Class 8

You can Download खूबसूरत अनुभूति है एवरेस्ट! Questions and Answers, Summary, Activity, Notes, Kerala Syllabus 8th Standard Hindi Solutions Unit 5 Chapter 2 help you to revise complete Syllabus and score more marks in your examinations.

Kerala State Syllabus 8th Standard Hindi Solutions Unit 5 Chapter 2 खूबसूरत अनुभूति है एवरेस्ट!

खूबसूरत अनुभूति है एवरेस्ट! पाठ्यपुस्तक के प्रश्न और उत्तर

Kerala Syllabus 8th Standard Hindi Notes प्रश्ना 1.
जिंदगी में जिज्ञासा की क्या अहमियत है?

उत्तर:
जिज्ञासा हमें जीवन में कुछ नए करने की प्रेरणा देती है। जिज्ञासे के कारण हम कुछ लक्ष्य निश्चित करते हैं। इस लक्ष्य तक पहुँचने की कोशिश निरंतर करते रहते हैं। इसलिए जीवन में जिज्ञासा का बड़ा स्थान है।

8th Standard Hindi Notes State Syllabus प्रश्ना 2.
संतुलित दिमाग और संयम अच्छे इंसान के लिए ज़रूरी है।’ इस प्रस्ताव पर आपकी राय क्या है?

उत्तर:
संतुलित दिमाग और संयम मानव के लिए ज़रूरी है। संतुलित दिमागवाले ही क्षमा के साथ जी सकते हैं। अगर दिमाग का संतुलन बिगड़ जाता है तो वह कभी क्रुद्ध होता है या उदास होता है। सभी परिस्थितयों में संयम रखना ज़रूरी है। संयम से काम करने से जीवन में सफलता पा सकते है।

Kerala Syllabus 8th Standard Notes Hindi प्रश्ना 3.
समाज को खुश देखने की कल्पना के पीछे संतोष यादव के चरित्र की कौन सी विशेषता प्रकट होती है?

उत्तर:
समाज के प्रति सकारात्मक भाव रखना अच्छी बात है। समाज कल्याण की भावना से युक्त नागरिक ही ऐसा कर सकते हैं। इस कल्पना के पीछे संतोष यादव की समाज कल्याण की भावना हम देख सकते हैं।

खूबसूरत अनुभूति है एवरेस्ट! Textbook Activities

Hindi Class 8 Kerala Syllabus प्रश्ना 4.
संतोष यादव दो बार माउंट एवरेस्ट की चोटी पर पहुँचनेवाली भारत की पहली महिला है। दूसरी बार उनके एवरेस्ट जीतने के संबंध में एक रपट तैयार करें।


उत्तर:
संतोष यादव : दुनिया की चोटी पर… दुबारा
7 मई 1993, दिल्ली : 24 साल की उम्र में, संतोष यादव ने इंडो-तिब्बतन सीमा पुलिस के दारोगा के पद से इस्तीफ़ा दे दिया, इसी कारण से वह माउंट की। एवरस्ट चढ़ सकी। दो साल के अंदर, संतोष यादव, पद्मश्री विजेता दुनिया की चोटी को मापनेवाली दुनिया की प्रथम महिला बनी- दो बार। “एक महिला की हैसियत से मैं थोड़ा कुछ अलग करना चाहती थी, इसलिए इस्तीफ़ा देकर माउंट एवरेस्ट चढ़ने का निश्चय किया” संतोष यादव का सिद्धांत सरल है। संतोष यादव का सपना 12 मई 1992 को पहली बार साकार हुआ। संतोष यादव इससे तृप्त नहीं थी। एक साल के बाद उन्होंने दुबारा कोशिश की। 12 मई 1993 को, पहली चढ़ाई के ठीक एक साल बाद संतोष यादव दो बार माउंट एवरेस्ट को जीतनेवाली दुनिया की दुनिया की प्रथम महिला बनी। “वहाँ चोटी पर पहुँचने के लिए 14 मार्ग हैं। हम ने ऐसा रास्ता अपनाया, जो पहले किसीने अपनाया नहीं था”-संतोष यादव कहती है। उनके मत में जिंदगी चोटियों को पार करने की निरंतर कड़ियाँ हैं। यही उस जैसी महिला को चोटियों पर पहुँचाई हैं।

खूबसूरत अनुभूति है एवरेस्ट! Summary in Malayalam and Translation

खूबसूरत अनुभूति है एवरेस्ट! शब्दार्थ Word meanings

You can Download Static Electricity Questions and Answers, Summary, Activity, Notes, Kerala Syllabus 8th Standard Basic Science Solutions Chapter 20 help you to revise complete Syllabus and score more marks in your examinations.

Kerala State Syllabus 8th Standard Basic Science Solutions Chapter 20 Static Electricity

When some substances are rubbed against each other they can attract other objects. When the substances are rubbed the electrons are exchanged. An atom of a substance gets positive charge on losing electron and negative charge on receiving electron.

Proton, neutron, and electron are the subatomic particles in an atom. Neutron does not possess any charge. Proton have positive charge and electron have negative charge. In any atoms, the number of elect¬ron and proton are equal. So an atom is electrically neutral.

Electrification or charging is the process of converting an object in to electrically charge One. If the electric charge produced in an object remains at the same place in it, it is called static electricity. When a glass rod is rubbed on silk, electrons are lost from the glass rod. Then the glass rod gets positive and silk gets negative charged.

When an ebonite rod is rubbed with wool, ebonite rod gets negative and wool gets positive charged. The metals also charged when rubbed but the charge will spread overall part of the metallic substance. This causes current electricity, there is no static electricity in metals.

Static Electricity Class 8 Kerala Syllabus Properties of electric charges

• Charged bodies attract uncharged bodies.
• Unlike charges attracts each other
• Like charges repel each other As the charged bodies attract uncharged bodies if two bodies attract each other we cannot say certainly both the bodies possess charge. But if two bodies repel each other it is sure that both bodies possess like charge.

The unit of charge is coulomb. Charge is a scalar quantity. The electroscope is the instrument to know the presence of static electric charge. It is an instrument in which a metallic conductor, gold leaves and a metal ball are connected in a glass jar.

The activity to neutralize the charge on a body is known as discharging.

Static Electricity Class 8 Notes Pdf Kerala Syllabus Earthing

Connecting a body to the earth using metallic conductor is known as earthing. On earthing a charged body, electrons pass from the earth to the body or from the body to the earth to neutralize the charge on the body completely. The give or receives electrons at any time and any quantity. So earth is referred to as an electron bank. If a positively charged body is earthed the electrons flow from earth to the body and if it is charged negatively, the electrons flow to the earth.

Static Electricity Class 8 Notes Kerala Syllabus Electrostatic induction

On bringing a charged body near to an object the charge is induced to that body. The redistribution of charges in a body as a result of the presence of another charged body is called electrostatic induction. Due to the presence of charged body, the opposite charge is induced on the other body. Then they are attracted each other. If the bodies are in contact due to attraction the opposite charges are canceled.

Chapter 20 Static Electricity Answers Kerala Syllabus Capacitor

When a metallic plate is placed near another plate which is positively charged, there is an electric field is formed between them. With this arrangement, electric charge can be stored and retained for a long time. The device which can store electric charge in this way is a called a capacitor. The charge is distributed in a conductor would be only on its surface. The amount of charge would be more at the pointed ends.

Class 8 Physics Notes Kerala Syllabus  Lightning

Lightning is the electric discharge between charged clouds in the atmosphere or between charged clouds and the earth

Basic Science Class 8 Electricity And Lightning Kerala Syllabus Lightning conductor

To protect the buildings from lightning, an earthed conductor with pointed end is placed on the highest part of the building. This is lightning conductor.

Methods to protect from lightning

• Do not operate electrical equipment
• Do not lean on the wall of the house.
• Do not stand holding windows bar or grill
• Do not stand beneath tall trees
• Do not take shelter under isolated trees
• Do not stand at open place
• A person struck by lightning should be made to lie in a place where there is good air circulation. In order to prevent blood clotting keep the body warm by massaging. Give artificial respiration and press strongly on the chest to maintain ‘ heartbeat and the person must be taken to a hospital immediately

Static Electricity Textbook Questions and Answers

Basic Science Class 8 Chapter 10 Electricity And Lightning Question 1.
From which one to which does electronic transfer occur when the pair of substances given below are rubbed against each other?
a. Glass rod – Silk doth
b. Ebonite – Wool
Answer:
a. From glass rod to silk
b. From wool to ebonite

Static Electricity Questions And Answers Kerala Syllabus Question 2.
Among the substances given below, which cannot be electrified by friction? Why? Amber, Plastic, Hacksaw blade, PVC pipe.
Answer:
Hacksaw blade. Because it is metal

Static Electricity Class 8 Questions Kerala Syllabus Question 3.
lightning conductors, which are not properly earthed, produce disaster rather than benefit. Justify this statement.
Answer:
Even though all the lightning will not affect the building, if there is lightning conductor the opposite charge of that in the clouds is induced on the pointed end of the conductor. If there is no earthing the flow of electron will be from the building to the conductor or to the building which causes accident

8th Class Biology Notes Pdf Malayalam Medium Kerala Syllabus Question 4.
What are the precautions to be taken for protecting ourselves from lightning?
Answer:

• Do not operate electrical equipments
• Do not lean on the wall of the house.
• Do not stand holding windows bar or grill
• Do not stand beneath tall trees
• Do not take shelter under isolated trees

Static Electricity Class 8 Kerala Syllabus Question 5.
How would you convert a copper plate kept in an electroscope into an arrangement for storing charge for a long time, through induction?
Answer:
Place copper sheet around the leaves of an electroscope. Touch the nob with a charged, body. Opposite charge is formed on the leaves. Opposite charge of it is formed inside the sheet and the same charge is formed outer surface of the sheet. Now the sheet is earthed, the charge on outer surface will be disappeared.

