – 2
Can you blow and lift?
Hold a strip of paper, 20 cm long and 3 cm wide, between your thumb and forefinger as shown in the paper. Paheli Thinks that the strip will be lifted up. Boojho thinks that the strip will bend down.

Question 1.
What do you think Will happen to the paper?
Answer:
Paper strip will be lifted up.

Question 2.
Were the observations along the lines you thought?
Answer:
Yes.

Question 3.
Do you get the feeling that the increased wind speed is accompanied by a reduced air pressure?
Answer:
Yes.

Activity – 3
Take two paper bags or empty paper cups of the same size. Hang the two bags in the inverted position on the two ends of a metal or wooden stick. Tie a piece of thread in the middle of the stick. Hold the stick by the thread (See Fig.) as in a balance. Put a burning candle below one of the bags as shown in the figure. Observe what happens.

Question 1.
Why is the balance of the bags disturbed?
Answer:
The bag below which the candle is lighted, is pushed up by the rising hot air from above the candle flame.

Question 2.
Does this activity indicate that warm air rises up?
Answer:
Yes.

Question 3.
Does the disturbance of the balance suggest that the warm air is lighter than the cold air?
Answer:
Yes.

Winds, Storms and Cyclones Text Book Exercises

Question 1.
Fill the missing word in the blank spaces in the following statements:

1. Wind is ……………. air.
2. Winds are generated due to ……………. heating on the earth.
3. Near the earth’s surface ……………. air rises up whereas air comes down.
4. Air moves from a region of ……………. pressure to a region of pressure.

Answer:

1. Moving
2. Uneven
3. Warm, cooler
4. High, low.

Question 2.
Suggest two methods to find out wind direction at a given place?
Answer:

1. By wind direction indicator.
2. By watching the direction of movement of a paper released in air.

Question 3.
State two experiences that made you think that air exerts pressure (other than those given in the text).
Answer:

1. Compressed air is used in the brake system for stopping trains.
2. Blowing air in a balloon makes it expand.

Question 4.
You want to buy a house. Would you like to buy a house having windows but no ventilators ? Explain your answer.
Answer:
No, a house which has no ventilators is not a healthy house to live in. Basically ventilators provide a path for warm air to go out of the rooms.

Question 5.
Explain why holes are made in hanging banners and hoardings?
Answer:
We know that air exerts pressure, so that due to this pressure banners and hoardings flutter when the wind is blowing. The holes are made in the banners and hoardings as wind pass through that holes and they does not become loose and fall down.

Question 6.
How will you help your neighbours in case cyclone approaches your village/town?
Answer:
I will help by following ways:

1. By warning everyone about the coming danger.
2. Searching for shelter.
3. Moving people fast to safe places.
4. Managing first aid facility.

Question 7.
What planning is required in advance to deal with the situation created by a cyclone?
Answer:
The following planning is required in advance to deal with the situation created by a cyclone:

1. Listening carefully to warnings being transmitted on TV and radio.
2. Setting up cyclone warning system,
3. Moving to cyclone shelter.
4. Storing food in water – proof bags.
5. Keeping an emergency kit ready.

Question 8.
Which one of the following place is unlikely to be affected by a cyclone.

1. Chennai
2. Mangaluru (Mangalore)
3. Amritsar
4. Puri.

Answer:
3. Amritsar.

Question 9.
Which of the statements given below is correct?

1. In winter the winds flow from the land to the ocean.
2. In summer the winds flow from the land towards the ocean.
3. A cyclone is formed by a very high – pressure system with very high – speed winds revolving around it.
4. The coastline of India is not vulnerable to cyclones.

Answer:
1. In winter the winds flow from the land to the ocean.

Extended Learning – Activities and Projects

Question 1.
You can perform the Activity 8.5 (of textbook) in the chapter slight differently at home. Use two plastic bottles of the same size. Stretch one balloon on the neck of each bottle. Keep one bottle in the sun and the other in the shade. Record your observations. Compare these observations and the result with those of Activity 8.5 of text book
Answer:
Do yourself.

Question 2.
You can make your own anemometer?
Answer:
Collect the following items:
4 small paper cups (used ice cream cups), 2 strips of cardboard (20 cm long and 2 cm wide), gum, stapler, a sketch pen and a sharpened pencil with eraser at one end. Take a scale draw crosses on the cardboard strips as shown in the Fig. (a). This will give you the centres of the strips.

Fix the strips at the centre, putting one over the other so that they make a plus (+) sign. Now fix the cups at the ends of the strips. Colour the outer surface of one cup with a marker or a sketch pen. All the 4 cups should face in the same direction.

Push a pin through the centre of the strips and attach the strips and the cups to the eraser of. the pencil. Check that the strips rotate freely when you blow on the cups. Your anemometer is ready. Counting the number of rotations per minute will give you an estimate of the speed of the wind.

To observe the changes in the wind speed, use it at different places and different times of the day. If you do not have a pericil with attached eraser you can use the tip of a ball pen. The only condition is that the strips should rotate freely. Remember that this anemometer will indicate only speed changes. It will not give you the actual wind speed.

Question 3.
Collect articles and photographs from newspapers and magazines about storms and cyclones. Make a story on the basis of what you learnt in this chapter and the matter collected by you?
Answer:
Do with the help of your subject teacher.

Question 4.
Suppose you are a member of a committee, which is responsible for creating development plan of a coastal state. Prepare a short speech indicating the measures to be taken to reduce the suffering of the people caused by cyclones?
Answer:
Do with the help of your subject teacher.

Question 5.
Interview eyewitness to collect the actual experience of people affected by a cyclone?
Answer:
Do with the help of your subject teacher.

Question 6.
Take an aluminium tube about 15 cm long and 1 to 1.5 cm in diameter. Cut slice of a medium – sized potato about 2 cm thick. Insert the tube in the slice, press it, and rotate it 2 – 3 times. Remove the tube. You will find a piece of potato fixed in the tube like a piston head. Repeat the same process with the other end of the tube. Now you have the tube with both ends closed by potato pieces with an air column in between.

Take a pencil with one end unsharpened. Place this end at one of the pieces of potato. Press it suddenly to push the potato piece in the tube. Observe what happens. The activity shows rather dramatically how increased air pressure can push things.
Answer:
Do yourself.

Winds, Storms and Cyclones Additional Important Questions

Objective Type Questions

Question 1.
Choose the correct alternative:

Question (i)
A storm is marked by –
(a) Strong winds
(b) Rain
(c) Thunder the lightning
(d) All the above.
Answer:
(d) All the above.

Question (ii)
The moving air is called –
(a) Wind
(b) Strong winds
(c) Storm
(d) None of these.
Answer:
(a) Wind

Question (iii)
The amount of water on the earth remains more or less the same because of –
(a) Thunder
(b) Storm
(c) Flood
(d) Water cycle.
Answer:
(d) Water cycle.

Question (iv)
The word monsoon is derived from –
(a) Arabic word
(b) English word
(c) Hindi word
(d) Urdu word.
Answer:
(a) Arabic word

Question (v)
The diameter of the eye of the cyclone varies from –
(a) 10 km to 15 km
(b) 10 km to 20 km
(c) 10 km to 30 km
(d) 10 km to 40 km.
Answer:
(c) 10 km to 30 km

Question (vi)
A violent tornado can travel at speeds of about –
(a) 200 km/h
(b) 300 km/h
(c) 350 km/h
(d) None of these.
Answer:
(b) 300 km/h

Question 2.
Fill in the blanks :

1. Orissa was hit by a cyclone with wind speed of 200 km/h on …………….
2. On 29 October, 1999, a second cyclone with wind speed of ……………. hit Orissa again.
3. The greater the difference in pressure, the ……………. the air moves.
4. The worm air is lighter than the ……………. air.
5. At the poles, the air is colder than that at latitudes about ……………. degrees.
6. The word monsoon is derived from the Arabic word …………….
7. Clouds bring ……………..
8. Farmers in our country depend mainly on rains for their …………….
9. A large cyclone is a violently rotating mass of ………… in the atmosphere.
10. A tornado is a ……………. funnel shaped cloud that reaches from the sky to the ground.

Answer:

1. 18 October 1999
2. 260 km/h
3. Faster
4. Cold,
5. 60
6. Mausam
7. Rain
8. Harvests
9. Air
10. Dark.

Question 3.
Which of the following statements are true (T) or false (F):

1. The cyclone affected agriculture, communication, transport and electricity supply.
2. On heating the air expands and occupies more space
3. In winter, the direction of the wind flow gets reversed.
4. The winds from the oceans carry water arid bring rain.
5. Water cycle is not a continuous phenomenon.
6. Thunderstorms are caused by violent air current inside the cumulus clouds.
7. The cyclones are called hurricane in America.
8. The storms are called typhoons in China.
9. Uneven heating on the earth is the main cause of wind movement.
10. We must stand under a high-rise building or a tree when caught in a thunderstorm.
11. Tropical cyclones occur throughout the year.
12. Lightning, rains and storms are always harmful for the earth.

Answer:

1. True (T)
2. True (T)
3. True (T)
4. True (T)
5. False (F)
6. True (T)
7. True (T)
8. True (T)
9. True (T)
10. False (F)
11. False (F)
12. False (F)

Question 4.
Match the items in Column A with Column B:

Answer:

(i) (b)
(ii) (c)
(iii) (d)
(iv) (a).

Winds, Storms and Cyclones Very Short Answer Type Questions

Question 1.
What is a wind?
Answer:
The moving air is called wind.

Question 2.
Define the term cycle?
Answer:
A cycle is an event or phenomenon which repeats it selfs after sometime.

Question 3.
Define the term evaporation?
Answer:
The process of changing water from its liquid form to its vapour is known as evaporation.

Question 4.
When you fly a kite, does the wind coming from your back help?
Answer:
Yes.

Question 5.
If you are in a boat, is it easier to row it if there is wind coming from behind you?
Answer:
Yes.

Question 6.
Define tornadoes?
Answer:
A tornado is a dark funnel shaped cloud that reaches from the sky to the ground. In our country tornadoes are not very frequent.

Question 7.
Which region gets maximum sunlight?
Answer:
Regions close to the equator get maximum sunlight.

Question 8.
What do you mean by the “eye” of a storm?
Answer:
The centre of a cyclone is calm area. It is called the eye of the storm.

Question 9.
Can you imagine what would happen if high speed winds blow over the roofs of buildings?
Answer:
If the roofs were weak, they would be lifted and blown away.

Question 10.
What do you mean by “hurricane”?
Answer:
“Hurricane” is the term used for storm in West Indies and America.

Question 11.
When is cyclone alert issued?
Answer:
A cyclone alert or cyclone watch is issued 48 hours in advance of any expected storm.

Question 12.
Which factors contribute to the development of cyclone?
Answer:
Facters like wind speed, wind direction, humidity and temperature contribute to the development of cyclones.

Question 13.
When is cyclone warning issued?
Answer:
A cyclone warning is issued 24 hours in advance.

Question 14.
Why smoke always rises up?
Answer:
Smoke is hotter than air, so it is also lighter than air. That is why smoke always moves up.

Question 5.
How do “high – speed winds” harm us ?
Answer:
High – speed winds accompanying a cyclone can damage houses, telephones and other communication systems, trees, etc. causing tremendous loss of life and property.

Question 16.
What is “beaufort scale”?
Answer:
The number and name of a wind is determined by the speed at which it flows on an internationally accepted scale, called beaufort scale.

Question 17.
Is our body a conductor?
Answer:
Yes.

Question 18.
How are high building protected from lightning?
Answer:
High buildings are protected from lightning by fixing lightning conductor on the building.

Winds, Storms and Cyclones Short Answer Type Questions

Question 1.
How is storm caused?
Answer:
When the wind blows gently, it is called a breeze. But, when it blows very fast it cause storm. Storm may be defined as something taking place in the weather of a violent nature. At sea, a storm may be a strong wind or gale. On land, a storm usually means a weather situation marked by heavy rain and often with strong winds, lightning and thunder.

Question 2.
Explain the structure of a tornado?
Answer:
The diameter of a tornado can be as small as a metre and as large as a kilometer, or even wider. The funnel of a tornado sucks dust, debris and everything near it at the base (due to low pressure) and throws out near the top.