Static Electricity Additional Questions & Answers

Kerala Syllabus 8th Standard Chemistry Notes Malayalam Medium Question 1.
Complete the table

Objects	Electron exchange	Positive	Negative
Glass, silk	From glass rod to silk	….. a …..	Silk
Ebonite, wool	Wool to ebonite	…. b ….	…. c ….
Rubber rod, wool	…. d ….	Wool	…. e…

Answer:
a. Glass
b. Wool
c. Ebonite
d. From wool to rubber rod
e. Rubber rod

Kerala Syllabus 8th Standard Chemistry Notes English Medium Question 2.
When a glass rod is rub with silk electron loses from the glass rod. If we bring another glass rod near to it what can be observed? Give reason
Answer:
They will repel. Same charges repel each other.

8th Standard Chemistry Textbook Kerala Syllabus Question 3.
Tick the correct one
1. Object with same charge attract/repel
2. The charged body attract/ repel the neutral body
3. bodies with different charges attract/repel.
Answer:
1. repel
2. attract
3. attract

Static Electricity Questions And Answers Pdf Kerala Syllabus Question 4.
What is the use of capacitor?
Answer:
To store the charge

Electricity For Class 8 Kerala Syllabus Question 5.
What is earthing?
Answer:
Connecting an object to earth with a conductor is called earthing.

Question 6.
Examine the following figures and mark the point which charge is accumulated.

Answer:

Question 7.
Complete the figure.

Answer:

Question 8.
Why does the pointed edged con-ductors are used as lightning conductor
Answer:
The charge accumulated at the pointed edge easily and discharge it to earth immediately. So the building is not affected by lightning

Question 9.
What are the precautions to be taken when lightning
Answer:

• Do not operate electrical equipment
• Do not lay on the wall of the house.
• Do not stand holding windows bar or grill
• Do not stand beneath tall trees
• Do not take shelter under isolated trees

Question 10.
What are the primary steps to be adopted when a person is struck by lightning
Answer:
A person struck by lightning should be made to lie in a place where there is good air circulation. In order to prevent blood clotting keep the body warm by massaging. Give artificial respiration and press strongly on the chest to maintain heartbeat and the person must be taken to a hospital immediately

Question 11.
What is dielectric
Answer:
The dielectric are the insulators used in between the plates of the capacitor to increase its capacity Eg. Plastic, polyester, air, paper

Question 12.
What is capacitance? What is its unit
Answer:
capacitance is the ability to store the charge in it. Its unit is fared(F).
1F = 10⁶ μF(microfarad) 1F = 10^{12 μ}F (picofarad)

Question 13.
You might have seen iron chains, suspended from the body of lorries and trucks touching the earth. What is this for?
Answer:
These lorries and trucks have to travel a long distance. Sometimes the friction between rod and tire or vehicle and oil in it produces static electricity. This discharge gathers at one end of the truck and it causes sparking and from it the petrol may catch fire. The iron chains suspended from the body of lorries and trucks provide earthing and help to avoid the hazard.

Question 14.
The installation of lightning conductors is not insisted in may tall modern concrete buildings, nowadays. How are they protected from lightning?
Answer:
In tall modern buildings, there are plenty of metal rods inside the concrete work, connecting from the top to bottom of the building and to the earth. Electric charge from the lightning clouds, reaching the building, is conducted safely to the earth through these metal rods. So the building are protected from damage due to lightning discharge

Question 15.
A person takes shelter under a tree during heavy rain. Another person shelters under a coconut tree of same height. Who will be safer during lightning? Why?
Answer:
The person standing under the tree is safer. Electric charge always get concentrated at sharp edges. So more possibility for danger due to lightning is to the man under coconut tree than the. another one

Question 16.
There are two houses nearby, both of them having T.V. antenna pipes. One of these pipes is earthed. Write down the advantages or disadvantages of earthing the pipe.
Answer:
Advantage:
When lightning strikes the antenna it does not affect the house if the antenna pipe is earthed. The electric charge of the lightning goes to the earth through the pipe and so it acts as a lightning conductor.

You can Download इंद्रधनुष धरती पर उतरा Questions and Answers, Summary, Activity, Notes, Kerala Syllabus 8th Standard Hindi Solutions Unit 4 Chapter 1 help you to revise complete Syllabus and score more marks in your examinations.

Kerala State Syllabus 8th Standard Hindi Solutions Unit 4 Chapter 1 इंद्रधनुष धरती पर उतरा (चित्र-कहानी)

इंद्रधनुष धरती पर उतरा Summary in Malayalam and Translation

आकाश में रहते रहते मैं ऊब गया हूँ। क्यों न धर्ती पर ही चला जाऊँ!!!

सप्तम एक सुंदर-सी घाटी में उतर आया। दिन-भर वह घाटी में घूमता रहा। अंधेरा होने पर वह एक घने पेड़ के पास पहुंचा।

क्या मैं तुम्हारी टहनियों पर आराम कर सकता हूँ?

तुम मेरी टहनियों पर नहीं रह सकते। यह तुम्हारे लिए सही जगह नहीं।

थका हारा सप्तम आगे बढ़ा। वह एक निर्झर के पास पहुंचा।

आज की रात मैं तुम्हारे पानी में सो जाऊँ?

माफ़ करो भाई। किसी झरने के पानी में इंद्रधनुष कैसे रह सकता है?

सप्तम एक लड़के के पास गया।

क्या मैं तुम्हारे घर में आराम कर सकता हूँ?

क्यों नहीं? तुम ज़रूर यहाँ आराम कर सकते हो। अब तो मेरा अपना इंद्रधनुष होगा।

झोंपड़ी के अंधकार में सप्तम के सुंदर रंग दिखाई नहीं दे रहे थे। वह उदास हो गया।

तुम अपने आकाश से भाग क्यों आए?

यहाँ के पेड़-पौधे, नदियाँ, पहाड़ और फल-फूल आकाश से कितने सुंदर दिखाई देते हैं !

अपने घर में मुझे रहने दिया। बहुत शुक्रिया। अब मुझे वापस जाना है।

लड़के ने उसे विदा दी। वर्षा की बूंदें बरसने लगीं। पूर्व में सूर्य की किरणें झलकने लगीं। सात रंगोंवाला इंद्रधनुष चमकने लगा। सप्तम फिर से अपना घर पहुँच गया था।

इंद्रधनुष धरती पर उतरा शब्दार्थ Word Meanings

You can Download Solutions Questions and Answers, Summary, Activity, Notes, Kerala Syllabus 8th Standard Basic Science Solutions Chapter 15 help you to revise complete Syllabus and score more marks in your examinations.

Kerala State Syllabus 8th Standard Basic Science Solutions Chapter 15 Solutions

Solutions Textbook Questions and Answers

Kerala Syllabus 8th Standard Chemistry Notes Question 1.
Given below are some solutions. Identify and write down the solvent and the solute present in them. (Hint: Those present in large amount is the solvent and that in small amount is the solute).

Answer:

Solution	Solvent	Solute
Saltwater	Water	Salt
Ornamental gold	Gold	Copper
Soda water	Water	CO2
Dilute hydro­chloric acid	Water	Hydrochlo­ric acid

Basic Science For Class 8 Chapter 15 Kerala Syllabus Question 2.
Haven’t you noticed the caption “Shake well before use” in certain medicine bottles?
a. To which class do the substances in them belong to? (Colloid, Solution, Suspension)
b. What is the relevance of such instructions on these bottles?
Answer:
a. Suspension
b. It is used after shaking well because it is settled down after a long time.

8th Class Biology Notes Pdf Malayalam Medium Question 3.
Given below are some activities and observations done by a student using samples of dilute rice water, saltwater, and muddy water.

a. Complete the table with the missing observations, 3
b. Classify these samples into solution, colloid, and suspension.
Answer:

8th Class Biology Notes Pdf Kerala Syllabus Question 4.
There are numerous instances in daily life where solutions are being used. Tabulate some of them.
Answer:

• To make artificial soft drinks
• To make coffee, tea, and juices
• For painting
• Plastering with cement

8th Standard Chemistry Notes Pdf Kerala Syllabus Question 5.
You are now familiar with different types of solutions.
a. What is the difference between saturated and supersaturated solutions?
b. How will you prepare a supersaturated solution of common salt?
c. Unsaturated and supersaturated solutions of copper sulfate are prepared in separate beakers and a crystal of copper sulfate is dipped into each one of them. What would be the observation after a day? Give reasons.
Answer:
a. Saturated solution – The solution in which maximum amount of solute is dissolved A solution which contains more amount of solute than that is required to saturate it is known as Supersaturated solution.
b. Prepare a saturated solution dissolving salt in water. Then the solution is heated and dissolves more solute in it.
c. The size of crystal in the Supersaturated solution increases. This is because of the excess solute stacked on the crystal.

8th Class Chemistry State Syllabus Question 6.
Classify and tabulate the mixtures given below into solution, colloid, and suspension:
Milk, fog, atmospheric air dilute acid, lime water, ink, smoke.
Answer:
Solution:- Dilute acid, atmospheric air
Colloid:- Milk, Smoke, Fog,
Suspension:- Lime water

Solutions Additional Questions & Answers

Hsslive Guru Chemistry 8 Kerala Syllabus Question 1.
Tabulate the components of solution given below.
(saltwater, soda water, ornamental gold, air)
Answer:

Solution	Components
Saltwater	Salt, Water
Soda water	C02 Water
Ornamental gold	Gold, Copper
air	Nitrogen, Hydrogen, CO2, Oxygen, etc

8th Standard Physics Notes Pdf Kerala Syllabus Question 2.
Complete the table.