Question 3.
How is lightning useful in nature?
Answer:
Lightning is useful in nature because during lightning in tense heat and high temperature are produced. As a result, nitrogen combines with oxygen to form its oxides. These oxides of nitrogen further get dissolved in water to form a dilute solution of nitric acid that comes to the ground with rain. This is how nature provides nitrogenous compounds to plants that are important for their growth.

Question 4.
How are lightning and thunder caused?
Answer:
When two oppositily charged clouds are near each other, the air between them becomes good conductor because charges begin, to move in air very speedily. The presence of electric charges in very large quantities in the air causes to appear as sleaks of lightning and thunder.

Question 5.
Explain the terms thunderstorms and cyclones.
Answer:
Thunderstorms develop in hot, humid tropical areas like India very frequently. The rising temperatures produce strong upward rising winds. These winds carry water droplets upwards, where they freeze, and fall down again. The swift movement of the falling waterd roplets along with the rising air create lightning and sound. It is this event that we call a thunderstorm.

Question 6.
Suggest precautios if a storm is accompanied by lightning?
Answer:
If a storm is accompanied by lightning, we must take the following precautions:

1. Do not take shelter under an isolated tree. If you are in a forest take shelter under a small tree. Do not lie on the ground,
2. Do not take shelter under an umbrella with a metallic end.
3. Do not sit near a window. Open garages, storage sheds, metal sheds are not safe places to take shelter.
4. A car or a bus is a safe place to take shelter.
5. If you are in water, get out and go inside a building.

Question 7.
Suggest some effective safety measures for cyclone.
Answer:
Some Effective Safety Measures:

1. A cyclone forecast and warning service.
2. Rapid communication of. warnings to the Government agencies, the ports, fishermen, ships and to the general public.
3. Construction of cyclone shelters in the cyclone prone areas, and Administrative arrangements for moving people fast to safer places.

Winds, Storms and Cyclones Long Answer Type Questions

Question 1.
How does a thunderstorm becomes a cyclone?
Answer:
Before cloud formation, water takes up heat from the atmosphere to change into vapour. When water vapour changes back to liquid form as raindrops, this heat is released to the atmosphere. The heat released to the atmosphere warms the air around. The air tends to rise and causes a drop in pressure. More air rushes to the centre of the storm. This cycle is repeated. The chain of events ends with the formation of a very low – pressure system with very high – speed winds revolving around it. It is this weather condition that we call a cyclone. Factors like wind speed, wind direction, temperature and humidity contribute to the development of cyclones.

Question 2.
Define the structure of a cyclone?
Answer:
Structure of a cyclone:
The centre of a cyclone is a calm area. It is called the eye of the storm. A large cyclone is a violently rotating mass of air in the atmosphere, 10 to 15 km high. The diameter of the eye varies from 10 to 30 km. It is a region free of clouds and has light winds. Around this calm and clear eye (See Fig.), there is a cloud region of about 150 km in size.

In this region there are high – speed winds (150-250 km/h) and thick clouds with heavy rain. Away from this region the wind speed gradually decreases. The formation of a cyclone is a very complex process.

Question 3.
With a neat diagram show the formation of a cyclone.
Answer:

Question 4.
Describe the action taken by the people and some precautions if you are staying in a cyclone hit area?
Answer:
Action on the part of the people:

1. We should not ignore the warnings issued by the meteorological department throught TV, radio, or newspapers.
2. We should make necessary arrangements to shift the essential household goods, domestic animals and vehicles, etc. to safer places.
3. We should avoid driving on roads through standing water, as floods may have damaged the roads.
4. We should keep ready the phone numbers of all emergency sendees like police, fire brigade, and medical centres.

Some precautions, if you are staying in a cyclone hit area:

1. Do not drink water that could be contaminted. Always store drinking water for emergencies.
2. Do not touch wet switches and fallen power lines.
3. Do not go out just for the sake of fun.
4. Do not pressurise the rescue force by making undue demands.
5. Cooperate and help your neighbours and friends

Question 5.
Show the phenomena that lead to the formation of clouds and falling of rain and creation of storms and cyclones with the help of a flow diagram or a flow chart.
Answer:

Question 6.
On a map, show the regions near the equator where cyclones form.
Answer:

MP Board Class 7th Science Solutions

MP Board Class 7th Science Solutions Chapter 7 Weather, Climate and Adaptations of Animals of Climate

Weather Climate and Adaptations of Animals of Climate  Intext Questions

Question 1.
I wonder who prepares the wheather report?
Answer:
The weather reports are prepared by the Meteorological Department of the Government.

Question 2.
I wonder why weather changes so frequently?
Answer:
Because factors affecting weather like temperature, humidity, etc. vary frequently.

Question 3.
What is the source of whether in the first place?
Answer:
All changes in the weather are caused due to sun.

Question 4.
Do fishes and butterflies also migrate like birds?
Answer:
No.

Activity
Fill all the columns according to the data in the chart that you have prepared.
Answer:
Table
Weather data of a week

(Rainfall may not be recorded for all the days since it may not rain everyday.)

Weather, Climate and Adaptations of Animals of Climate Text Book Exercises

Question 1.
Name the elements that determine the weather of a place?
Answer:
The day – to – day condition of the atmosphere at a place with respect to the temperature, rainfall, humidity, wind – speed, etc., is called the weather at that place.

Question 2.
When are the maximum and minimum temperature likely to occur during the day?
Answer:
The maximum temperature of the day occurs generally in the afternoon while the minimum temperature occurs in the early morning.

Question 3.
Fill in the blanks:

1. The average weather taken over a long time is called …………..
2. A place receives very little rainfall and the temperature is high throughout the year, the climate of that place will be ……………. and
3. The two regions of the earth with extreme climatic conditions are ………….. and ……………

Answer:

1. Climate of the place
2. Hot, dry
3. Tropical, polar regions.

Question 4.
Indicate the type of climate of the following areas:

1. Jammu and Kashmir –
2. Kerala –
3. Rajasthan –
4. North – east India –

Answer:

1. Moderately hot and moderately wet climate.
2. Very hot and wet climate.
3. Hot and dry climate.
4. Wet climate.

Question 5.
Which of the two changes frequently weather or climate?
Answer:
Weather.

Question 6.
Following are some of the characteristics of animals:

1. Diets heavy on fruits
2. White fur
3. Need to migrate
4. Loud voice
5. Sticky pads on feet
6. Layer of fat under skin
7. Wide and large paws
8. Bright colours
9. Strong tails
10. Long and Large beak.

For each characteristic indicate whether it is adaptation for tropical rainforests or polar regions. Do you think that some of there characteristics can be adapted for both regions?
Answer:

1. Tropical rainforests
2. Polar region
3. Polar region
4. Tropical rainforesl
5. Tropical rainforests
6. Polar region
7. Polar region
8. Tropical rainforets
9. Tropical rain.forests
10. Tropical rainfore’t

Question 7.
The tropical rainforest has a large population of animals. Explain why it is so?
Answer:
Tropical rain are found in Western Ghats and Assam in India, South – east Asia, central America and Central Africa. Because of continuous warmth and rain, this region supports wide variety of plants and animals. The major types of animals living in the rainforests are apes, gorillas, monkeys, tigers, lions, leopards, lizards, elephants, insects, birds and snakes.

The climate conditions in rainforests are highly suitable for supporting an enormous number and variety of animals. Thus, we can say that because of the hospitable climate conditions huge populations of plants and animals are found in the tropical rainforests.

Question 8.
Explain, with examples, why we find animals of certain kind living in particular climatic conditions?
Answer:
Animals are adapted to survive in the conditions in which they live. Animals living in very cold and hot climate must possess special features to protect themselves against the extreme cold or heat. Polar bears have white fur so that they are not easily visible in the snowy white background. It protects them from their predators. It also helps them in catching their prey. To protect them from extreme cold, they have two thick layers of fur.

They also have a layer of fat under their skin. In fact, they are so well – insulated that they have to move slowly and rest often to avoid getting overheated. Physical activities on warm days necessitate cooling. So, the polar bear goes for swimming. It is a good swimmer. Its paws are wide and large, which help it not only to swim well but also walk with ease in the snow. While swimming under water, it can close its nostrils and can remain under water for long durations.

It has a strong sense of smell so that it can catch its prey for food. Another well – known animal living in the polar regions is the penguin (Fig.). It is also white and merges well wTith the white background. It also has a thick skin and a lot of fat to protect it from cold. You may have seen pictures of penguins huddled together. This they do to keep warm.

Question 9.
How do elephant living in the tropical rainforest adapt itself?
Answer:
The elephant has adapted to the conditions of rainforests in many remarkable ways. Look at its trunk. It uses it as a nose because of whjch it has a strong sense of smell. The trunk is also used by it for picking up food. Moreover, its tusks are modified teeth. These can tear the bark of trees that elephant loves to eat.

So, the elephant is able to handle the competition for food rather well. Large ears of the elephant help it to hear even very soft sounds. They also help the elephant to 4 keep cool in the hot and humid climate of the rainforest.

Choose the correct option which answers the following question:

Question 10.
A carnivore with stripes on its body moves very fast while catching its prey. It is likely to be found in

1. Polar regions
2. Deserts
3. Oceans
4. Tropical rainforests.

Answer:
4. Tropical rainforests.

Question 11.
Which features adapt polar bears to live in extremely cold climate?

1. A white fur, fat below skin, keen sense of smell.
2. Thin skin, large eyes, a white fur.
3. A long tail, strong claws, white large paws.
4. White body, paws for swimming, gills for respiration.

Answer:
1. A white fur, fat below skin, keen sense of smell.

Question 12.
Which option best describes a tropical region?

1. Hot and humid
2. Moderate temperature, heavy rainfall
3. Cold and humid
4. Hot and dry.

Answer:
1. Hot and humid.

Extended Learning – Projects and Activities

Question 1.
Collect weather reports of seven successive days in the winter months (preferably December). Collect similar reports for the summer months (preferably June). Now prepare a table for sunrise and sunset times as shown:
Table

Try to answer the following questions:

1. Is there any difference in the time of sunrise during summer and winter?
2. When do you find that the sun rises earlier?
3. Do you also find any difference in the time of sunset during the month of June and December?
4. When are the days longer?
5. When are the nights longer?
6. Why are the days sometimes longer and sometimes shorter?
7. Plot the length of the days against the days chosen in June and December?

Answer:

1. Yes.
2. Sunrises earlier during summer.
3. Yes, sunsets earlier during winter.
4. During summer, the days are longer.
5. During winter, the nights are longer.
6. Earth revolves around the sun. During different times, the angle of earth with the sun changes. This causes the difference in length of day and night.
7. Length.

Question 2.
Collect information about the Indian Meteorological Department. If possible visit its website: http//www.imd.gov.in. Write a brief report about the things this department does.
Answer:
Do with the help of your subject teacher.

Weather, Climate and Adaptations of Animals of Climate Additional Important Questions

Objective Type Questions

Question 1.
Choose the correct alternative:

Question (i)
The weather reports are prepared by the –
(a) Meteorological Department of the Government
(b) Agricultural Department of the Government
(c) Radio and TV Department of the Government
(d) None of these.
Answer:
(a) Meteorological Department of the Government

Question (ii)
The climate of the north – east is –
(a) Hot
(b) Wet
(c) Cold
(d) Dry.
Answer:
(b) Wet

Question (iii)
The climate of the western region is –
(a) Hot
(b) Wet
(c) Dry
(d) Hot and dry.
Answer:
(d) Hot and dry.

Question (iv)
The lion – tailed macaque lives in the rainforests of –
(a) Western Ghats
(b) Eastern Ghats
(c) Both (a) and (b)
(d) None of these.
Answer:
(a) Western Ghats

Question (v)
Which are of the following is a migratory bird –
(a) Penguin
(b) Peacock
(c) Crow
(d) Siberian crane.
Answer:
(d) Siberian crane.

Question 2.
Fill in the blanks:

1. The temperature, humidity and other factors are called the ……………. of the weather.
2. Rainfall is measured by an instrument called the …………….
3. All changes in the weather are caused by …………….
4.  ……………. Record the weather every day.
5. The polar regions are situated near the …………….
6. Musk oxen, foxes, seals, etc. are living in the ……………. regions.
7. The tropical region has generally a ……………. climate.
8. Animals are adapted to the conditions in which they …………….
9. Penguins lives in ……………. regions.
10. The beard ape lives in the rainforests of …………….