Answer:
a. Solid
b. Gas
c. Liquid
d. Liquid
e. Liquid
f. Solid
g. Liquid
h. Liquid

Basic Science Class 8 Chapter 15 Kerala Syllabus Question 3.
A child took 3 glasses of equal quantity of water and put half teaspoon salt in one glass and two teaspoon salts in the other. Which is the concentrated solution? Justify your answer.
Answer:
The concentrated solution is in the second glass because the amount of solute is greater in quantity in a concentrated solution

Kerala Syllabus 8th Standard Physics Notes Question 4.
What are the factors affecting the solubility?
Answer:
The nature of solute and the temperature

Kerala Syllabus 8th Standard Chemistry Notes Malayalam Medium Question 5.
Classify the following mixtures as Homogeneous and Heterogeneous
Sugar solution, muddy water, mixture of water and kerosene, salt solution, air, smoke
Answer:

Homogeneous	Heterogeneous
Sugar solution	Mixture of water anc kerosene
Salt solution Air	Muddy water Smoke

8th Class Biology Notes Pdf Kerala Syllabus Question 6.
Tabulate the two differences of solution and colloid.
Answer:

Solution	Colloid
The size of particle solute is very less	The size of particle is of comparatively larger
Cannot scatter the light, therefore, it is not visible	Scatter the light and therefore path of light is visible

Basic Science Class 8 Ch 15 Kerala Syllabus Question 7.
Tabulate the differences between solution and suspension.
Answer:

Solution	Suspension
Size of the particle very small	Can be seen by nak­ed eye
Cannot scatter the beam of light	Scatter the beam of light
Cannot separate by filtration	Can be separated by filtration
Particles are not se­ttled down when ke­ep if undisturbed	Particles are settled down

Kerala Syllabus 8th Standard Biology Notes Malayalam Medium Question 8.
Why does the path of light seen when dust particles are spread in cinema theatre and smart room.
Answer:
When dust particles are spread in air the air becomes suspension. Then it can scatter the light and so the path can be seen

Scert Class 8 Science Notes Kerala Syllabus Question 9.
What is meant by stabilizer; give example.
Answer:
The soft drinks available in market do not settle down even after prolonged storage. To retain as such for long time without settling down some chemicals are added to it. These are called stabilizers.
Eg. Brominates vegetable oil.

Basic Science Class 8 Solutions Kerala Syllabus Question 10.
Explain what are saturated and supersaturated solution?
Answer:
The solution obtained by dissolving maximum amount of solute at a given temperature is known as saturated solution. A solution which contains more amount of solute than that is required to saturate it is known as supersaturated solution.

8th Standard Chemistry Textbook Kerala Syllabus Question 11.
How can we prepare the supersaturated solution of salt?
Answer:
Prepare a saturated solution dissolving salt in water. Then the solution is heated and dissolves more solute in it

Class 8 Basic Science Chapter 15 Kerala Syllabus Question 12.
What are crystals; How can we make growing crystals?
Answer:
Prepare a saturated solution of a sol-ute like copper sulfate. When we allow it to evaporated slowly, the crystals are appeared. Select a suitable crystal and hang it in the solution with a twain. After a few days, the crystal can be seen grown as well.

Question 13.
Collect the names of the preservative commonly used and write its the side effects.
Answer:
Common salt, sugar, acetic acid, sodium meta bisulfate. Overuse of salt causes hypertension (blood pressure). Use of sugar effects badly on diabetic patients. Acetic acid causes acidity.

Question 14.
What is “Tyndall effect”
Answer:
The colloidal particles can scatter light and so we can see them. This is Tyndall effect.

You can Download Equal Triangles Questions and Answers, Activity, Notes, Kerala Syllabus 8th Standard Maths Solutions Chapter 10 help you to revise complete Syllabus and score more marks in your examinations.

Kerala State Syllabus 8th Standard Maths Solutions Chapter 10 Statistics

Statistics Text Book Questions and Answers

Textbook Page No 184

Class 8 Maths Chapter Statistics Kerala Syllabus Question 1.
The number of members in 50 households of a village are listed below.

Make a frequency table and answer these questions:
i. How many households have just two members?
ii. How many households have four or less?
iii. How many households have ten or more?
iv. Households of what size occurs the most?
Solution:

i. 5
ii. 5 + 11 + 9 = 25
iii. 1 + 1 = 2
iv. 3

8th Standard Maths Statistics Kerala Syllabus Question 2.
There are 44 children in class 8B. The list shows how far they come from, in kilometres.

Make a frequency table and answer these questions:
i. How many children are from exactly 1 kilometre away?
ii. How many are from more than 5 kilometres?
iii. How many are from between 5 and 10 kilometres?
iv. How many are from more than 10 kilometres?
Solution:

i. 3
ii. 21
iii. 23
iv. 4

8th Standard Maths Guide Kerala Syllabus  Question 3.
The scores of 35 children in a test are given below:

Make a frequency table and answers these questions:
i. How many children scored 20?
ii. How many children got scores between 10 and 20?
iii. How many scored less than 10?
iv. What is the score most number of children got?
Solution:
Score Tally Number of children

i. 1
ii. 32
iii. 0
iv. 15

Textbook Page No 188

Statistics Class 8 Notes Kerala Syllabus Question 4.
Given below are the highest temperatures (in degree Celsius) one day in 40 towns. Make a frequency table.

Solution:

8th Class Maths Statistics Kerala Syllabus Question 5.
The heights (in centimeters) of 45 people who look part in a physical fitness test are given below? Make a frequency table.

Solution:

Textbook Page No 190

Hss Live Guru Maths 8th Kerala Syllabus Question 6.
The table shows the times 30 children took to complete a long distance race. Draw a histogram of this.

Solution:

Hsslive Guru Maths 8th Standard Kerala Syllabus Question 7.
The table shows the daily incomes of 6o households in a locality.

Draw a histogram.
Solution:

Hss Live Std 8 Maths Kerala Syllabus Question 8.
Detail of rainfall in June and July are given in the table below. Draw a histogram.

Solution:

Hsslive Guru 8th Class Maths Kerala Syllabus Question 9.
The time taken by 25 women and 23 men to complete a race are given in the table below. Draw separate histograms for men and women.

Solution:

Kerala Syllabus 8th Standard Maths Notes Question 10.
The weights of 45 children in a class are listed below.


Make a frequency table and draw a histogram.
Solution:

Additional Questions And Answers

8th Standard Maths Kerala Syllabus Question 1.
Complete the table below on the basis of the histogram.

Solution:

8th Class Maths Notes Kerala Syllabus Question 2.
Teacher conducted a test in her class of 45 students. Their score out of a total of 10 are given below.

a. Construct a frequency table representing these details?
b. Construct a bar graph?
Solution:

Hss Live Guru Class 8 Maths Kerala Syllabus Question 3.
The list below gives the daily wages earned by 30 laboures. Prepare a frequency table of these.

a. What is the daily wages of most labourers?
b. How many get 250 rupees a day?
c. How many get the least amount of wages?
Solution:

a. 225
b. 6
c. 5

Class 8 Maths Chapter 10 Kerala Syllabus Question 4.
The table shows daily expenditure of 60 household in a locality. Draw histrogram.

Solution:

8th Standard Maths Notes Kerala Syllabus Question 5.
Given below are the amount of rainfall (in mm) one day in 61 towns. Make a frequency table.


Solution:

8th Std Maths Solution Guide Kerala Syllabus Question 6.
The runs that a batsman got in 40 one – day cricket matches are given below. Make a frequency table and answer these questions.

a. How many centuries did he get?
b. How many half centimes?
c. In how many games did he score less than 50?
Solution:

Question 7.
The height of 30 childrens in a class are listed below. Mark a frequency table and draw a histogram.

Solution:

You can Download दोहे Questions and Answers, Summary, Activity, Notes, Kerala Syllabus 8th Standard Hindi Solutions Unit 3 Chapter 3 help you to revise complete Syllabus and score more marks in your examinations.

Kerala State Syllabus 8th Standard Hindi Solutions Unit 3 Chapter 3 दोहे (कविता)

दोहे Summary in Malayalam and Translation

बड़ा हुआ तो क्या हुआ, जैसे पेड़ खजूर।
पंथी को छाया नाहिं, फल लागै अतिदूर।।

Kabir Ke Dohe Hindi Poem 8th Standard भावार्थ :
इस दोहे में कबीरदास कहते हैं कि खजूर के पड़ के समान बडा होने से कोई फायदा नहीं है। बहुत लंबा होने के कारण पथिक को छाया नहीं मिलती है। फल भी बहुत ऊँचाई पर लगते हैं। वह भी लोगों केलिए अप्राप्य है। मतलब है कि हम बड़े होकर भी दूसरों को कोई उपकार नहीं करते तो उस बडप्पन से किसी को कोई लाभ नहीं। दूसरों की भलाई करनेवाले ही सच्चे अर्थ में बडे होते हैं।

रहीम वे नर धन्य हैं, पर उपकारी अंग।
बाँटन पारे को लगे, ज्यों मेहंदी को रंग।।

8th Class Hindi Dohe Kerala Syllabus भावार्थ :
रहीस कहते हैं – वे नर धन्य है जिनका शरीर सदा सबका उपकार है। जिसप्रकार मेहंदी बाँटनेवाले के अंग पर भी मेहंदी का रंग लगा जाता है उसी प्रकार परोपकारी का शरीर भी सुशोभित होता है। .

Rahim Ke Dohe Question Answer Kerala Syllabus दोहे शब्दार्थ Word meanings

You can Download जल-बैंक Questions and Answers, Summary, Activity, Notes, Kerala Syllabus 8th Standard Hindi Solutions Unit 4 Chapter 3 help you to revise complete Syllabus and score more marks in your examinations.

Kerala State Syllabus 8th Standard Hindi Solutions Unit 4 Chapter 3 जल-बैंक

जल-बैंक पाठ्यपुस्तक के प्रश्न और उत्तर

Jal Bank Hindi Story Kerala Syllabus 8th प्रश्ना 1.
‘चप्पे-चप्पे पर जल बैंक खुल गए हैं।’ लेखक की इस कल्पना के पीछे भविष्य का कौन-सा संकेत है?

उत्तर:
पानी की कमी एक गंभीर समस्या बनती जा रही है। अब भी हम इस दिशा पर ध्यान न रखेंगे तो भविष्य बड़ी आपत्ति हो जाएगी। पानी के लिए हमें किसी जल बैंक जैसी व्यवस्थाओं का आश्रय लेना पड़ेगा।

Hss Live Guru 8 Hindi Kerala Syllabus प्रश्ना 2.
‘पानी-पानी होना’, ‘पानीदार होना’ आदि प्रयोगों का मतलब क्या है?

उत्तर:
‘पानी-पानी होना’ का मतलब है- अत्यंत लज्जित होना और ‘पानीदार होना’ का मतलब होना- धनी होना।

Hss Live Guru Hindi 8th Kerala Syllabus प्रश्ना 3.
‘घर में पीने के वास्ते भी एक बूंद नहीं है’ लोग ऐसा झूठ क्यों कहते हैं?