Answer:

1. Elements
2. Rain gauge
3. Sun
4. Meteorologists
5. Poles
6. Polar
7. Hot
8. Live
9. Very cold
10. Western Ghats.

Question 3.
Which of the following statements are true (T) or false (F):

1. The weather is generally not the same on any two days and week after week.
2. The camel is called the ship of the desert.
3. The times of sunrise and sunset also change during the year.
4. The climate of the Kerala is very cold for most part of the year
5. Penguins lives in very cold.
6. Animals are adapted to the conditions in which they live.
7. All the changes in the weather are driven by the sun.
8. Migration is another means to escape the harsh, cold conditions.
9. Polar bears are found in Indian tropical rainforests.
10. The winter sleep of animals is called migration.

Answer:

1. True (T)
2. True (T)
3. True (T)
4. False (F)
5. True (T)
6. True (T)
7. True (T)
8. True (T)
9. False (F)
10. False (F).

Question 4.
Match the items in Column A with Column B:

Answer:

(i) (b)
(ii) (d)
(iii) (a)
(iv) (c)

Weather, Climate and Adaptations of Animals of Climate vert short  Answer Type Questions

Question 1.
Who prepares the weather report?
Answer:
The weather reports are prepared by the Metreological Department of the Government.

Question 2.
What do you mean by weather?
Answer:
The day – to – day condition of the atmosphere at a place with respect to the temperature, rainfall, wind speed, humidity, is called the weather of that place.

Question 3.
What do you mean by climate?
Answer:
The average weather pattern taken over a long time, say 25 years, is called the climate of the place.

Question 4.
When is the climate of a place called hot and wet?
Answer:
If there is heavy rainfall on most of the days as well as the temperature is high in the same place, then we can say that the climate of that place is hot and wet.

Question 5.
When is the climate of a place called hot?
Answer:
If the temperature at a place is high most of the time, then we say that the climate of that place is hot.

Question 6.
Why do some places have hotter climate than others?
Answer:
The places nearer to the equator are usually hotter. This is because the sim’s rays are more concentrated near the equator than they are farther North or South.

Question 7.
Which causes the changes in weather?
Answer:
Sun.

Question 8.
Name the location in India where climate is hot and dry?
Answer:
Rajasthan.

Question 9.
Name the location in India where climate is wet.
Answer:
North – east.

Question 10.
Define raingauge.
Answer:
Rainfall is measured by an instrument called the raingauge.

Question 11.
Name two animals found in cold climate?
Answer:
Polar bear and Penguins.

Question 12.
Name two animals found in hot and humid climate.
Answer:
Beard ape and Red – eyed frog.

Question 13.
Name two deserts animal.
Answer:
Camel and snake.

Question 14.
Where does penguin live?
Answer:
Penguin lives in very cold places.

Question 15.
What makes penguins good swimmers?
Answer:
Penguin’s bodies are streamlined and their feet have webs, making them good swimmers.

Question 16.
How are the paws of a polar bear?
Answer:
Wide and large.

Question 17.
Can a polar bear live happily on land?
Answer:
No, it lives happily where the land is fully covered with snow.

Question 18.
Where do the elephant live ?
Answer:
Elephant lives in forest.

Question 19.
Name two countries where the tropical rainforests are found?
Answer:
India and Brazil.

Question 20.
Name two countries where polar regions are found?
Answer:
Sweden and Canada.

Question 21.
Name four countries in polar region?
Answer:
Norway, Iceland, Canada and Greenland.

Question 22.
Name the major types of animals living in rainforest?
Answer:
The major types of animals living in the rainforests are apes, lions, tigers, monkeys, gorillas, elephants, leopards, snakes, birds and lizards.

Question 23.
Where do the following animals live?

1. Fish
2. Monkeys
3. Snakes

Answer:

1. In water
2. On land and trees
3. On land and water.

Question 24.
Name any two animals which are active during night?
Answer:
Owl and Bat.

Question 25.
Name the bird from Siberia that comes to India?
Answer:
Siberian Crane.

Weather, Climate and Adaptations of Animals of Climate Short Answer Type Questions

Question 1.
Differentiate between weather and climate?
Answer:
Difference between weather and climate:

Weather:
The day – to – day condition of the atmosphere at a place with respect to the temperature, rainfall, windspeed, humidity, etc. is called the weather at that place.

Climate:
The average weather pattern taken over a long time, say 25 years, is called the climate of that place.

Question 2.
Write a short note on the sun?
Answer:
All changes in the weather are caused by the sun. The sun is a huge sphere of hot gases at a very high temperature. The distance of the sun from us is very large. Even then the energy sent out by the sun is so huge that it is the source of all heat and light on the earth. So, the sun is the primary source of energy that causes changes in the weather.

Energy absorbed and reflected by the earth’s surface, oceans and the atmosphere play important roles in determining the weather at any place. If you live near the sea, you would have realised that the weather at your place is different from that of a place in a desert, or near a mountain.

Question 3.
How do penguins adapt with polar climate?
Answer: Penguins are white and merge well with the white background. They also have a thick skin and a lot of fat to protect it from cold. Penguins huddle together. This they do to keep warm. Further, their bodies are streamlined and their feet have webs, making them good swimmers.

Question 4.
How is camel adapted to live in desert?
Answer:
Camel lives in desert. It has long legs which help it to lift its body above the ground. So, camel is able to avoid direct contact with the hot ground. Camel drinks more than 50 litres of water at a time. Camel store the water in his body. So that it lives without water for a longer time. Due to its thick skin, transpiration of water is also prevents. That’s why camel is suited to live in desert.

Question 5.
How are fishes adapted to live in water?
Answer:
Fishes are best suited to live in water. They have structure like a boat, which help them in swimming in water. They have gills from which they get food and oxygen. The body of fishes contain different types of fins which help them for swimming in water.

Question 6.
What is the climate of polar regions?
Answer:
The polar regions present an extreme climate. These regions are covered with snow and it is very cold for most part of the year. For six months the sun does not set at the poles while for the other six months the sun does not rise. In winters, the temperature can be as low as _–37°C. Animals living there have adapted to these severe conditions.

Question 7.
Where the polar regions are situated? Name some of the countries that belong to the polar regions. Also name the some countries where the tropical rainforests are found.
Answer:
The polar regions are situated near the poles, i.e., north pole and south pole. Some well – known countries that belong to the polar regions are Canada, Greenland, Iceland, Norway, Sweden, Finland, Alaska in U.S.A. and Siberian region of Russia. Some countries where the tropical rainforests are found are India, Malaysia, Indonesia, Brazil, Republic of Congo, Kenya, Uganda, and Nigeria.

Question 8.
Write the features of lion – tailed macaque?
Answer:
The lion – tailed macaque (also called Beard ape) lives in the rainforests of Western Ghats. Its most outstanding feature is the silver – white mane, which surrounds the head from the cheeks down to its chin. It is a good climber and spends a major part of its life on the tree. It feeds mainly on fruits. It also eats seeds, young leaves, stems, flowers and buds. This beard ape also searches for insects under the bark of the trees. Since it is able to get sufficient food on the trees, it rarely comes down on the ground.

Weather, Climate and Adaptations of Animals of Climate Long Answer Type Questions

Question 1.
Answer:

Question 2.
Write a note about “climate of the tropical rainforests”?
Answer:
The tropical region has generally a hot climate because of its location around the equator. Even in the coldest month the temperature is generally higher than about 15°C. During hot summers, the temperature may cross 40°C. Days and nights are almost equal in length throughout the year. These regions get plenty of rainfall. An important feature of this region is the tropical rainforests. Tropical rainforests are found in Western Ghats and Assam in India, Southeast Asia, Central America and Central Africa. Because of continuous warmth and rain, this region supports wide variety of plants and animals. The major types of animals living in the rainforests are monkeys, apes, gorillas, lions, tigers, elephants, leopards, lizards, snakes, birds and insects.

Question 3.
For which animals the climatic conditions in rainforests are highly suitable?
Answer:
The climatic conditions in rainforests are highly suitable for supporting an enormous number and variety of animals. Since the numbers are large, there is intense competition for food and shelter. Many animals are adapted to living on the trees. Red – eyed frog (Fig. (a)) has developed sticky pads on its feet to help it climb trees on which it lives. To help them live on the trees, monkeys (Fig. (b)) have long tails for grasping branches. Their hands and feet are such that they can easily hold on to the branches.

MP Board Class 7th Science Solutions

MP Board Class 7th Science Solutions Chapter 6 Physical and Chemical Changes

Activities

Activity 1
Make a list of eight changes you have noticed from your surroundings.
Answer:
The changes are as:

1. Motion of fan
2. Lighting of a tubelight
3. Vaporisation of water
4. Melting of ice
5. Sound produced by radio
6. Blooming of flower
7. Changing of day and night
8. Changing of the shape of sun.

Activity 2
Try to indentify changes that you observe around you as physical or chemical changes.
Answer:

Physical and Chemical Changes Text book Exercises

Question 1.
Classify the changes involved in the following processes as physical or chemical changes?

1. Photosynthesis
2. Dissolving sugar in water
3. Burning of coal
4. Melting of wax
5. Beating aluminium to make aluminium foil
6. Digestion of food

Answer:

1. Chemical change
2. Physical change
3. Chemical change
4. Physical change
5. Physical change
6. Chemical change.

Question 2.
State whether the following statements are true or false. In case a statement is false, write the corrected statement in you notebook?

1. Cutting a log food into pieces is a chemical change. (T/F)
2. Formation are from leaves is a physical change. (T/F)
3. Iron pipes coated with zinc do not get rusted easily. (T/F)
4. Iron and rust are the same substances. (T/F)
5. Condensation of steam is not a chemical change. (T/F)

Answer:

1. False (F)
2. False (F)
3. True (T)
4. True (T)
5. True (T)

Question 3.
Fill in the blanks in the following statements:

1. When carbon dioxide is passed through lime water, it turns milky due to the formation of ……………
2. The chemical name of baking soda is ……………
3. Two methods by which rusting of iron can be prevented are …………… and ……………
4. Changes in which only …………… properties of a substance change are called physical changes.
5. Changes in which new substances are formed are called …………… changes.

Answer:

1. calcium carbonate
2. Sodium hydrogen carbonate
3. coating, galvanization
4. physical
5. chemical

Question 4.
When baking soda is mixed with lemon juice, bubbles are formed with the evolution of a gas. What type of changes is it? Explain.
Answer:
It is a chemical change. When baking soda is mixed with lemon juice, bubbles are formed with the evolution of a gas carbaon – dioxide.
Lemon juice + Baking soda Carbon dioxide + Lime water.

Question 5.
When a candle burns, both physical and chemical changes take place. Identify these changes. Give another example of a familiar process in which both the chemical and physical changes take place?
Answer:
Melting of wax is a physical change while burning of candle is a chemical change. Lightning torch bulb using dry cell is another example where both physical and chemical changes takes place. The lighting of the bulb is physical change while current from the dry cell is obtained by the chemical substances inside it.

This is chemical change because the chemicals in the cell get converted into new substances and hence the cell ultimately becomes useless.

Question 6.
How would you show that setting of curd is a chemical change?
Answer:
The conversion of milk into curd, i.e., setting of curd is a permanent as well as irreversible and lead to the production of a new substance. The curd is not be converted into milk. Thus, the formation of curd is a chemical change.

Question 7.
Explain why burning of wood and cutting it into small pieces are considered as two different types of changes.
Answer:
Burning of a wood is a chemical change because in addition to new products burning is always accompanied by production of heat. Cutting of wood into small pieces is a physical change because pieces of wood under went changes in size and no new substances is formed.

Question 8.
Describe how crystals of copper sulphate are prepared?
Answer:
Take a cupful of water in a beaker and add a few drops of dilute sulphuric acid. Heat the water. When it starts boiling add copper sulphate powder slowly while stirring continuiously (fig.). Continue adding copper sulphate powder, till no more powder can be dissolved. Filter the solution. Allow it to cool.

Do not disturb the solution when it is cooling. Look at the solution after some time. Can you see the crystals of copper sulphate? If not, wait for some more time. Crystals of copper sulphate slowly from at the bottom of the beaker.

Question 9.
Explain how painting of an iron gate prevents it from rusting?
Answer:
For rusting, iron must be in contact with both air and moisture. When iron gate is painteel the layer of paint cuts the contact between air, moisture and iron. Thus, it prevents rusting.

Question 10.
Explain why rusting of iron objects is faster in coastal areas than in deserts?
Answer:
The water of coastal areas containing many salts. The salt water makes the process of rust formation faster. Thus, rusting of iron objects is faster in coastal areas than deserts.

Question 11.
The gas we use in the kitchen is called liquified petroleum gas (LPG). In the cylinder it exist as a liquid. When it comes out from the cylinder it becomes a gas (Change A) then it burns (Change B). The following statements pertain to these changes. Choose the correct one.

1. Process – A is a chemical change.
2. Process – B is a chemical change.
3. Both processes – A and B are chemical changes.
4. None of these processes is a chemical change.

Answer:
3. Both processes – A and B are chemical changes.

Question 12.
Anaerobic bacteria digest animal waste and produce biogas (Change A). The biogas is then burnt as fuel (Change B). The following statements pertain to these changes. Choose the correct one.

1. Process – A is a chemical change.
2. Process – B is a chemical change.
3. Both processes – A and B are chemical changes.
4. None of these processes is a chemical change.

Answer:
3. Both processes – A and B are chemical changes.

Extended Learning – Activities and Projects

Question 1.
Describe two changes that are harmful. Explain why you consider them harmful. How can you prevent them?
Answer:
1. Spoilage of Food:
Food items when kept carelessly, get spoiled. This is a chemical change and obviously harmful for our health. Basically, the food is spoiled by microorganisms.

Preventation of Food Spoilage:
Microorganisms do not survive high or low temperature. So, food items stored in refrigerator do not spoil. Also, we should keep them covered, so that microorganism do not get any change to spoil them.

2. Rusting:
If a piece of iron is left in open for some time, it acquires a film of brownish substance. This substance is called rust and the process is called rusting.

Iron benches kept in parks, gardens and lawns, iron gates of parks, farm houses, houses; almost every article of iron, kept in open gets rusted.

The process of rusting can be represented by the following equation:
Iron (Fe) + Oxygen (O₂, from the air) + water (H₂O) → Rust (ironoxide, Fe₂O₃)
For rusting, the presence of both water (or water vapour) and oxygen is essential. Rusting is harmful because, it destorys the iron objects. Iron is the most widely used metal and so rusting is a serious problem.

Preventation of rusting:
It can be prevented by preventing iron things from coming in contact with water, oxygen, or both. One simple way is to apply a coat of paint or grease. In fact, these coats should be applied regularly to prevent rusting.

Another way is to deposit a layer of a metal like chromium or zinc on iron. This process is called galvanisation. Generally the iron pipes, which are used in our homes for water supply are galvanised to prevent rusting.

Question 2.
Take three glass bottles with wide mouths. Label them, A, B and C. Fill about half of bottle A with ordinary tap water. Fill bottle B with water which has been boiled for several minutes, to the same level as in A. In bottle C, take the same boiled water and of the same amount as in other bottles. In each bottle put a few similar iron nails so that they are completely under water. Add a teaspoonful of cooking oil to the water in bottle C so that it forms a film on its surface. Put the bottles away for a few days. Take out nails from each bottle and observe them. Explain your observations?
Answer:
The nails in bottle B rust a little, nails in bottle A are the most rusted and that is bottle C remain unchanged. For rusting both oxygen and water are necessary. Both of these factors are present in the bottle A, since oxygen is dissolved in water. In bottle B, water is boiled and hence dissolved air is removed. Due to lack of oxygen, iron nail does not rust much. In bottle C, the layer of oil present dissolution of air in the water and hence no rusting occurs.

Question 3.
Prepare crystals of alum.
Answer:
Take a cupful of water in a beaker and add a few drops of dilute sulphuric acid. Heat the water. When it starts boiling add copper sulphate powder slowly while stirring continuiously (fig.). Continue adding copper sulphate powder, till no more powder can be dissolved. Filter the solution. Allow it to cool.

Do not disturb the solution when it is cooling. Look at the solution after some time. Can you see the crystals of copper sulphate? If not, wait for some more time. Crystals of copper sulphate slowly from at the bottom of the beaker.

Question 4.
Collect information about the types of fuels used for cooking in you area. Discuss with your teachers/ parents/ others which fuels are less polluting and why?
Answer:
The different fuels used for cooking are wood, cow – dung cake, kerosene, biogas and LPG. Among all of these, biogas and LPG are least polluting. Both of these burn completely and do not give smoke. Also there is no residue i.e. ash after burning. Thus, these fuels are less polluting.

Physical and Chemical Changes Additional Important Questions

Objective Type Questions

Question 1.
Choose the correct alternative

Question (i)
Which of the following is not a chemical change –
(a) Digestion of food
(t) Burning of oaal
(c) Curdling of milk
(d) Melting Of ice.
Answer:
(d) Melting Of ice.

Question (ii)
Properties such as shape, size, colour and state of a sub-stance are called its –
(a) Chemical properties
(b) Physical properties
(c) Both (a) and (b)
(d) None of these.
Answer:
(b) Physical properties

Question (iii)
The substances formed as a result of chemical reaction are called –
(a) Materials
(b) Products
(c) Reactants
(d) ingredients.
Answer:
(b) Products

Question (iv)
Rusting of iron is a
(a) Slow reaction
(b) Fast reaction
(c) Both (a) and (b)
(d) None of these.
Answer:
(a) Slow reaction

Question (v)
Qutub minar was built more than years ago –
(a) 1600
(b) 1650
(c) 1700
(d) 1800.
Answer:
(a) 1600

Question 2.
Fill in the blanks:

1. A physical change is generally ……………..
2. A chemical change is also called a …………….. reaction.
3. Chemical changes are very important in our ……………..
4. Ozone layer protects us from the harmful …………….. radiation which come from the sun.
5. Oxygen is …………….. from ozone.
6. If the content of moisture in air is high, which means if it is more humid, rusting becomes ……………..
7. The process of depositing a layer of zinc on iron is called ……………..
8. Stainless steel does …………….. rust.
9. In chemical changes …………….. substances are produced.
10. Burning of coal, wood or leaves is a …………….. change.

Answer:

1. Reversible
2. Chemical
3. Lives
4. Ultraviolet
5. Different
6. Faster
7. Galvanisation
8. Hot
9. New
10. Chemical.

Question 3.
Which of the following statements are true (T) or false (F):

1. Conversion of milk into curd is a physical change.
2. A physical change is generally reversible.
3. On dissolving the ash in water it forms a new substance.
4. When carbon dioxide is passed throuth lime water, calcium carbonate is formed, which makes lime water milky.
5. Chemical changes are not important in our lives.
6. All new substances are formed as a result of chemical changes.
7. A medicine is the end product of a chain of chemical reactions.
8. Stainless steel is made by mixing iron with carbon and metals.

Answer:

1. False (F)
2. True (T)
3. True (T)
4. True (T)
5. False (F)
6. True (T)
7. True (T)
8. True (T).

Question 4.
Match the items in Column A with Column B:

Answer:

(i) (b)
(ii) (d)
(iii) (a)
(iv) (c)

Physical and Chemical Changes Very Short  Answer Type Question

Question 1.
Define a physical change.
Answer:
The change in which the identity of the substance does not change is called a physical change.

Question 2.
Give any one characteristic of a physical change.
Answer:
No new substance is formed as a result of physical change.

Question 3.
List two physical changes.
Answer:

1. Change of an iron bar to a magnet.
2. Melting of ice.

Question 4.
Complete the following:

1. In a physical change the state of the substance is ………….. if cause of the change is removed.
2. In a physical change only ……………… physical properties of the substance are

Answer:

1. Restored
2. Changed.

Question 5.
Define a chemical change.
Answer:
It is the change in which identity of the substance is changed and a new substance is formed-

Question 6.
Which of the following is true in case of a chemical change:

1. Identity of the substance does not change.
2. No, new substance is formed.
3. Only physical properties of the substance are changed.
4. Chemical properties of the substance are changed.

Answer:
4. Chemical properties of the substance are changed.

Question 7.
Give any one important characteristic of a chemical change?
Answer:
In this change new substance is formed.

Question 8.
Give any two examples of a physical change?
Answer:

1. Dissolution of common salt (or sugar) in water.
2. Magnetisation of an iron piece and demagnetisation of a magnet.

Question 9.
Is glowing of an electric bulb is a physical change or chemical ?
Answer:
Physical change.

Question 10.
List any two chemical changes with which we come across in our daily life.
Answer:

1. Durdling of milk, and
2. Digestion of food.

Question 11.
Classify the following into physical change and chemical change:

(a) Souring of kneaded flour
(b) Change of sugarcane juice to vinegar
(c) Evaporation of water
(d) Change of an iron rod to a magnet
(e) Pickling
(f) Dissolving common salt in water
(g) Change of cattle dung to biogas
(h) Glowing of an electric bulb.

Answer:

Physical change: (c), (d), (f), (h).
Chemical change: (a), (b), (e), (g).

Question 12.
Give one difference between physical and chemical change.
Answer:
In a physical change new substance is not formed, whereas in a chemical change new substance is formed.

Question 13.
Are the following changes physical or chemical:

1. Burning of candle
2. Preparation of soap from oil and caustic soda
3. Dissolving sugar in cone, sulphuric acid, and
4. conversion of grape juice to wine.

Answer:
Chemical change.

Question 14.
Pick up chemical changes out of the following:

(a) Souring of milk
(b) Making of ice – cream
(c) Burning of a candle
(d) Lighting of an electric bulb
(e) Respiration
(f) Heating of ammonium chloride
(g) Melting of wax.
(h) Breaking a chalk.

Answer:

Physical change: (b), (d), (f), (g), (h).
Chemical change: (a), (c), (e).

Question 15.
What are main points under which physical changes can be classified?
Answer:
The three main points viz. change in state, dispersion in solution, magnetisation and electrical changes.

Question 16.
Define rate of a chemical reaction.
Answer:
The rate of reaction is the quantity of products obtained per unit time from the reactant.

Question 17.
List a fast reaction.
Answer:
2Na + 2H₂O → 2NaOH + H₂ ↑

Question 18.
List the factors which influence the rate of a chemical reaction.
Answer:

1. Nature and state of reactants
2. Temperature
3. Concentration of the reactants
4. Catalyst.

Question 19.
What happens when temperature of a chemical reaction increases?
Answer:
Rate of reaction increases.

Physical and Chemical Changes Short Answer Type Question

Question 1.
How can you say that burning of coal and passing of electric current through water are chemical changes?
Answer:
Burning of coal:
When coal is burnt carbon dioxide gas is formed and ash is left behind as residue. Thus, new substances with new properties are formed. It is because the molecular structure of carbon-dioxide and coal are quite different from that of coal. Further more coal cannot be obtained back, hence it is a permanent change. So, it is a chemical change.

Passing of electric currnet through water:
When electric current is passed throuth water it decomposes to hydrogen and oxygen. The molecular structure of the later viz. H₂ and O₂ is different from that of H₂O, therefore the change is a chemical one.

Question 2.
Define a physical change?
Answer:
Physical change:
A physical change is a change in the physical properties (colour, state, density etc.) and does not involve a change in molecular structure. No new substance is formed and the change can be reversed by ordinary physical means.

Question 3.
Prove that evaporation of water and heating of iron to redness are physical changes?
Answer:
When water is heated, it changes into steam. No new substance has been formed because the molecular structures of water and steam are the same. Water has merely undergone a change in form (liquid → gas).

Further steam can be converted back into water just by the process of cooling therefore, this is a temporary change. Similary when iron is heated to redness, it is a temporary change in colour because on cooling iron is obtained back in its original form.

Question 4.
How can you argue that the following changes are physical changes:

1. Dissolution of sugar in water
2. Melting of wax
3. Lighting of bulb
4. Breaking of a chalk stick.

Answer:
1. Dissolution of sugar in water:
Is a physical change because no new substance is formed. On boiling off water, sugar can be obtained back.

2. Melting of wax:
When wax is heated in a dish, it melts but its composition does not change. On cooling we get back wax.