उत्तर:
पानी की कमी बहुत है। लेकिन कुछ लोग उसके उपयोग में सावधानी नहीं बरते। कुछ लोग पानी के बिना तरसते हैं। उनके सामने लोग झूठ बोलते हैं कि पीने के लिए भी एक बूंद पानी नहीं है। यहाँ लोगों की संकुचित भाव की ओर संकेत है।

Hss Live Guru 8th Hindi Kerala Syllabus प्रश्ना 4.
‘चारों उँगलियाँ पानी में’ इस प्रयोग से आप क्या समझते हैं?

उत्तर:
‘चारों उँगलियाँ पानी में’ का मतलब है- जीवन में बड़ा नुकसान होना।

जल-बैंक Textbook Activities

Hsslive Guru Hindi Class 8 Kerala Syllabus प्रश्ना 1.
चर्चा करें।
जल बैंक की संकल्पना कैसी लगी?
वर्तमान समाज में इसकी प्रासंगिकता क्या है?

उत्तर:
जल दुर्लभता आज की विकट समस्या है। ऐसी स्थिति में जलबैंक की संकल्पना उचित है।

Hsslive Guru 8th Hindi Kerala Syllabus प्रश्ना 2.
जल-संरक्षण की आवश्यकता पर नारे बनाएँ।

जल है तो कल है।
जल जीवन का आधार।
जल नहीं तो हम नहीं।
जल ही जीवन है।
बूंद-बूंद का संरक्षण, जीवन का संरक्षण।
आज संजोएँ हरेक बूंद, कल को बनाएँ खूब सुहाना।

Hsslive Guru 8th Class Hindi Kerala Syllabus प्रश्ना 3.
उपर्युक्त नारों की मदद से पोस्टर तैयार करें।

जल-बैंक Summary in Malayalam and Translation

 जल-बैंक शब्दार्थ Word meanings

You can Download Basic Constituents of Matter Questions and Answers, Summary, Activity, Notes, Kerala Syllabus 8th Standard Basic Science Solutions Chapter 5 help you to revise complete Syllabus and score more marks in your examinations.

Kerala State Syllabus 8th Standard Basic Science Solutions Chapter 5 Basic Constituents of Matter

Basic Constituents of Matter Questions and Answers

The particles in sugar candy and potassium permanganate solutions cannot be seen as they are extremely small. If we take one or two pieces of camphor in a china dish and heat the china dish. Even though the camphor has disappeared completely, the smell of camphor remains in air. This is because the camphor has spread in air as extremely small particles.

Fill one quarter of a boiling tube with sugar and close it with cotton. Then heat the boiling tube strongly. The water in sugar is sticked on the sides of the boiling tube as water vapour. Carbon and water are the components of sugar. Water can be further divided. When electricity is passed through water it splits into hydrogen and oxygen. That is sugar, a pure substance, can be divided into carbon, hydrogen, and oxygen. At the same time, pure substances like carbon, hydrogen, oxygen, gold, and silver cannot be further divided into its components by chemical reactions.

Basic Constituents Of Matter Class 8 Kerala Syllabus Elements and Compounds

The pure substances which cannot be further decomposed through chemical processes are called elements.
Ex: hydrogen, oxygen, gold, silver Compounds are pure substances formed from two or more elements through chemical combination.
Ex : water, sugar, carbon dioxide

Origin of the names of elements

In the past, the elements were named after places, countries, continents, characteristic properties, scientists, planets, satellite etc.
Ex : Place – polonium, francium
Continent – Europium, Americium
Character, colour – rubedium, chromium
Scientist – bohrium, curium
Planet – neptunium

Basic Constituents Of Matter Class 8 Questions And Answers Kerala Syllabus Symbols

The first letter of the English or latin letters are used as the symbols of the ele-ments.
Ex: Carbon – C
Oxygen – O
Sodium-Natrium – Na
Potassium-Kalium – K
But, for some elements, along with the first letter, the second or another prominent letter is also used in the symbol as a small letter.
Ex: Calcium – Ca
Chlorine – Cl

Basic Constituents Of Matter Class 8 Notes Pdf Kerala Syllabus Atom and Molecule

The element carbon is made up of extremely small particles. Think of breaking a piece of carbon into smaller and smaller particles. When it is broken up in this manner, we get the smallest particle which retains all the characteristic properties of carbon at the end. This smallest particle is called an atom of carbon.

Atoms of some gaseous elements like helium, neon etc., can exist as free single atoms. But atoms of some other gaseous elements like hydrogen, oxygen etc., can exist only as a combination of two atoms. Atoms of some elements are seen to exist as a combination of more than two atoms. The smallest particles which can exist independently are called molecules.

Method of representing Atoms and Molecules

The symbol of helium is ‘He’. When we write ‘He’, it represents one atom of the element helium. 2He means two helium atoms.

Elements like helium, neon, argon, etc., are seen in nature as single atoms. But elements like hydrogen exist as diatomic molecules. Hydrogen atom is represented as H. But H₂ represents a hydrogen molecule.

Some elements exist as molecules of more than two atoms. Phosphorus (P₄), sulphur (S₈), etc., are examples of such
elements.

Molecules with only one atom are called monatomic molecules.
Ex: He, Na

Those with two atoms each are called diatomic molecules.
Eg: O₂, H₂, N₂

The molecules with more than two atoms are called polyatomic molecules.
Eg: P₄ S₈

In monatomic molecules, the number given on the left side of the symbol indicates the number of molecules and atoms. In polyatomic molecules, the subscript on the right side of the symbol indicates the number of atoms within one molecule. The total number of molecules is indicated on the left side.
O – One oxygen atom
O₂– One oxygen molecule
2O₂ – Two oxygen molecules
2He – Two helium atom/molecule
5Na – five sodium atoms

Basic Constituents Of Matter Kerala Syllabus  Compounds

We have seen how molecules are formed from the same type of atoms. Similarly, the compounds contain molecules formed from atoms of different elements.

Carbon dioxide molecule is formed when one carbon atom combines with one oxygen atom.

This is a compound. Water is a compound formed by the combination of hydrogen and oxygen.

Carbon dioxide is formed when carbon burns in oxygen. Carbon dioxide is also formed by the decomposition of calcium carbonate. Whatever be the sourcj of a compound, a fixed ratio is maintained between the atoms of the different elements present in it. In carbon dioxide molecule, the ratio of carbon atoms to oxygen atoms is always 1: 2. Thus carbon dioxide molecule can be represented as CO₂. Similarly in water molecule the ratio of hydrogen and oxygen atom is 2:1 This type of representation is known as the chemical formula of the compound.
H₂SO₄ ,CO₂ ,H₂O, HCl, NaCl

2CO₂ represents two carbondioxide molecules. We can understand that there are 6 atoms including 2 carbon atoms and 4 oxygen atoms in 2CO₂.

There are 7 atoms including 2 hydrogen atoms, 1 sulphur atom and 4 oxygen atoms in H₂ SO₄, Molecule. There will be 14 atoms in 2H₂ SO₄

Basic Constituents Of Matter Notes Kerala Syllabus Chemical Equations

The chemical equation of the reaction between zinc and hydrochloric acid forming zinc chloride and hydrogen is written as shown below.
Zn+HCl → ZnCl₂ + H₂

Here Zn and HCl are reactants. ZnCl₂ and H₂ are products.

The chemical reactions can be represented as equations containing the symbols and chemical formulae of the reacta¬nts and the products. When a chemical equation is written, the number of atoms of the same kind, on the side of reactants and that of products should be equal. That is the chemical equation given above is to be rewrite as
Zn + 2 HCl → ZnCl₂ + H₂

Now the number of atoms in both side of the arrow is equal. This type of chemical equations which is written such that the number of atoms of same type is equal in the side of reactants and products are called balanced chemical equations.

Basic Constituents of Matter Textbook Questions and Answers

Basic Science Class 8 Chapter 5 Kerala Syllabus Question 1.
Classify the following into elements and compounds. Ammonia, sugar, nitrogen, mercury, sodium chloride, water, copper sulphate, sodium, carbon.
Answe:

Elements	Compounds
Mercury	Ammonia
Sodium	Sugar
Carbon	Sodium chloride
Nitrogen	Water
	Copper sulphate

Hsslive Guru 8th Class Chemistry Kerala Syllabus Question 2.
Analyse the chemical equation given for the reaction between nitrogen and hydrogen to give ammonia.
N₂+3H₂ → 2NH₃
a. What are the reactants and products in this reaction?
b. Find the total number of molecules and atoms of the reactants.
c. Find the total number of molecules and atoms of the products.
d. What is the relation between the number of atoms of the reactants and products?
Answer:
a. Reactants: nitrogen, hydrogen Product: ammonia (NH₃)
b. Total number of molecules in reactant – 4 total atoms- 8
c. Total number of molecules in product -2 total atoms- 8
d. Total number of atoms in reactants and products are equal.

Hsslive Guru Chemistry 8 Kerala Syllabus Question 3.
N is the symbol of nitrogen.
a. What do N₂, 2N and 2N₂ indicate?
b. How many molecules and atoms are present in 5N₂?
Answer:
a. N₂ – One nitrogen molecule
2N – Two nitrogen atoms
2N₂ – Two nitrogen molecules
b. 5N₂ – 10 atoms, 5 molecules

Hss Live Guru 8th Chemistry Kerala Syllabus Question 4.
Some chemical equations are given.
C + O₂ → CO₂
CH₄ + 2O₂ → CO₂ + 2H₂O
N₂ + O₂ → NO
CaCO₃ → CaO + CO₂
H₂ + I₂ → HI
Fe + HCl → FeCl₂ + H₂
CO₂ + C → CO
a. Which of these are balanced chemical equations?
b. Balance those equations which are not balanced.
Answer:
a. C + O₂ → CO₂
CH₄ + 2O₂ → CO₂ + 2H₂O
CaCO₃ → CaO + CO₂

b. N₂ + O₂ → 2NO
H₂ + I₂ → 2Hl
Fe + HCl → FeCl₂ + H₂
CO₂ + C → 2CO

Basic Science Class 8 Solutions Kerala Syllabus Question 5.
Find whether the following statements are right or wrong.
a. All atoms of the same element show the same properties.
b. The atoms present in a compound are different.
c. Elements are pure substances.
d. Hydrogen is a monatomic molecule
Answer:
a. True
b. True
c. True
d. False

Matter And Chemical Formula Class 7 Kerala Syllabus Question 6.
Take iron powder and sulphur powder in their mass ratio of 7:4 in a china dish. Heat it strongly for some time.
a. Try to separate the iron powder using a magnet. What can be observed? What is the reason?
b. Add a .little dilute hydrochloric acid to the above product; observe the changes taking place, and write them down.
c. Write down the inferences you have arrived at from these observations.
Answer:
Sulphur is reacted with iron powder to form ferrous sulphide therefore it cannot be separated.
There will be the smell of rotten egg because hydrogen sulphide is produced.