3. Lighting of bulb:
When an electric bulb is lighted by-passing electric current, the filament glows and emits light. But no new substance is formed. So it is a temporary change.

4. Breaking of a chalk stick:
When a chalk breaks, no new substance is formed. The identity of chalk aslo does not change. Therefore, it is a physical change.

Question 5.
Dispersion of a substance is a physical change or chemical one.
Answer:
Dispersion in solution:
This is also a physical change in many cases. The solute molecules get dispersed amongst the solvent molecules. They do not suffer a change in molecular structure and the solute can be recovered unchanged by cation of the solvent.

Question 6.
Give some chemical reactions which occurs in our daily life.
Answer:
Some important chemical reactions that occur in our daily life are:

1. Respiration (during respiration oxidation of glucose takes place).
2. Digestion of food.
3. Combustion of fuels.
4. Ripening of fruits.
5. Cooking of food.
6. Rusting of iron.

Question 7.
Explain that change in state is nothing but a physical change?
Answer:
Change in state:
All the substances can be transformed to gases, liquids or solids by changing temperature or the other physical conditions. In the solid state the constituent particles are ordred. In the liquid state they are less ordered; in the gaseous state they are most disordered. So, the physical state of a substance can be changed by application of energy.

Thus, changes of a solid to liquid i.e., melting of a solid, change of vapour to liquid etc. can be reversed by application of enerty i.e., either by supplying heat or by cooling. This leads to the conclusion that change of state is nothing but a physical change.

Question 8.
Why heating of a metal say platinum, to redness is a physical change?
Answer:
When platinum is heated to redness it glows. This is only due to temporary excitement of electrons in its atoms. When we stop heating in electrons get unexcited and consequently it ceases glowing. Therefore, change under consideration is definitely a physical change.

Question 9.
Explain as to why the following changes are chemical changes?

1. Rusting of iron
2. Souring of milk
3. Burning of magnesium
4. Pickling.

Answer:
1. Rusting of iron:
During the phenomenon new substances viz. iron oxide etc. are formed on the surface of iron. Iron cannot be obtained back from rust. So, rusting of iron is a chemical change.

2. Souring of milk:
As a result of souring of milk new sub¬stances are formed which cannot be converted back to milk, hence souring of milk is a chemical change.

3. Burning of magnesium:
When Mg burns new substance viz. magnesium oxide is formed, which cannot be converted back to magnesium and oxygen. Therefore burning of magnesium is a chemical change.
2Mg + O₂ → 2MgO

4. Pickling:
Pickling is nothing but the fermentation of the vegetable. Pickled vegetables cannot be changed back to fresh vegetables. Hence, it is also a chemical changed.

Question 10.
Give brief distinction between physical change and chemical change.
Answer:
Distinction between physical and chemical changes:
Physical Change:

• Change in physical properties.
• Temporary change.
• Composition of matter does not change.
• No new substance is formed.
• Can be reversed by physical means.
• Not accompanied by large energy changes.
• No change in weight.

Chemical Change:

• Change in chemical properties.
• More or less a permanent change.
• Composition of matter changes.
• New substance is formed.
• Cannot be reversed easily.
• Accompanied by large energy changes.
• Though total mass remains constant, mass of individual substance changes.

Question 11.
Is the solution of hydrogen chloride in water a physical changes?
Answer:
Hydrogen chloride is a covalent molecule. In solution it becomes electrovalent. The hydrogen ion combines with a water molecule to form hydronium ion. The properties of the solution are entirely different. There is a change in molecular structure and so as per our definition it is a chemical change.

Question 12.
Is an allotropic change a chemical change?
Answer:
The constituent atoms are identical in allotropes but allotropy is caused by change in molecular structure. Oxygen gas contains two atoms in each molecule but ozone contains three. In many cases the chemical as well as physical properties are different. So we have to conclude that allotropic change is a chemical change.

Question 13.
Is the cooking of rice a physical change?
Answer:
In cooking the fast molecules of boiling water pierce the walls of the cell in which strach is enclosed and release the starch. Sight hydrolysis also takes place. But the change is physical to a major extent since most of the starch remains unchanged.

Question 14.
What type of change is sublimation of ammonium chloride?
Answer:
Ammonium chloride on heating splits up into gases ammonia and hydrogen chloride. These gaseous products recombine on cooling to give the original salt. The apparent physical change is the result of two distinct chemical changes decomposition and combination. Sublimation can also be a physical change when the sub – stance is below its triple point and the change to vapour and back to solid state takes place directly, but in the case of ammonium chloride and many other compounds dissociation occurs.

Question 15.
Magnetisation of an iron bar is a physical change. Explain.
Answer:
Magnetisation of an iron bar:
Magnetisation caused by alignment of constituent atoms [figs, (a) and (b)] and as such it is to be considered only as a physical change. Charging and discharging of a condenser a temporary and physical change.

Physical and Chemical Changes Long Answer Type Question

Question 1.
Give in detail the distinction between physical and chemical changes?
Answer:
Distinction between physical and chemical changes:
As already stated a chemical change involves a change in the structure of the molecules while a physical change does not involve a change in molecular structure. This definition is comprehensive and all other characteristic of a chemical change can be deduced easily as floows.

1. During a chemical change new substances with new properties are produced:
Change in molecular structure means a new substance with new properties. On the other hand, a physical change does not involve a change in the molecular structure.

2. A chemical change is a permanent change and the original substance is not got back by reversing the conditions. A physical change is temporary and exist only as long as the imposed conditions exist. A physical change can be reversed by reversing the conditions.

3. No change, physical or chemical can take place without energy change. A large amount of heat energy has to be given to convert water into steam. But the energy involved in chemical changes is generally far greater than that involved in physical changes.

4. A chemical change means a physical change also, because won news substances with new properties are produced the physical state and physical properties are altered.

Question 2.
Give a detailed account of modem approach of physical and chemical changes?
Answer:
Modern approach of physical and chemical changes:
As your studies in science progress you will appreciate the point of view that all changes are chemical changes. Chemical changes are changes in structure. Minor electronic changes do occure even when a physical change takes place. In solids, subjected to heat, the ions oscillate with increasing amplitude and electrons move with greater speeds in expanded orbitals. Breaking a piece of diamond is an accepted chemical change because covalent chemical bonds are broken in the process. The same is happening when any substance is broken.

Thedivision into physical and chemical changes is, therefore, purely a matter of convenience. The three types of changes are classified as fallows:

1. Physical change:
Slight changes in outer electron states. Comparatively less energy change. No change in molecular patterns. No change in nucleonic pattern.

2. Chemical change:
Change in molecular pattern. Large scale energy change. Rearrangement, of electronic orbitals. No change in nucleonic pattern.

Question 3.
What are slow and fast reactions? Give example.
Answer:
A reaction can be called slow or fast depending upon the speed rate of reaction.
Whenever elements and compounds react their reaction is said to be slow if the rate of the reaction, i.e., the quantity of products obtained per unit time from the reactants, is slow.
Example:

1. Rusting of iron is a slow reaction.
2. When a copper vessel kept in moist air it gets greenished due to the formation of basic copper carbonate. To the contrary if the speed or the rate of the reaction is fast, than the reaction is said to be the fast reaction.

Example:
By adding sodium chloride in silver nitrate solution, immediately a white ppt. appears. It is a fast reaction i.e.,

Question 4.
What is a chemical reaction? Give an example.
Answer:
A reaction in which the following are being occurred is called a chemical reaction:

1. Absorption or liberation of heat or any other form of energy.
2. Change in the identity of the combining substances i.e., the reactants.
3. Collision among the reactant molecules.
4. Use of some catalyst or provision of some form of energy to the reactants for initiation of reaction.

Example:
1. Sodium reacts with water to form sodium hydroxide alongwith the liberation of hydrogen gas.
The chemical equation of the reaction is as follows:
2Na + 2H₂O → NaOH + H₂

2. Lime stone, on heating, liberates carbon dioxide.
The equation for the reaction is as follows:
CaCO₃ → CaO + CO₂.

MP Board Class 7th Science Solutions

MP Board Class 7th Science Solutions Chapter 18 Wastewater Story

Activities

Activity – 1
We have given one example of the use of clean water. You can add many more?

Answer:

Activity – 2
Locates an open drain near your home, school or on the roadside and inspect water flowing through it? Record color, odour and any other observation. Discuss with your friends and your teacher and fill up the following Table?
Table: Contaminant survey

Wastewater Story Text Book Exercises

Question 1.
Fill in the blanks:

1. Cleaning of water is a process of removing ……………………….
2. Waste – water released by houses is called ………………………
3. Dried ……………………… is used as manure.
4. Drains get blocked by …………………….. and ………………………..

Answer:

1. Contaminants
2. Sewage
3. Dung
4. Plastic, sludge.

Question 2.
What is sewage? Explain why it is harmful to discharge untreated sewage into rivers or seas?
Answer:
Sewage is waste – water released by homes, hospitals, offices, industries and other users. It also includes rainwater that has run down the street during a heavy rain or storm. The water that washes off roads and roof tops carries harmful substances with it. Basically sewage is a liquid waste. Most of it is water, which has dissolved and suspended impurities which are called contaminants. That is why it is harmful to discharge untreated sewage in to rivers or seas.

Question 3.
Why should oils and fats be not released in the drain? Explain.
Answer:
Oils and fats should not be released in the drains because they harden the soil in the pipes and block them. Fats get clogged in the holes of the soil in the drain and block it. It does not allow the waste – water to flow and thus the whole sewer system is blocked.

Question 4.
Describe the steps involved in getting clarified water from waste – water?
Answer:
Treatment of waste – water involves physical, chemical, and biological processes, which remove physical, chemical and biological matter that contaminates the waste – water.

1. Waste – water is passed through bar screens. Large objects like rags, sticks, cans, plastic packets, napkins are removed.

2. Water goes to a grit and sand removal tank. The speed of the incoming waste-water is decreased to allow sand, grit and pebbles to settle down.

3. The water is then allowed to settle in a large tank which is sloped towards the middle. Solids like faces settle at the bottom and are removed with a scraper. This is the sludge. A skimmer removes the float able solids like oil and grease. Water so cleared is called clarified water.

4. The sludge is transferred to a separate tank where it is decomposed by the anaerobic bacteria. The bio gas produced in the process can be used as fuel or can be used to produce electricity.

5. Air is pumped into the clarified water to help aerobic bacteria to grow. Bacteria consume human waste, food waste, soaps and other unwanted matter still remaining in clarified water. After several hours, the suspended microbes settle at the bottom of the tank as activated sludge. The water is then removed from the top.

Question 5.
What is sludge? Explain how it is treated?
Answer:
Sludge is the collected solid waste from the waste – water during the treatment in water treatment plant. Sludge is decomposed in a separate tank by the anaerobic bacteria. The activated sludge is about 97% water. The water is removed by sand drying beds or machines. Dried sludge is used as manure, returning organic matter and nutrients to the soil.

The treated water has a very low level of organic material and suspended matter. It is discharged into a sea, a river or into the ground. Nature cleans it up further. Sometimes it may be necessary to disinfect water with chemicals like chlorine and ozone before releasing it into the distribution system.

Question 6.
Untreated human excreta is a health hazard? Explain?
Answer:
Untreated human excreta is a health hazard. It may cause water pollution and soil pollution. Both the surface water and groundwater get polluted. Groundwater is a source of water for wells, tubewells, springs and many rivers. Thus, it becomes the most common route for water borne diseases. They include chlorea, typhoid, polio, meaningities, hepatitis and dysentery.

Question 7.
Name two chemicals used to disinfect water?
Answer:
Ozone, chlorine.

Question 8.
Explain the function of bar screens in a waste – water treatment plant?
Answer:
Bar screens clear the waste – water of all the physical impurities. Large waste objects like napkins, plastics, can sticks, rags etc. are removed from the waste – water through the bar screens.

Question 9.
Explain the relationship between sanitation and disease?
Answer:
Untreated human excreta is a health hazard. It may cause water pollution and soil pollution. Both the surface water and groundwater get polluted. Groundwater is a source of water for walls, tubewells, springs and many rivers. Thus, it becomes the most common route for water borne diseases. They include cholera, typhoid, polio, meningitis, hepatitis and dysentery. That is proper sanitation is must to avoid some of the deadliest diseases.

Question 10.
Outline your role as an active citizen in relation to sanitation?
Answer:
As active citizen we should take care of our personal and environmental sanitation. We should make people around us, aware of the benefits of sanitation we should help the municipal corporations and gram panchayats to cover all the open drains and remove the unhygienic and disease causing substances thrown in open.

Question 11.
Here is a crossword puzzle: Good luck!

Across

1. Liquid waste products
2. Solid waste extracted in sewage treatment
3. A word related to hygiene
4. Waste matter discharged from human body.

Down

1. Used water
2. A pipe carrying sewage.
3. Micro – organisms which causes cholera.
4. A chemical to disinfect water.

Answer:

Question 12.
Study the following statements about ozone:

1. It is essential for breathing of living organisms.
2. It is used to disinfect water.
3. It absorbs ultraviolet rays.
4. Its proportion in air is about 3%.

Which of these statements are correct?

1. (a), (b) and (c)
2. (b) and (c)
3. (a) and (d)
4. All four.

Answer:

2. (b) and (c).

Extended Learning – Activities and Projects

Question 1.
Construct a crossword puzzle of your using the keywords?
Answer:

Across:

1. Mixing with air.
2. Decomposed product of leaves.
3. Does not read oxygen
4. Needs oxygen.

Down:

1. Necessary for hygiene
2. Solid waste
3. Pipes to carry sewage

Question 2.
Then and now: Talk to your grand parents and other elderly people in the neighbourhood? Find out the sewage disposal systems available to them. You can also write letters to people living in far off places to get more information. Prepare a brief report on the information you collected?
Answer:
Do yourself.

Question 3.
Visit a sewage treatment plant?
It could be as exciting and enriching as a visit to a zoo, a museum, or a park? To guide your observation here are a few suggestions?

Record in your notepad:
Place ……………….. Date …………………… Time
Name of the official at the plant ………………………. Guide/Teacher …………………………

1. The location of the sewage plant.
2. Treatment capacity.
3. The purpose of screening as the initial process?
4. How is air bubbled through the aeration tank?
5. How safe is the water at the end of the treatment? How is it tested?
6. Where is the water discharged after treatment?
7. What happens to the plant during heavy rains?
8. Is bio gas consumed within the plant or sold to other consumers?
9. What happens to the treated sludge?
10. Is there any special effort to protect nearby houses from the plant?
11. Other observations.

Answer:
Do with the help of your subject teacher.

Wastewater Story Additional Important Questions

Objective Type Questions

Question 1.
Choose the correct alternative :

Question (a)
This is not the cause of water pollution?
(a) Floods
(b) Rains
(c) Chemicals
(d) Open defecation.
Answer:
(b) Rains

Question (b)
To improve sanitation following new technique is being used?
(a) Vermi – processing toilets
(b) Sewer system
(c) Onsite sewage disposal
(d) Both (a) and (b).
Answer:
(d) Both (a) and (b).

Question (c)
Following should not be disposed off in the drains?
(a) Tissue Papers
(b) Excreta
(c) Oils and Fats
(d) Waste water.
Answer:
(c) Oils and Fats

Question (d)
Following process is not a part of waste – water treatment?
(a) Decomposition
(b) Grit and Sand Removal
(c) Evaporation
(d) Chlorination.
Answer:
(c) Evaporation

Question (e)
Polluted water causes disease likes –
(a) Hepatitis
(b) Typhopid
(c) Cholera
(d) Diarrhoea.
Answer:
(c) Cholera

Question (f)
In a public sewerage system, the largest sewers are –
(a) Filters
(b) Interceptors
(c) Waterways
(d) None of these.
Answer:
(b) Interceptors

Question 2.
Fill in the blanks:

1. …………………… bacteria is used to treat sludge.
2. Sewage is a liquid waste which causes water and soil
3. Waste – water is treated in a sewage treatment ………………………
4. …………………… and …………………….. are the products of water clarification.
5. By – products of waste – water treatment are sludge and ………………………
6. Addition of disease causing organisms in water is called water …………………….
7. …………………………… in open cause health hazards.
8. ……………………….. is used as manure.
9. To improve sanitation, low cost ……………………….. sewage disposal systems are being encouraged.
10. Adopting good sanitation practices should be our way of ……………………………….

Answer:

1. Anaerobic
2. Pollution
3. Plant
4. Sludge and bio gas
5. Bio – gas
6. Contamination
7. Defecation
8. Activated sludge
9. Onsite
10. Life.

Question 3.
Which of the following statements are true (T) or false(F):

1. Sewage contains pure water for drinking.
2. Used water is waste – water.
3. Waste – water could not be reused.
4. Open drain system is a breeding place for flies.
5. Manholes are located at every 50 m to 60 m in the sewerage.
6. Waste – water is passed through for screens.
7. Eucalyptus trees absorb all surplus waste – water rapidly and release pure water vapour into the atmosphere.

Answer:

1. False
2. True
3. False
4. True
5. True
6. True
7. True.

Wastewater Story Very Short Answer Type Questions

Question 1.
Define sewage?
Answer:
Sewage is water that contains waste products produced by human beings. It is also called waste water.

Question 2.
Which is the world water day?
Answer:
22nd March.

Question 3.
Which is proclaimed as the International Decade for action on water for life?
Answer:
United Nations proclaimed the period 2005 – 2015 as the international Decade for action on “Water for life”.

Question 4.
What do you mean by cleaning of water?
Answer:
Cleaning of water is a process of removing pollutants before it enters a water body or is reused.

Question 5.
What is sewage treatment?
Answer:
This process of wastewater treatment is commonly known as “Sewage Treatment”.

Question 6.
In how many steps sewage treatment divided?
Answer:
The sewage treatment in most cities involve two main steps primary and secondary treatment. Some cities also require an additional step called tertiary treatment.

Question 7.
What do you mean by primary treatment?
Answer:
The primary treatment removes the heaviest solid material from sewage. This process removes about half the suspended solids and bacteria in sewage. Sometimes chlorine gas is added to kill most of the remaining bacteria.

Question 8.
What do you mean by secondary treatment?
Answer:
The secondary treatment removes from 85% to 90% of the solids and oxygen consuming wastes remaining in sewage after it has undergone primary treatment. The most common methods of secondary treatment are the activated sludge process and the trickling filtration process.

Question 9.
Why should we plant eucalyptus along sewage ponds?
Answer:
These trees absorb all surplus waste – water rapidly and release pure water vapour into the atmosphere.

Question 10.
Write certain inorganic impurities in the waste – water?
Answer:
Metals, phosphates and nitrates.

Question 11.
Name certain disease causing micro – organism?
Answer:
Bacterias, Viruses etc.

Question 12.
Which process removes the solids like faces and other substances from the waste – water?
Answer:
Grit and sand removal tank.

Question 13.
How is sand, grit on pebbles settled down?
Answer:
Water goes to a grit and sand removal tank. The speed of the incoming waste-water is decreased to allow sand, grit and pebbles to settle down.

Question 14.
How is dry sludge used?
Answer:
Dried sludge is used as manure, returning organic matter and nutrients to the soil.

Question 15.
Who decomposes the sludge?
Answer:
Anaerobic bacteria decompose the sludge.

Question 16.
Which instrument is used to remove floatable solids from the waste – water?
Answer:
A skimmer is used to remove floatable impurities.

Question 17.
What helps to clean the clarified water?
Answer:
Aerobic bacteria helps to clean the clarified water.

Question 18.
Why is ozone and chlorine used?
Answer:
Ozone and chlorine is used to kill the bacteria etc. present in the clarified water.

Question 19.
Why is air pumped to clarified water?
Answer:
Air is pumped into the clarified water to help aerobic bacteria to grow. Bacteria consume human waste, food waste, soaps and other unwanted matter still remaining in clarified water.

Wastewater Story Short Answer Type Questions

Question 1.
Explain sewage?
Answer:
Waste water including human excreta which flows from our homes into the drains is called domestic sewage. This contains microbes which cause water – borne diseases. This waste water is often dumped into water bodies.

Question 2.
How is water polluted?
Answer:
Water is used various purposes in homes, industries and agriculture. When water is used for cleaning, bathing, washing, dying etc. it pollutes the water. Unwanted waste materials and chemicals etc get added in the water and this wastes the water.

Question 3.
What is done to improve sanitation?
Answer:
To improve sanitation, low cost onsite sewage disposal stem are being encouraged. Examples are septic tanks, chemical toilets, composting pits. Septic tanks are suitable for places where there is no sewerage system, for hospitals isolated buildings or a Luster of 4 to 5 houses.

Question 4.
What is vermi process toilet?
Answer:
A design of a toilet in which humans excreta is treated by earthworms has been tested in India. It has been found to be a novel, j low water – use toilet for safe processing of human waste. The operation of the toilet is very simple and hygienic. The human excreta is completely converted to vermi cakes resource much needed for soil.

Wastewater Story Long Answer Type Questions

Question 1.
How defection in open cause health hazards?
Answer:
Due to lack of proper sewage disposal system a large amount of people in India defecates in open. They use riverbeds, railway lines, fields and drains for this purpose. These excreta dries down and percolate in soil with rain water. It pollutes the ground water.

Excreate along river bed pollutes the river water. In this way water on the ground and under the ground get polluted. This polluted water contains the micro – organisms of various communicable diseases like cholera, typhoid, hepatitis and meaning it is dysentery etc.

Question 2.
Suggest some better house keeping practices?
Answer:

1. Cooking oil and fats should not be thrown down the drain. They can harden and block the pipes. In an open drain the fats dog the soil pores redunt. Its effectiveness in filtering water. Oil and fats should he thrown in the dustbin.

2. Chemicals like paints, vents, insecticides, motor oil, medicines may kill microbes it help purity water. So they should not be thrown in the drain.

3. Used ten – leaves, solid food remains, soft toys, cotton, sanitary towels, etc. should also be thrown in the dustbin. These waste choke the drains. They do not allow free flow of oxygen. This hampers the degradation process.

Question 3.
What is the composition of sewage?
Answer:
Sewage is a complex mixture containing suspended solids, organic and inorganic impurities. nutrients, saprotrophic and disease causing bacteria and other microbes.

1. Organic impurities:
Human faces, animal waste, oil, urea (urine), pesticides, herbicides, fruit and vegetable waste, etc.

2. Inorganic impurities:
Nitrates, phosphates, metals. Nutrients Phosphorus and nitrogen.

3. Bacteria:
Such as which cause cholera and typhoid.

4. Other microbes:
Such as which cause dysentery.

Question 4.
How is sewage treated?
Answer:
Domestic sewage should be treated before being discharged into the river. Sewage is treated by first separating the solid material by sedimentation and filtration. Compressed air is then passed through the liquid which is then chlorinated to kill micro – organisms. The solid matter separated from sewage can be used to generated bio gas which can be used as fuel. The sludge that is left can be used as manure in the fields to grow organic foods.

Question 5.
What are the different ways in which solid waste can be disposed off?
Answer:
The different ways are as:

1. Domestic wastes like fruit and vegetable waste, leftover food, leaves of potted plants can be converted into compost and used as manure.
2. Most of the solid waste is buried in low lying areas to level uneven land. This is called landfill.
3. Wastes coming from industries such as metals can be recycled and used again.
4. Broken plastic articles like plastic bags, buckets, bowls, cups, plates, etc. can be melted and remolded to make new articles.
5. The waste disposal on a large scale is done by the municipality of a city using incinerators. The solid waste is burnt at high temperature. Ash is removed from time to time.

Question 6.
Explain sewage treatment plant.
Answer:
Sewage is water that contains waste products by human beings. It is also known as waste water. In fact sewage comes from the sinks and toilets of homes, restaurants, factories and office buildings. The sewage mainly consists of dissolved material that cannot be seen and bits of such solid matter as human waste and ground up rubbish.

It also contains harmful chemical and disease producting bacteria. Most sewage ultimately goes into lakes, rivers and oceans. However, in many western nations, the sewage is treated in some way before it goes into the waterways as a semi – clear liquid called effluent. Most methods used to treat sewage convert organic sewage into inorganic compounds viz. nitratres, sulphates and phosphates. Some of these compounds serve as food for algae. As the algae decay using excess of oxygen from water, the fish and plants in water will ultimately die.