8th Class Chemistry State Syllabus Kerala Syllabus Question 7.
Make and exhibit the models of the following molecules using ball and sticks, different fruits and splints.
a. Water (H₂O)
b. Ammonia (NH₃)
c. Carbon dioxide (CO₂)
d. Methane (CH₄)
Answer:
Do your self

Basic Science Class 8 Pdf Notes Kerala Syllabus Question 8.
Haven’t you understood how symbols are assigned to elements? Given below are some elements that received symbols from their Latin names. Complete the table with the help of the Periodic Table.

 

Element	Latin name	Symbol
Silver	……………..	……………..
……………..	Hydrargium	……………..
Tin	……………..	……………..
……………..	……………..	Pb
Antimony	……………..	……………..
……………..	Aurum	……………..

Answer:

Element	Latin name	Svmbol
Silver	Arguntum	Ag
Mercury	Hydrargium	Hg
Tin	Stannum	Sn
Lead	Plumbum	Pb
Antimony	Stibium	Sb
Gold	Aurum	Au

Basic Constituents of Matter Additional Questions and Answers

Basic Science Question Answer Chapter Wise Class 8 Kerala Syllabus Question 1.
Choose the correct symbol of the elements given below from the box.
(Calcium, carbon, sodium, potassium, Iron, silver)
(S, C, Na, Ca, Si, Ag, In, P, K, Fe)
Answer:
Calcium-Ca,
Carbon-C,
Sodium- Na,
Potassium- K,
Iron- Fe,
Silver- Ag

Basic Science For Class 8 Chapter 5 Kerala Syllabus Question 2.
The chemical formula of calcium bisulphate is Ca (HSO₄)₂. Write down the number of atoms of each element present in this molecule.
Answer:
Ca=1, H=2, S=2, 0=8

Basic Science Class 8 Kerala Syllabus Question 3.
Na. This is the symbol of an element. Which statement given below is wrong. Justify?

• Symbol of Nitrogen
• Indicates one atom.

Answer:
Symbol of Nitrogen.
The symbol that represent the element Nitrogen is ‘N’. ‘Na’ is the symbol of sodium.

8th Class Chemistry Notes Pdf Kerala Syllabus Question 4.
We know about elements and compounds. Find out the odd one from the following. Give reason?
a. (A) Hydrogen (B) Oxygen (C)Nitrogen (D) Carbon dioxide
b. (A) Sodium (Na), (B) Pottasium (K) (C) Magnesium (Mg), (D) Iron (Fe)
c. Write the molecular formula of carbon dioxide?
d. What is the Latin name of sodium?
Answer:
a. Carbon dioxide – Compound, others are elements.
b. Magnesium – Others take symbols from their Latin name.
c. CO₂
d. Natrium

8th Std Basic Science Textbook Kerala Syllabus Question 5.
Arrange the following from smallest to largest.

Answer:
Atom → Molecule → Small particle → Substances

Physics Class 8 Kerala Syllabus Question 6.
Represent the basis of nomenclature of elements given in the following table.
a.

Element	Basis of nomenc­lature
Francium Rutherfordium

b. Which element symbol is Cl?
c. What are the constitute elements containing of CaF₂ molecule?
Answer:
a. Name of country
b. Name of scientist
c. Chlorine
d. Calcium, -Fluorine

Question 7.
Symbol of Nitrogen is ‘N’.
a. What represent symbols of 2N and N₂?
b. How many atoms are in 2NH₃?
c. How can represent 5 water molecules?
Answer:
a. 2N represent 2 atoms of Nftrogen. N₂ represent Nitrogen molecules can be formed by combining two atoms of Nitrogen.
b. 8 atoms
c. 5 H₂O

Question 8.
Evaluate the given chemical equation and answer the following questions.
SO₂ + O₂ – SO₃
a. Which are the reactants in the chemical reaction?
b. What is the product of the chemical reaction?
c. Write the balanced chemical equation?
Answer:
a. SO₂, O₂
b. SO₃
c. 2SO₂ + O₂ → 2SO₃

Question 9.
Find the monoatomic molecule from given elements.
a. (A) Hydrogen (B) Oxygen (C)Nitrogen (D) Helium
b. Write the symbols of Hydrogen and Helium?
c. Write chemical formula of Oxygen molecule?
d. What is the Latin name of sodium?
Answer:
a. (D) Helium
b. Hydrogen (H), Helium (He)
c. O
d. Natrium

Question 10.
Select the compounds from the following:
HCl, CO₂, O₂, NaCl, H₂, H₂O, Na, HCl
Answer:
NaCl, CO₂, H₂O, HCl

Question 11.
Form a table of elements which are related to the name of scientists from the following Americum, Mentelivium, Titanium, Rutherfordium, Rubedium, Einstenium, Europeum, Bohrium
Answer:
Mentelivium, Rutherfordium, Einstenium, Bohrium

Question 12.
Examine the following symbols and write the name of elements Ca, Cr, Cl, Be, Na, Fe, Cu
Answer:
Calcium, Chromium, Chlorine, Berelium, Sodium, Iron, Copper

Question 13.
Fill in Blanks suitably
Element – Atom,
Compound – …………
Answer:
Element – Atom,
Compound – Molecule

Question 14.
Complete the following table

Element	Basis of Naming
Americum
Francium
Rubedium
Plutonium
Titanium
Mentalivium
Rutherfordium

Answer:

Element	Basis of Naming
Americum	America- continent
Francium	France – country
Rubedium	Ruby – Colour
Plutonium	Pluto- planet
Titanium	Titan – God
Mentalivium	Mentelief – Scientist
Rutherfordium	Rutherford – Scientist

Question 15.
Examine the following molecules and tabulate the atoms contained in them.
1. Carbon dioxide
2. hydrogen chloride
3. Water
4. sugar
5. Mercuric oxide
Answer:
1. C, O;
2. H, Cl
3- H, O;
4. H, C, O;
5- Hg, 0

Question 16.
Complete the tables

Element	English name	Symbol
Carbon	Carbon	C
Oxygen	………….	………….
………….	Nitrogen	………….
………….	………….	H

Answer:

Element	English name	Symbol
Carbon	Carbon	C
Oxygen	Oxygen	0
Nitrogen	Nitrogen	N
Hydrogen	Hydrogen	H

Question 17.
Tabulate the number of atoms and molecules
5H₂, 2H₂ O, 3ZnCl₂, CO₂
Answer:

Compound	Number of atoms	Number of molecules
5H2	10	5
2H20	6	2
3ZnCl2	9	3
co2	3	1
co2	3	1

Question 18.
Write the diatomic molecules from the following
H₂, Na, C, N₂, P₄, O₂
Answer:
H₂, N₂, O₂

Question 19.
Complete the table

Monatomic	Diatomic	Polyatomic
………..	H2	P4
Na	………..	………..
He	………..	………..

Answer:

Monatomic	Diatomic	Polyatomic
C	H2	P4
Na	O2	O3
Ne	N2	S8
He	Cl2

Question 20.
How many hydrogen and sulphur atoms are there in H₂SO₄ molecule?
Answer:
Hydrogen-2 Sulphar-1

Question 21.
Complete the table.

Substance	No. Of molecules	No. of atoms
P4
02
5Na
2Na
6Cl2
2He

Answer:

Substance	No. Of molecules	No. of atoms
P4	1	4
02	1	2
5Na	5	5
2Na	2	2
6Cl2	6	12
2He	2	2

Question 22.
Find the total number of atoms in the following molecules
a. CO
b. 5 H₂O
c. 7 NH₃
d. 2 Cl₂ H₂₂ O₁₁
e. 3 NaCl
f. ZnCl₂
Answer:
a. CO – 2
b. 5 H₂O -15;
c. 7 NH₃ – 28;
d. 2C₂ H₂₂ O₁₁ – 90
e. 3 NaCl – 6
f. ZnCl₂ – 3

Question 23.
The chemical formula of water is H₂O. Write the ratio of hydrogen and oxygen atoms in water molecule.
Answer:
Ratio of hydrogen and oxygen is 2:1

Question 24.
Tabulate the reactants and products in the following chemical equation.
1. 2H₂ + O₂ → 2H₂O
2. Na + Cl₂ → 2NaCl
3. C + O₂ → CO₂
4. H₂ +Cl₂ → 2HCl
Answer:

Question 25.
Balance the following equations which are not balanced.
C + O₂ → CO₂
H₂ + N₂ → NH₃
Mg + O₂ → Mgo
2H₂ + O₂ → 2H₂O
Answer:
3 H₂ + N₂ → 2NH₃
2Mg+O₂ → 2MgO

Question 26.
How did the symbol system introduced by Berzelius, help the study of chemistry?
Answer:

• The study of chemistry became simple and easy.
• Writing chemical equations representing chemical reactions became very easy.
• The number of atoms in a molecule can be found out from the symbol of the molecule of the element.

Question 27.
Balance the equation
1. NaOH + H₂ SO₄ → Na₂ SO₄ + H₂O
2. H₂O₂ → H₂O + O₂
3. CH₄ + O₂ → CO₂ + H₂O
4. NaOH + HCl → NaCl + H₂O
5. H₂O + CO₂ → C₆H₁₂O₆ + O₂
Answer:
2NaOH + H₂SO₄ → Na₂SO₄ + 2H₂O
2H₂ O₂ → 2HO₂ + O₂
CH₄ +O₂ → CO₂ + 2H₂O
2NaOH + 2HCl → 2NaCl + 2H₂O
6 H₂O + 6CO₂ → C₆ H₁₂ + 6 O₂

You can Download Sound Questions and Answers, Summary, Activity, Notes, Kerala Syllabus 8th Standard Basic Science Solutions Chapter 19 help you to revise complete Syllabus and score more marks in your examinations.