Question 7.
Explain rural sewerage system?
Answer:
Many rural areas not served by public sewers. In such areas, most home owners use septic tanks to treat their sewage. These tanks are concrete or steel containers buried underground at home and buildings. Sewage flows into a septic tank through a pipe connecting the tank with a building.

Solids in the sewage sink to the bottom of the tank as sludge or float to the surface as scum. Effluent then flows from the tank into a system of pipes with open joints that allow sewage effluent to be gradually distributed into the soil. The soil bacteria then destroy the remaining organic material in the influent.

In a septic tank, bacteria in the sewage attack and digest the sludge and scum. The digestion process changes most to the wastes into gas and a harmless substance called humus. The gas then escapes into the air. The humus in the tank should be pumped our periodically and taken to a sewage treatment plant.

Question 8.
Explaining urban sewerage system?
Answer:
In a public sewerage system, the largest sewers, known as interceptors, carry the sewage to a wastewater treatment plant. The sewage treatment in most cities involves two main steps, primary treatment and secondary treatment. Some cities also require an additional step called tertiary treatment. At a treatment plant, sewage first passes through a screen that traps the largest pieces of matter. It then flows through a grit chamber, where heavy inorganic matter, such as sand, settles down.

The liquid next flows into a large primary sedimentations tank. Many suspended solids sink to the bottom of this tank and form a muddy material called sludge. Grease floats to the surface, where it is removed by a process called skimming. The effluent is then released into waterways.

Primary treatment removes bout half of the suspended solids and bacteria in sewage. Sometimes chlorine gas is added after primary or secondary treatment to kill most of the remaining bacteria. The secondary treatment removes about 85 to 90 percent of the solids and oxygen consuming wastes remaining in sewage after it has undergone primary treatment.

Question 9.
Explain the most common methods of secondary treatment in urban sewerage system?
Answer:
The most common methods of secondary treatment are:

1. The activated sludge process.
2. The trickling filtration process.

In case of activated sludge process, the influent from the primary sedimentation tank flows into a second tank called an aeration tank. The useful bacteria move through the liquid and change the organic matter into less harmful substances. The liquid then flows into a final sedimentation tank, where the sludge settles down to the bottom.

The influent is then discharged into waterways. In case of trickling filtration process, the filters are filled with crushed rocks. As sewage is distributed over the rocks, it reacts with slime that develops on the rocks. The slime contains useful bacteria that change organic material in the sewage into less harmful substances. These substances are removed in a final sedimentation tank, where they fall to the bottom as sludge.

Sometimes tertiary treatment is also used after primary and secondary treatment to produce purer effluent. The tertiary treatment methods include chemical treatment, microscopic screening, radiation treatment, etc. Tertiary treatment makes effluent safer to discharge into waterways.

MP Board Class 7th Science Solutions

MP Board Class 7th Science Solutions Chapter 5 Acids, Bases and Salts

Acids, Bases and Salts Intext Questions

Question 1.
Can I taste all substances to find their taste?
Answer:
No, we should not taste unknown substances. They could harm us.

Question 2.
I am not getting the same result when using solid baking soda on dry litmus paper. Why?
Answer:
Make a solution of baking soda and then try.

Activities
Activity 1
Let us recall tastes of some edible substances listed in table. If you have not tasted any of these substances taste it now and enter the result in the given table.
Answer:

Activity 2
Mix some water with lemon juice in a plastic cup/ tumbler/ test tube. Put a drop of the above solution on a strip of the red litmus paper with the help of a dropper.

• Is there any change in colour.
• Repeat the same exercise with the blue litmus paper.
• Note down if there is any change in colour.

Perform the same activity with the following substances:
Tap water, detergent solution, aerated drink, soap solution, shampoo, common salt solution, sugar solution, vinegar, baking soda solution, milk of magnesia, washing soda solution, lime water. If possible make solutions in distilled water. Record your observations as in table.
Answer:

Activity 3
Take a tablespoonful of turmeric powder. Add a little water and make a paste.
Make turmeric paper by depositing turmeric paste on blotting paper/filter paper and drying it. Cut thin strips of the yellow paper obtained.

• Put a drop of soap solution on the strip of turmeric paper.
• What do you observe
• Similarly test the solutions listed in table and note down your observations.

Answer:
The turmeric turns red.

Acitivity 4
Collect some China rose (Gudhal) petals and place them in a beaker. Add some warm water. Keep the mixture for some time till water becomes coloured. Use the coloured water as an indicator. Add five drops of the indicator to each of the solutions given in table:

Acids, Bases and Salts Text book Exercises

Question 1.
State ditterences between acids and bases?
Answer:
Differences between acids and bases:
Acids:

1. Acids are substances which contain one or more replaceable hydrogen atoms.
2. All acids are sour in taste.
3. All acids turn blue litmus red.
4. Acids are compounds that contain hydrogen.
5. Acids react with metal to form salts and release hydrogen gas.

Bases:

1. Bases are substances which have one or more replaceable hydroxyl group (OH).
2. Bases are bitter in taste and slippry in touch.
3. Bases turn red litmus blue.
4. Bases are compound which have hydroxyl group.
5. Bases react with acids to form salts.

Question 2.
Ammonia is found in many household products, such as window cleaners. It turns red litmus blue. What is its nature?
Answer:
Basic.

Question 3.
Name the source from which litmus solution is obtained. What is the use of this solution?
Answer:
Litmus solution is extracted from lichens. It is used as indicator.

Question 4.
Is the distilled water acidic/basic/neutral? How would you verify it?
Answer:
The distilled water is neutral.

Put a drop of distilled water on a strip of the red litmus paper with the help of a droper. We observe that colour of the litmus paper is not change. The solutions which do not change the colour of either red or blue litmus are knwon as neutral solutions. These substances are neither acidic nor basic.

Question 5.
Describe the process of neutralisation with the help of an example?
Answer:
The reaction between an acid and a base is known as neutralisation. Salt and water are produced in this process with the evolution of heat.
Acid + Base → Salt + Water
Example: Following reaction:
Hydrochloric acid (HCl) + Sodium hydroxide (NaOH) → Sodium chloride (NaCl) + Water (H₂O)

Question 6.
Mark ‘T’ if the statement is true and ‘F’ if it is false:

1. Nitric acid turn red litmus blue. (T/F)
2. Sodium hydroxide turns blue litmus red. (T/F)
3. Sodium hydroxide and hydrochloric acid neutralise each other and form salt and water. (T/F)
4. Indicator is a substance which shows different colours in acidic and basic solutions. (T/F)
5. Tooth decay is caused by the presence of a base. (T/F)

Answer:

1. False (F)
2. False (F)
3. True (T)
4. True (T)
5. False (F).

Question 7.
Dorji has a few bottles of soft drink in his restaurant. But, unfortunately, these are not labelled. He has to serve tire drinks on the demand of customers. One customer wants acidic drind, another wants basic and third one wants neutral drink. How will Dorji decide which drink is to be served to whom?
Answer:

1. He can decide by the use of indicator.
2. It the sample of drink turns red litmus blue, it is basic. It it turns blue litmus red, it is acidic.
3. It it does not effect litmus, then it is neutral.

Question 8.
Explain why?

1. An antacid tablet is taken when you suffer from acidity.
2. Calamine solution is applied on the skin when an ant bites.
3. Factory waste is neutralised before disposing it into the water bodies.

Answer:
1. Our stomach contains hydrachloric acid. It help us to digest food. But too mcuh of acid in the stomach causes indigestion. Sometimes indigestion is painful. To relieve indigestion, we take an antacid such as milk of magnesia, which contains magnesium hydroxide. It neutralises the effect of excessive acid.

2. Ant injects an acid (i.e., formic acid) during bite which cavses the burning sensation. Calamine solution is basic in nature. It neutralises the acid and relives us from the pain.

3. Factory wastes contain both acidic and basic substances. If they are allowed to flaw into the water bodies, they are harmful for orgainsms living in water. So the factory wastes are neutralised by adding basic substances.

Question 9.
Three liquids are given to you. One is hydrochloric acid, another is sodium hydroxide and third is a sugar solution. How will you identify them? You have only turmeric indicator.
Answer:
Turmeric solution turns red in contact with bases. It is not affected by acids and neutral substances. So, first we will identify the base.

Now, the base is taken and turmeric is added. It will turn red. Then, one of the solutions is added to it gradually. If the solution turns yellow again, the added liquid is hydrochloric acid because it neutralises the base. Otherwise the added liquid is sugar solution.

Question 10.
Blue litmus paper is dipped in a solution. It remains blue. What is the nature of the solution? Explain.
Answer:
The nature of the solution is neutral, because the solutions which do not change the colour of either red or blue litmus are known as neutral solution. These substances are neither acidic nor basic.

Question 11.
Consider the following statements:

1. Both acids and bases changes colour of all indicators.
2. If an indicator gives a colour change with an acid, it does give a change with a base.
3. If an indicator changes colour with a base, it does not change colour with an acid.
4. Change of colour in an acid and a base depends on the type of the indicator.

Which of these statements are correct?

1. All four
2. (a) and (d)
3. (b) and (c)
4. only (d)

Answer:
4. only (d).

Extended Learning – Activities and Projects:

Question 1.
Using the knowledge of acids and bases, write a secret message with the help of baking soda and beet root. Explain how it works?
Answer:
Prepare baking soda solution in water. Use this solution to write the message on a sheet of white paper with a cotton bud. Rub a slice of fresh beet root over the message.

Question 2.
Prepare red cabbage juice by boiling a piece of red cabbage in water. Use it as an indicator and test the acidic and basic solutions with it. Present your observations in the form of a table?
Answer:
Do with the help of your subject teacher.

Question 3.
Bring the soil sample of your area, find out if it is acidic, basic or neutral. Discuss with farmers if they treat the soil in any manner?
Answer:
Do yourself.

Question 4.
Visit a doctor. Find out the medicines, he prescribes to treat acidity Ask him how acidity can be prevented?
Answer:
Do yourself.

Acids, Bases and Salts Additional Important Questions

Objective Type Questions

Question 1
Choose the correct alternative

Question (i)
Bases are –
(a) Sour in taste
(b) Sweet in taste
(c) Bitter in taste
(d) None of the above.
Answer:
(c) Bitter in taste

Question (ii)
Blue litmus turns red by –
(a) Sodium
(b) Sodiujn sulphate
(c) Bitter in taste
(d) Qattstic potash.
Answer:
(c) Bitter in taste

Question (iii)
Which one of the following oxides will react with acids to salt and water –
(a) CO
(b) SO₂
(c) SO₃
(d) CuO.
Answer:
(d) CuO.

Question (iv)
Which of the following is a mineral acid –
(a) Acetic acid
(b) Citric acid
(c) Tartaric acid
(d) Nitric acid.
Answer:
(d) Nitric acid.

Question (v)
Which is the common name of sodium bicarbonate –
(a) Caustic soda
(b) Washing soda
(c) Blue vitriol
(d) Baking soda.
Answer:
(d) Baking soda.

Question (vi)
For diluting acid –
(a) Water is added to acid.
(b) Acid is added to water.
(c) Acid is boiled after adding water.
(d) Acid is boiled before adding water.
Answer:
(c) Acid is boiled after adding water.

Question (vii)
……………. is used for white – washing in house.
(a) Sodium hydroxide
(b) lime stone, calcium hydroxide
(c) blue vitriol
(d) lime water and ash.
Answer:
(b) lime stone, calcium hydroxide

Question (viii)
Nausadar is –
(a) Acid
(b) Alkali
(c) Salt
(d) Indicatior
Answer:
(c) Salt

Fill in the blanks:

1. Acetic acid is present in while is present ………….. While …………. is present in lemon.
2. Magnesium burns in air to form …………. which is ………….. oxide.
3. The chemical formula of slaked lime is ……………..
4. Acids are …………….. in taste.
5. The gas which escapes out from many aerated soft drinks is …………..
6. ………….. are slippery in touch.
7. Bases turn ………….. litmus to …………..
8. In a neutralisation reaction an ………….. and an ………….. combine to form a salt and water.
9. The solution formed by reacting P₂ O₅ with H₂O turns ………….. litmus ……………
10. Methyl orange is a good ……………

Answer:

1. Vinegar, citric acid
2. Magnesium oxide, basic
3. Ca₂, (OH)₂
4. Sour
5. CO₂
6. Bases
7. Red, blue
8. Acid, alkali
9. Blue, red
10. Indicator.

Question 3.
Which of the following statements are true (T) or false (F):

1. Acids have a bitter taste.
2. Bases have a bitter taste.
3. Bases react with carbonate to liberate carbon dioxide.
4. Copper does not reach with tamarind (imli) water.
5. Sulphuric acid is c.’led ‘King of chemicals’.
6. Orange juice turns blue litmus red.
7. Alum (Phitkari) acts as a antacid.
8. Soaps are salts of fatty acids.
9. Copper sulphate is used as a preservative in pickels. Potassium chloride is a salt of sulphuric acid.

Answer:

1. False
2. True
3. False
4. True
5. True
6. True
7. False
8. True
9. False
10. False.

Question 4.
Paheli brought the following paheli (riddle) for you.

1. Coffee is brown
2. And bitter in taste
3. Is it an acid
4. Or a base
5. Don’t give the answer
6. Without any test
7. You are in the dark With its taste

Answer:
Acidic.

Acids, Bases and Salts Very Short Answer Type Questions

Question 1.
Which acid is present in our stomach?
Answer:
Hydrochloric acid in small amount is present in our stomach.

Question 2.
What will you do if some acid is split on the table?
Answer:
We will sprinkle some base on the table to neutralise the effect of the acid.

Question 3.
Why antacids tablests are used to reduce acidity of the stomach?
Answer:
Sometimes due to spicy food the concentration of hydrochloric acid increases in the stomach. This causes acidity. To reduce it some harmless bases are used like milk of magnesia [Mg (OH)₂] and aluminium hydroxide, which balance the excess of acids. These are solid in the form of tablets called antacids.

Question 4.
What are mineral acids? Give two examples.
Answer:
The acids which are capable of forming hydrogen ions, when dissolved in water are mineral acids. For example, HCl, HNO₃, H₂SO₄ (Hydrochloric acid, Nitric acid, Sulphuric acid). In other words, mineral acids are strong acids. These acids are called mineral acids because these are prepared from minerals.

Question 5.
What are organic acids? Give two Examples.
Answer:
Organic acid are soured milk, lemon, green mangoes and karvanda are sour tasting. All of them contain some naturally occurring acids. Such acids are found in animals and plant materials. They are known as organic acids.
Examples: Lactic acid, Citric acid, Vinegar, Formic acid.

Question 6.
What do you understand by concentrated and dilute acids?
Answer:
Concentrated acid:
The acids which are prepared by dissolving in water, are known as concentrated acid.

Dilute acid:
The acid which are prepared by dissolving in excess amount of water are known as dilute acids.

Question 7.
Name the gas obtained when a metal carbonate reacts with an acid?
Answer:
When metal carbonate reacts with acids they give carbon dioxide gas.

Question 8.
What will happen if blue litmus paper is soaked in orange juice?
Answer:
It change into red colour.

Question 9.
State one characteristic property of all acids. Is dry hydrogen chloride gas an acid?
Answer:

1. Acids have a sour taste.
2. Acids turn blue litmus red.
3. Acids react with metal to evolve hydrogen gas.
   2HCl + Mg → MgCl₂ + H₂
   Yes, hydrogen chloride is an acid.

Question 10.
A solution turns red litmus paper into blue. What does this indicate about the chemical nature of the solution?
Answer:
The solution which turns red litmus paper blue is basic in nature. The substance which turns red litmus paper blue is known as alkalies.

Question 11.
Classify the following chemicals in acids and bases:
KON, HNO₃, Ca(OH)₂, LiOH, CH₃COOH, HCOOH, Mg(OH)₂, NaOH, H₂SO₄, HCl
Answer:
Acids:
HNO₃, H₂SO₄, HCl.

Bases:
KOH, Ca(OH)₂, LiOH, CH3COOH, HCOOH, Mg(OH)₂, NaOH.

Acids, Bases and Salts Short Answer Type Questions

Question 1.
You are given hydrochloric acid solution, sodium hydroxide solution and water in three different bottles. How will you check which bottle has which compound?
Answer:
Take three pieces of blue litmus paper. Put one piece of blue litmus paper into each of these solutions. That bottle which turns blue litmus red contains hydrochloric acid. Take three pieces of red litmus paper. Put one piece of red litmus paper into each of these solutions. That bottle which turns red litmus blue contains sodium hydroxide (base).

Question 2.
How can you test the presence of acid in a substance?
Answer:
Acids can be tested in any substance by the following methods:

1. Take a drop of the dilute solution of the substance on the tips of your tongue. If it taste sour, it is acid.
2. Place a blue litmus paper in the solution. If the colour changes to red, acid is present.

Example: 2Na + 2HCl → 2NaCl + H₂

Question 3.
What are indicators? Name two acid – base indicators.
Answer:
The substance which are used to identify whether a substance is an acid or base is called indicators. For example, litmus solutions give red colour with acids and blue colour with bases. Therefore, litmus is used as indicator. Substances wrhich given differnet colours with acid and base are called acid – base indicators.
Example:

1. Methyl orange
2. Phenolpthalein

Question 4.
State the colour of dry litmus paper when placed in separate samples of dilute sulphuric acid, moist ammonia gas, moist chlorine, sodium hydroxide, lemon juice, vinegar and water into which sulphur dioxide gas has been bubbled for some time?
Answer:

Question 5.
Why are acids not stored in metal containers? Containers/ vessels made from which material are safe to store acids?
Answer:
All the acids react with metals. They react vigorously and slowly with metals according to their nature. So, the acids are not stored in metal containers. Vessels made from glass or cermics are considered safe for strong acids.

Question 6.
Which acids are present in following substance:

Answer:

1. Citric acid
2. Acetic acid
3. Lactic acid
4. Oxalic acid
5. Tartaric acid.

Question 7.
Why does colour of blue vitriol change when heated?
Answer:
When we blue vitriol heated it changes into white vitriol and water.

Question 8.
Write one use of each of the following compounds?

1. Vinegar
2. Methly orange
3. Alum
4. Sulphuric, acid
5. Sodium hydroxide.

Answer:

1. In pickles and jam for preserving it in good condition for long duration.
2. As a indicator.
3. In purifying water.
4. In purifying pertroliujn products.
5. In purifying pertrolium products.

Question 9.
What are acid salts? Give two examples?
Answer:
Acid salt:
When a strong acid is neutralised by a weak base, then a salt is formed, such type of salt is called acid salt.
For example:
H₂SO₄ + 2NH₄OH → (NH ) SO₄ + 2H₂O
HCl+ NH₄OH → NH₄Cl + H₂O

Question 10.
Complete the following equations:

1. NaOH + H₂SO₄ → ……………. + H₂O
2. H₂CO₃ + NaOH → ……………. + H₂O
3. HNO₃ + KOH → ……………. + H₂O
4. Mg (OH)₂ + 2HCl → ……………. + 2H₂O

Answer:

1. NaOH + H₂SO₄ → Na₂SO₄ + H₂O
2. H₂CO₃ + 2NaOH → Na₂CO₃ + 2H₂O
3. HNO₃ + KOH → KNO₃+ H₂O
4. Mg (OH)₂ + 2HCl → + MgCl₂ + 2H₂O

Question 11.
Name the gas obtaines when a metal carbonate reacts with an acid?
Answer:
When metal carbonate reacts with acids they give carbon dioxide gas.
For example.

Question 12.
Differentiate between bases and alkalies by giving suitable examples of each?
Answer:
Bases:
Bases are the compound which have one or more hydroxyl group (OH) in their molecule.
Examples: NaOH, Ca(OH)₂, KOH etc.

Alkalies:
Water soluble bases are called alkalies.
Examples: Sodium hydroxide, potassium hydroxide and calcium hydroxide.

Question 13.
What is a neutralisation reaction? Give two examples.
Answer:
The reaction of an acid with an alkali and vice – versa to form salt and water is called neutralisation reaction.
For examples:

Question 14.
How is salt obtained from sea – water?
Answer:
The seas are great sources of salts. A litre of a water contains about 35 grams of salts. Sodium chloride is the main salt. The sea water is trapped in shallow called lagoons and is allowed to evaporate in sunlight to white solid crystal of salts. These crystals are processed and packed to send to markets.

Question 15.
What are the uses of weak alkalies?
Answer:

1. Ammonia is a weak alkali. It is used for the manufacture of fertilizers.
2. Ammonia is also used for the production of wood pulp and organic chemicals.
3. It is also used for making synthetic fibres such as nylon and nitric acid, which are used for the preparation of synthetic cloth.
4. Calcium hydroxide is used in the manufacture of bleaching powder.

Question 16.
Tabulate the some hydrated salts with their chemical formulae and colour?
Answer:
Some hydrated salts:

Question 17.
Name some common acid and alkali indicators?
Answer:

Acids, Bases and Salts Long Answer Type Question

Question 1.
What are acids? Write their properties.
Answer:
Acids are substances which contain one or more replaceable hydrogen atoms. Its properties are:

1. 1. All acids are sour in taste.
   2. All acids turn blue litmus red.
   3. Acids are compounds that contain hydrogen e.g., H₂SO₄, HCl etc.
   4. Acids are compounds which form hydronium ion (H₃O⁺) in aqueous (water) solution.
      Example:
      

1. Acids react with metal to form salts and release hydrogen gas.
   Example: 2Na + 2 HC1 → 2NaCl + H₂
   
2. Acids react with carbonates and bicarbonates to give carbon dioxide gas.
   Example:
   

Question 2.
What are bases? Write down its properties.
Answer:
Bases are substances which have one or more replaceable hydroxyl group (OH).
The various properties of bases are:

1. Bases are bitter in taste and slippery in touch.
2. Bases turn red litmus blue.
3. Bases are compound which have hydroxyl group.
4. All bases give hydroxyl ion into aqueous solutions.
   
5. Bases react with acids to form salts.
   Example: NaOH + HCl → NaCl + H₂O

Question 3.
What are the uses of mineral acids in industry?
Answer:
The uses of mineral acids in industry are:

1. Concentrated sulphuric acid, nitric acid and hydrochloric acid are used in a large number of metallurgical operations, manufacture of fertilizers and preparations of large number of industrial chemicals.

2. Hydrochloric acid is used for removing the deposits from inside the boilers. This process is known as descaling.

3. One of the mineral acid, hydrochloric acid (HCl) present in our stomach helps in digestion of food.

4. Nitric acid (HNO₃) is used by goldsmiths for cleaning gold and silver ornaments.

Question 4.
Distinguish clearly between the following terms by giving suitable examples:

1. Organic acid and mineral acid.
2. Base and alkali.

Answer:
1. Organic acid:

• Organic acid contains COOH functional group.
• These acids are weak.
• These acids are present in humans and plants.
• They are less corrosive and are used in food ingradients.
  Examples: Ethanoic acid, lactic acid, citric acid.

Mineral acid:

• Mineral acid contains hydrogen ions (H⁺).
• These acids are strong.
• These acids are prepared by mankind.
• They are corrosive in nature and have industrial use.
  Examples: Hydrochloric acid, sulphuric acid, nitric acid.

2. Base:

• Bases are the compound which have one or more hydroxhyl group (OH) in their molecule.
• All alkalies are bases
• Bases are insoluble in water.
  Examples: NaOH, Ca(OH)₂, KOH

Alkali:

• Water soluble bases are called alkalies.
• All bases are not alkalies.
• Alkalies are soluble in water.
  Examples: Sodium hydroxide potassium hydroxide and calcium hydroxide.

Question 5.
Write any three most common salts used in daily life and write their uses?
Answer:
Most common salts used in daily life are:
1. Washing Soda: Na₂CO₃.10H₂O.
Uses:

• It is used in laundary.
• It is used to prepare other compounds such as glass, caustic soda and detergent poweders.

2. Baking Soda: NaHCO₃
Uses:

• It is used in baking powder.
• It is used as medicine to reduce acidity of the stomach.
• It is used in fire extinguisher.

3. Potash alum or phitkari:
K₂SO_4.Al₂(SO₄)₃24H₂O
Uses:

• It is used to purify water.
• It is used after shave to stop the bleeding from cuts.

MP Board Class 7th Science Solutions