Kerala State Syllabus 8th Standard Basic Science Solutions Chapter 19 Sound

Sound is a form of energy which is familiar to us and necessary for communication. Three components are essential to experience the sound. Source of sound, medium, and the ear.

Source of sound

The sources that produce sound is called sources of sound. We can classify the sources of sound into two. Natural sources of sound and manmade sources of sound. Sound is produced by the vibration of object. The object that produces sound is called the source of sound.

Hss Live Guru 8th Physics Kerala Syllabus Natural frequency

When a body is set into vibration it vibrates with particular frequency of its own. This frequency is called its natural frequency. The unit of frequency is hertz (Hz). The constituents those affect the natural frequency of an object are the nature of the object, length of the object, surface area, tension of the object, etc.
Frequency (f) = Number of vibration(n)/ time(f)

Pitch and loudness

The sharpness of the sound heard is called the pitch. It depends on its frequency of sound. Cuckoo’s cry, female voice etc have high pitch and male voice, duck’s sound, lion’s roar, etc have low pitch. Loudness is the measure of audibility of a person. This depends mainly on frequency of sound and the sensory ability of the ear. Its unit is decibel (dB).

Kerala Syllabus 8th Standard Physics Notes Propagation of sound

A medium is necessary for sound to propagate. Sound is propagated not only through air but also through other substances. Loss of hearing is a disability of the ear. The people having damage to ear by birth effect many difficulties for commu¬nication, for ability to speak, vulnerability to danger, etc.

Class 8 Physics Notes Kerala Syllabus Limit of audibility

We cannot here sound of all frequencies. We can hear the sound of frequency in between 20 Hz and 20000Hz. Sounds with frequency less than 20 Hz are called infrasonic and that greater than 20000Hz are called ultrasonic. Ultrasonic sounds are used in the instrument sonar and in medical field.

Hss Live Guru 8th Basic Science Kerala Syllabus Noise pollution

Kerala is one of the places which is highest noise pollution in the world. Noise effects not only ear but mental, emotional level, and physical problems. Reduce the use of air horns, use silencers in vehicles, planting trees, etc are some ways to reduce noise pollution.

Sound Textbook Questions & Answers

Hsslive Guru Physics 8th Standard Kerala Syllabus Question 1.
If a tuning fork vibrates 480 times in one second, what would be its natural frequency?
Answer:
Natural frequency = 480Hz

Kerala Syllabus 8th Standard Chemistry Notes Question 2.
If a simple pendulum oscillates 10 times in 10 seconds, what would be its frequency?
Answer:
n = 10
t = -10 s
\(\mathrm{f}=\frac{n}{t}=\frac{10}{10 s}=1 \mathrm{Hz}\)

Hsslive Guru 8th Class Physics Kerala Syllabus Question 3.
What are the factors influencing the natural frequency of a body?
Answer:
i. Nature of the object
ii. Length
iii. Tention
iv. Surface area
v. Area of cross-section

Hss Live Physics Class 8 Kerala Syllabus Question 4.
The frequencies of certain tuning forks are given below. Find out which among these have the highest and the smallest pitches.
(256 Hz, 512 Hz, 480 Hz, 288 Hz)
Answer:
High pitch = 512 Hz
Low pitch = 256 Hz

Kerala Syllabus 8th Standard Basic Science Notes Question 5.
In the sources of sound given below, vibration in which main part produces sound?
a. Chenda
b. Flute
c. Vocal cord
Answer:
a. Chenda – Diaphragm
b. Flute-Air
c. Vocal box – vocal cord

Kerala Syllabus 8th Standard Chemistry Notes Malayalam Medium Question 6.
Design an activity to prove that sound can he propagated even through solid substances.
Answer:
Answer:
Press the ear on one end of a iron rod and beat on the other end with another iron rod or, toy telephone

8th Standard Physics Notes Kerala Syllabus Question 7.
Say whether the following statements given below are true or false.
If false, rewrite it by making necessary changes.
a. Sound cannot travel through vacuum.
b. When frequency of sound increases, pitch decreases.
Answer:
a. correct
b. false, when frequency decreases pitch decreases

Kerala Syllabus 8th Standard Physics Question 8.
‘Bats can catch prey even in the dark’. Do you agree with this statement? Explain your inference.
Answer:
Agree. Bats can produce and hear ultrasonic waves. The sound they produced reflects by hitting on objects. The bats can analyze the returning sounds.

8th Class Biology Notes Pdf Kerala Syllabus Question 9.
How do human beings contribute to noise pollution?
Answer:

• Air horn
• Loudspeaker
• The sounds of vehicles etc

8th Standard Chemistry Notes Pdf Kerala Syllabus Question 10.
Which unit represents loudness? (Hz, m/s, dB, W)
Answer:
dB

Sound Additional Questions & Answers

8th Standard Chemistry Notes Kerala Syllabus Question 1.
Complete the table

Source of sound	The main part which produces sound by vibration	The part which vibrates with the main part
Voicebox	….. a ……..	Throat, lips
Flute	Air column	…. b …..
Chenda	Leather, diaphragm	…… c …….
Violine	……… d ……….	Frame, air

Answer:

Source of sound	The main part which produces sound by vibration	The part which vibrates with the main part
Voicebox	Vocal cord	Throat, lips
flute	Air column	Throat, air
chenda	Leather, diaphragm	wooden frame, cord
Violine	Metal Wire	Frame air

Basic Science Class 8 Sound Kerala Syllabus Question 2.
Fill suitably
Frequency – hertz; Loudness- ………….
Answer:
decibel (dB)

Class 8 Science Notes Kerala Syllabus Question 3.
Table the following as those having high pitch and low pitch separately.
Cuckoo’s cry, lion’s roar, female voice, duck’s sound, male voice, air horn
Answer:

high pitch	low pitch
Cuckoo’s cry	Lion’s roar
Female voice	Duck’s sound
Air horn	Male voice

Class 8 Physics Kerala Syllabus Question 4.
Table the natural source and manmade source from the following. Lips, chenda, flute, tabla, violin, vocal cord, sound of birds
Answer:

Natural	Man-made
Lips	Chenda
Vocal cord	Flute
Sound of bird	Tabala
Violin

Vibration Solutions Question 5.
What is the relation between the length of the pendulum and frequency?
Answer:
When the length of the pendulum increases, the frequency decreases.

Question 6.
Will the intensity of sound increase when the instrument like chenda and maddalam are beaten strongly? Justify your answer.
Answer:
Yes. When beaten strongly the diagram vibrates with greater amplitude and increases frequency and loudness

Question 7.
What are the demerits of sound pollution?
Answer:

• Causes mental stress.
• Causes emotional strain
• Causes deafness
• Increase the blood pressure

Question 8.
Write the ways to reduce sound pollution.
Answer:

• Ban the air horn
• Control loudspeakers
• Use silencers in vehicles
• Control the sound having more than 50 dB near the hospitals

Question 9.
Write two uses of ultrasonic sound.
Answer:
Use in SONAR
To find out the disease and treatment in medical field

Question 10.
Can we hear the sound from Galton whistle having a frequency of 30000Hz? Why?
Answer:
No. We cannot hear the sound having a frequency greater than 20000Hz

Question 11.
What are the problem faced by deaf people?
Answer:
The people having damage to hereby birth effect many difficulties for com¬munication, for ability to speak, vulnerability to danger, etc.

Question 12.
Complete the table.

No of vibrations	time	Frequency
10	….. a ….	2
15	3	…… b …..
……. c …..	5	4

Answer:
a. 5
b. 5
c. 20

Question 13.
An object vibrates 200 times in one second. What is its frequency?
Answer:
frequency = \(\frac{n}{t}=\frac{200}{1}=200 \mathrm{Hz}\)

Question 14.
How many times vibrate a body of frequency 290 Hz in 12 seconds.
Answer:
n = f × t
f = 290 Hz,
t = 12 s
n = 290 × 12 = 3480 times

Question 15.
Name the sounds of frequency below 20 Hz and above 20000 Hz.
Answer:
below 20 Hz = Infrasonic
Above 20000 Hz = ultrasonic

You can Download सफेद गुड़ Questions and Answers, Summary, Activity, Notes, Kerala Syllabus 8th Standard Hindi Solutions Unit 5 Chapter 1 help you to revise complete Syllabus and score more marks in your examinations.

Kerala State Syllabus 8th Standard Hindi Solutions Unit 5 Chapter 1 सफेद गुड़

सफेद गुड़ पाठ्यपुस्तक के प्रश्न और उत्तर

Safed Gud Story In Hindi Kerala Syllabus 8th प्रश्ना 1.
माँ के आसमान की ओर देखने का क्या कारण होगा?

उत्तर:
माँ चाहती होगी कि बेटे को पैसा दें। लेकिन वह विवश है। वह अपनी विवशता के कारण आकाश की ओर ताकती है। पैसे के अभाव में वह हमेशा ऐसा करती है। शायद वह ईश्वर से विनती करती होगी।

Safed Gud Kahani Ka Saransh Likho Kerala Syllabus 8th प्रश्ना 2.
वह अपने को धिक्कारने लगा और इस बुरे ख्याल के लिए ईश्वर से क्षमा माँगने लगा’ -यहाँ लड़के का कौन-सा मनोभाव प्रकट है?

उत्तर:
इससे बच्चे का विवेकशीलता प्रकट होता है। उसकी सच्चाई और गलती पर पछताने का भाव यहाँ स्पष्ट है।

Gud In Hindi Kerala Syllabus 8th प्रश्ना 3.
वह एक अठन्नी ही नहीं थी, उस गरीब पर ईश्वर की कृपा थी -ऐसा क्यों कहा है?

उत्तर:
वह पैसे के लिए बहुत तरसता था। बहुत प्रार्थना भी किया था। इसी अवसर पर उसे यह अठन्नी मिली। इसलिए उसे लगा कि वह ईश्वर की कृपा है।

सफेद गुड़ Textbook Activities

सफेद गुड कहानी का सारांश Kerala Syllabus 8th प्रश्ना 1.
निम्न्लिखित वाक्य पर घ्यान दें —

माँ बैठी फटे कपड़े सिल रही थी।

बताएँ, रेखांकित शब्दों में क्या संबंध है?

उत्तर:

Gud Meaning In Hindi Kerala Syllabus 8th प्रश्ना 4.
इस प्रकार आपसी संबंध रखनेवाले शब्द पाठ से चुनकर लिखें।

उत्तर:

Prarthana Poem In Hindi 8th Class Summary Kerala Syllabus 8th प्रश्ना 5.
लड़के की गुड़ खाने की इच्छा सफल नहीं हुई। उसके विचारों को डायरी के रूप में लिखें।

उत्तर:
25 जनवरी 2016
बहुत दिनों से गुड़ खाने की इच्छा थी। आज सोचा कि वह सफल हो गया। लेकिन क्या कहूँ, वह सपना सपना ही रह गया। नमक खरीदने बाज़ार जाते समय एक पैसे के लिए प्रार्थना करता रहा। ठीक उसी समय ज़मीन से एक अठन्नी पड़ी मिली। खुशी का ठिकाना न था। अफ़सोस है कि दुकानदार को देते समय वह हाथ से खिसक गया, धनिया के डिब्बे में। ढूँढ़ने से चिकना-सा पत्थर मिला। दुकानदार ने कहा कि मुफ्त में ले लो। लेकिन मन नहीं हुआ। नमक खरीद कर दुखी मन से वापस चला आया।

सफेद गुड़ Summary in Malayalam and Translation

सफेद गुड़ शब्दार्थ Word meanings

You can Download From Solitude Questions and Answers, Summary, Activity, Notes, Kerala Syllabus 8th Standard English Solutions Unit 5 Chapter 4  helps you to revise complete Syllabus and score more marks in your examinations.

Kerala State Syllabus 8th Standard Hindi Solutions Unit 5 Chapter 4 Solitude (Ella Wheeler Wilcox)

Solitude Textbook Questions And Answers

Solitude Poem Questions And Answers Kerala Syllabus 8th Question 1.
What does the opening lines tell us about the present-day world?

Answer:
In the present day world, people are only interested in sharing happiness and joy with others. Sorrows are to be faced all alone. This shows selfishness.

Solitude By Ella Wheeler Wilcox Questions And Answers Question 2.
’ Life is a mixture of joy and sorrow.’ How differently do people react to reach to each of them?

Answer:
There are many to share a person’s joy but none to comfort him/ her during his/her unhappy moments.

Solitude Poem Line By Line Explanation Kerala Syllabus 8th Question 3.
Even the earth is indifferent to human suffering. Identify lines that hint this idea.

Answer:
For the sad, old earth must borrow its mirth,

Summary Of The Poem Solitude Kerala Syllabus 8th Question 4.
‘Succeed and give and it helps you live. ‘Is this line an exhortation to help and support others in need?

Answer:
Yes, The poet means to suggest that success alone can motivate us to live and sharing the joy of our success can promote harmony.

8th English Notes Kerala Syllabus Kerala Syllabus Question 5.
Every human being must undergo pain as a part of life. Which lines give you this idea?

Answer:
‘But one by one we must all file on Through the narrow aisles of pain.’

Kerala Syllabus 8th Standard English Notes Question 6.
‘The poem throws light on the need to be ‘self-reliant’. Do you agree? Why?

Answer:
Yes, Being self-reliant helps us to overcome the problem of life and gives us confidence to face the challenges in life.’

Solitude Questions Answers Kerala Syllabus 8th Question 7.
Does the poem establish the idea that this is essentially a pleasure-seeking world? How?

Answer:
‘Yes, The world abides with us only when we are happy. Nobody will be there to share our sorrows.

My Sweet Solitude Meaning In Malayalam Kerala Syllabus 8th Question 8.
What does the poet mean by the expressions ‘nectared wine’ and ‘life’s gall’?

Answer:
Nectared wine: the happiest moment of her life. Life’s gall: the sorrows of one’s life.

Solitude Textbook Activities And Answers

Kerala Syllabus 8th Standard Notes English Question 1.
The theme of the poem is:
a. If you stay positive, you will become successful.
b. If you seclude yourself, you will have lots of friends.
c. If you weep, you weep alone.
d. If you stay positive, people will be with you.
Answer:
If you stay positive, people will be with you.

Kerala Syllabus 8th Standard English Solution Guide Question 2.
The tone of the poem is:
a. optimistic
b. pessimistic
c. indifferent
d. frustrated
Answer:
optimistic

Hss Live Guru 8th Standard English Kerala Syllabus Question 3.
Which line in the poem describes the speaker’s outlook on life?
a. ‘There is room in the halls of pleasure.’
b. ‘Rejoice, and men will seek you’.
c. The echoes bound to a joyful sound’.
d. For the sad old earth must borrow its mirth’.
Answer:
‘Rejoice, and men will seek you’.

Solitude Additional Questions and Answers

Read the lines from the poem ‘ Solitude’ and answer the questions that follow.
Laugh, and the world laughs with you,
Weep, and you weep alone;
For the sad old earth must borrow its mirth But has trouble enough of its own Sing, and the hills will answer;
Sigh, it is lost on the air
The echoes bound to a joyful sound;
But shrink from voicing care
1. What idea do we get from the opening lines?
2. Even the earth is indifferent to human suffering. Identify lines that hint this idea?
3. Life is a mixture of joy and sorrow. How differently do people react to reach each of them?
4. Pick out a word that means ‘ desire’.
Answer:
1. In the present day world, people are only interested in sharing happiness and joy with others. Sorrows are to be faced alone. This shows selfishness.
2. For the sad, old earth must borrow its mirth,
3. There are many to share a person’s joy but none to comfort him/ her during his/ her unhappy moments.
4. Mirth

Solitude Poem Line by Line Explanation Question 5.
Prepare a short profile on Ella Wheeler Wilcox using the hints given below.
Born: November 5, 1850
Famous as: American author and poet
Spouse: Rob ert Wilcox (1884)
Notable works: Solitude, Yesterday, Sweet Danger
Death: October 30, 1919, 68 years
Answer:
Ella Wheeler Wilcox:
Ella Wheeler Wilcox the famous author and poet was born on November 5, 1850. She married Robert Wilcox in the year 1884. Solitude, Yesterday and Sweet Danger are her notable works. She passed away on October 30, 1919, at the age of 68.

8th Class English Notes Kerala Syllabus Kerala Syllabus Question 6.
The following table shows the results gained by a school in the SSLC examination.
Read them carefully and answer the questions that follow.

Year	No attended	No passed	Percentage of pass
2006	98	32	32.6
2007	75	64	85-3
2008	103	90	87.5
2009	105	92	87.5
2010	103	90	87.4
2011	100	93	93

a. Which year did the highest number of students qualify for higher studies?
b. Identify the years in which equal number of students attended the examina¬tion?
c. What was the lowest percentage of pass recorded?
d. How many students appeared for exam in the year 2008?
e. Compare the results of the years 2006 and 2011.
Answer:
a. 2011
b.2008 and 2010
c. 32.6
d.103
e. In 2011 the pass percentage was 93 (Highest) and in 2006 the pass percentage was 32.6 (lowest).

Solitude Summary in English

This is a delightful little poem. The imagery is simple but it has layers of meaning and interconnections.Life is full of ups and downs and we can’t help but feel sad or happy at times. One day you feel like you are on top of the world and then the next you just want to be alone and you hate everyone. It is also full of unexpected twists because you’ll never know what life has for. Even if we are sad, we have to move on with life or we won’t feel like we are part of this world. The sad old earth must borrow its mirth .

It is just a poetic contrivance, but it seems to be saying that even the earth wouldn’t be interested in helping you to shoulder your burdens as it needs to gain strength only from the happiness of those who share its world. Even the last verse too is saying that ultimately you have to do something alone, no one can share your pain or your deathbed.

Solitude Summary in Malayalam

Solitude Glossary

You can Download Fibres and Plastics Questions and Answers, Summary, Activity, Notes, Kerala Syllabus 8th Standard Basic Science Solutions Chapter 17 help you to revise complete Syllabus and score more marks in your examinations.

Kerala State Syllabus 8th Standard Basic Science Solutions Chapter 17 Fibres and Plastics

We have variety of substances around us for improving our lifestyle. The natural resources are utilised to produce a variety of modern materials.

Fibres And Plastics Class 8 Kerala Syllabus Polymers

Cotton. Silk, jute, wool, rubber etc are the molecules belonging the group of polymers. Polymers are macromolecules formed by the combination of large number of simple molecules called monomers. Fibres are the polymers suitable for the manufacture of strong threads. Plastics are the polymers which can be moulded into different shapes. Rubber is an elastic polymer.

Manmade polymers

In order to overcome the demerits like less availability, less durability etc several synthetic polymers have been prepared through chemical methods. Synthetic threads have demerits too. Some of them are low aeration, low ability to absorb water, high inflammability etc

Basic Science Class 8 Chapter 17 Kerala Syllabus Plastic

These are the substances that changed the very face of human life which are having different properties.

Thermoplastics and thermosetting plastics

The plastic that gets softened on heating and hardened on cooling is thermoplastics. The plastic which remains soft when heated during its manufacture, and gets hardened permanently on cooling is thermosetting plastics.

Plastics and Pollution

Even though plastics are very useful substance, the careless use and misuse lead to environmental pollution. Plastics give many benefits to mankind. Forest conservation, household utility etc are some of the benefits. There are many ways to reduce pollution due to plastics. Some of them reduce the use of dispo¬sable plastics, reduce; the overuse of plastic materials, use other material like glass, ceramic materials instead of plastic etc.

Fibres and Plastics Textbook Questions and Answers

Basic Science For Class 8 Chapter 17 Kerala Syllabus Questions 1.
Polymers are macromolecules formed by the combination of many monomers.
a. How are polymers classified?
b. Classify the following:
Cotton, Wool, Nylon, Silk, Terylene, Jute, Polyester
Answer:
a. i. On the basis of its formation as natural and man-made.
ii. On the basis of structure as linear branches chain, cross-linked chain
iii. On the basis of process as addition polymer and condensation polymer.
iv. On the basis of molecular strength as fibres and plastics
b. Natural: wool, silk, jute, cotton Man-made: Nylon, Terylene, Polyester

Kerala Syllabus 8th Standard Physics Notes Questions 2.
Some monomers and polymers are given in the following table:

Monomer	Polymer
Ethene	Polyethene
Propene	Polypropene
Styrene Vinyl	Polystyrene
chloride	Polyvinyl chloride

a. What is meant by the terms ‘monomer’ and ‘polymer’?
b. What is the common system of nomenclature of polymers?
Analyse the table and find out.
Answer:
a. Monomer: A Simple molecule having a particular structure
Polymer: Macromolecules formed by combination of large number of monomers.
b. Add the word ‘poly’ before the name of monomer.

Kerala Syllabus 8th Standard Chemistry Notes Question 3.
Natural fibres and synthetic fibres are used in the field of textile manufacturing.
a. Compare their merits and demerits and tabulate.
b. Which of these clothes is most suited for the following situations? Give reason.
i. While cooking in the kitchen
ii. To wear during summer
Answer:
a. Merits:

• Comfortable to wear
• Not inflammable
• Ability to absorb water
• High aeration

Demerits:

• Less available
• Less durability
• Wrinkle easily
• Cannot dry easily on getting wet

b. Natural fibres:- Because they are not inflammable, have ability to absorb sweat, high aeration

8th Class Biology Notes Pdf Kerala Syllabus Question 4.
You know what thermoplastics and thermosetting plastics are.
a. Which of these plastics cannot be recycled?
b.You might have noticed that those who collect old plastics do not accept certain type of plastic articles. What are they? What may be the reason for this?
Answer:
a. Thermoplastic
b. Thermosetting plastic. Because they can’t be recycled.

Kerala Syllabus 8th Standard Biology Notes Question 5.
Some argue that plastics are to be completely banned as they cause environmental pollution. What is your view?
Answer:
No. Without plastic, we cannot manage daily life. Control the use of plastic. avoid disposable plastic products and use thermoplastic materials.

8th Class Biology Notes Pdf Malayalam Medium Question 6.
The school science club has N decided to conduct a poster propaganda for creating awareness about pollution due to plastics. Prepare some posters for this.
Answer:
Avoid disposable plastic products use glass, ceramic utensils or natural substances
Use paper or natural materials fo decorations
Don’t dump plastic materials in soil.

8th Standard Basic Science Textbook Kerala Syllabus Question 7.
What suggestions can you propose to realise the concept of ‘plastic waste-free school’? List your findings.
Answer:
Reduce: Buy only what you need because a better way to reduce waste is by not creating it.
Reuse: Instead of throwing out plastic product you no longer think you need, try repurposing them because plastics exist for long time. Eg: use refill in ball pens, use thick plastics which can be reused, reuse the plastic bottle. The banning of plastics below the thickness of 30 micron aims at this. When thickness increases a tendency will arise to use it again.

Recycling: Is the process by which the plastics which is rendered useless is heated and subjected to certain processes to produces new materials. Recycling the rate of environmental pollution

Refuse: We can avoid the use of plastic when it is not necessary. Avoid thin plastic covers when things are bought. Use cloth bag, paper bag or thick plastic covers which can be used for long time

Fibres and Plastics Additional Questions and Answers

8th Biology Notes Malayalam Medium Kerala Syllabus Question 1.
Differentiate between thermoplastic and thermosetting plastic.
Answer:
The plastic that gets softened on heating and hardened on cooling is thermoplastic. When heating physical change occurs.
The plastic which remains soft when heated and gets hardened permanently on cooling is thermosetting plastics. Chemical change occurs when heating.

Kerala Syllabus 8th Standard Biology Notes Malayalam Medium Question 2.
Given some occasions of using plastic. Find the peculiarity of plastic used and fill the table.
Answer:

Occasion	Peculiarity
As the covering of con­ductor
To make the handles of cooking vessels
To keep chemicals
To make water tanks
To make household materials

Answer:

Occasion	Peculiarity
As the. covering of conductor	Plastics are insulators
To make the hand­les of cooking vessels	Not conducting heat
To keep chemicals	Do not react with che­mical
To make water tanks	No rusting. Less weight
To make household materials	Easy to use. Less wei­ght

Kerala Syllabus 8th Standard Chemistry Notes Malayalam Medium Question 3.
Write 4 occasions which plastic is harmful to daily life.
Answer:

1. Environmental pollution when it is thrown without any control.
2. When burning it cause air pollution.
3. Hindrance in drainages
4. The water absorption property of soil decreases when plastics are dumped in soil.

Kerala Syllabus 8th Standard Notes Question 4.
What are the uses of plastic in the field of human health?
Answer:
To produce IV tubes, bottles To produce heart valves To produce packets

Synthetic Fibres And Plastics Class 8 Notes Kerala Syllabus Question 5.
What are the uses of plastic in the field of production of house building?
Answer:
To produce roof materials, doors, plumbing and wiring materials.

Class 8 Chemistry Notes Kerala Syllabus  Question 6.
List the peculiarities of plastic.
Answer:
Can mould in any shape, longlasting, insulator, do not conduct heats, not reacting with chemicals and water, will burn.

Question 7.
Separate natural and artificial polymer from the list
Rubber, wool, Pvc, Bakelite, nylon, rayon cellulose, silk, polythene, polyester
Answer:

Natural	Artificial
Rubber	P.V.C
Wool	Polythene
Cellulose	Nylon
Silk	Rayon
	Polyester

Question 8.
List the merits of natural and artificial polymer
Answer:

Merits	Demerits
Comfortable to wear	Less availability
More aeration Absorb	wrinkle easily
water, sweat Not	high cost not
easily burns	durable

Question 9.
If we heat polyethene cover can we convert into earlier stage? Justify.
Answer:
No. Undergoes chemical change because it is thermosetting plastic.

Question 10.
Filling in the blanks.
1. Natural polymer is ……………
2. Insulin is a ………….
3. is a monomer of polythene. …………..
4. Nylon is type of plastic. …………….
5. Bakelite is an example for plastic. …………..
6. Natural polymer which has elastic nature is ……………
7. Inflammable tendency is higher in …………….
8. Thermoplastic is a ……………. type polymer.
9. The constituent unit of polymer is called
10. Polymers of plant origin are made up of …………..
Answer:
1. Starch
2. Protein
3. Ethylene
4. thermoplastic
5. thermosetting
6. Rubber
7. Synthetic fibres.
8. linear
9. monomer
10. cellulose

Question 11.
Give examples for natural fibres.
Answer:
Coconut husk, cotton, hemp, silk etc.

Question 12.
What is vulcanization? What is the use of it?
Answer:
’The process of heating rubber with sulphur is called vulcanization. By vulcanization rubber retains its form and to increase the hardness, Moreover, tensile strength, elasticity keeping stability at high temperature etc. are increased.

Question 13.
Give four difference between natural rubber and synthetic rubber.
Answer:
1. Synthetic rubber is harder than natural rubber.
2. Natural rubber is easily flammable.
3. The elasticity of natural rubber is lower than that of synthetic rubber.
4. Synthetic rubber keeps stability at higher temperature.

Question 14.
Classify the following into thermoplastic and thermosetting plastics.
Bakelite, polyvinyl chloride, nylon, celluloid, urea-formaldehyde, Teflon, polyester, polythene.
Answer:

Thermoplastics	Thermosetting
Nylon	plastics
Polyvinyl chloride	Bakelite
polythene	urea formaldehyde
celluloid	polyester
	Teflon

Question 15.
Find out odd one and give reason. Bakelite, polyester, polythene, melamine formaldehyde.
Answer:
Polythene: All the others are thermosetting plastics.

You can Download We’re the World Questions and Answers, Summary, Activity, Notes, Kerala Syllabus 8th Standard English Solutions Unit 1 Chapter 4  helps you to revise complete Syllabus and score more marks in your examinations.

Kerala State Syllabus 8th Standard Hindi Solutions Unit 1 Chapter 4 We’re the World (Michael Jackson and Lionel Richie Jr.)

We’re the World Textbook Questions And Answers

We Are The World Questions Answers Kerala Syllabus 8th Question 1.
What, according to the lyricists, is the greatest gift of all?

Answer:
According to the lyricists, lending a hand to the life of others is the greatest gift of all.

We Are The World Poem Summary Kerala Syllabus 8th Question 2.
Why do you think that we can’t go on pretending forever?

Answer:
lt is useless to think that someone will soon make a change somewhere.

We’re The World 8th Standard Kerala Syllabus 8th Question 3.
‘It’s true we’ll make a better day Just you and me.’ How?

Answer:
When we work in perfect uaifion we can make the world a better place.

We Are The World Poem Lesson Plan Kerala Syllabus 8th Question 4.
When will a change really come according to the lyricists?

Answer:
According to lyrisicts a real change will come only when we stand together.

The World Poem Questions And Answers Kerala Syllabus 8th Question 5.
What might have prompted the lyricists to sing a song like this?

Answer:
The love for mankind and the suffering people around the world have prompted the lyricists to sing a song like this.

We’re the World Additional Questions & Answers

We’re The World 8th Standard Questions And Answers Question 1.
Read the lines from the song ‘ We’re the world’ and answer the questions that follow.
There comes a time when we heed a certain call
When the world must come together as one
There are people dying
And it’s time to lend a hand to life
The greatest gift of all
We can’t go on pretending day by day
That someone somewhere will soon make a change
We all are a part of God’s great big family
And the truth, you know,
Love is all we need
a. What is the greatest gift of all?
b. What do you understand by the expression ‘ lend a hand to life’?
c. Name the value that we all need?
d. What is the message of the poem?
Answer:
a. Lend a hand to life
b. To help others, people are dying
c. Love
d. Live in harmony

Hsslive Guru 8th Class English Kerala Syllabus Question 2.
Read the lines from the poem ‘We are the World’ and answer the question that follows.
There comes a time when we heed a certain call
When the world must come together
There are people dying
And it’s time to lend a hand to life
The greatest gift of all
We can’t go pretending day by day
That someone somewhere will soon make a change.
We are all part of God’s great big family.
And the truth you know;
Love is all we need.
We are the world, we are the children
So let’s start giving
There’s a choice we’re making
We’re saving our own lives
It’s true we’ll make a better day
Just you and me
Given below is the summary of the lines. Some words in it are miss¬ing. Choose suitable words from the lines given and complete it.
A time …(a)… when the world has to ..(b)…. the call and come…… (c) to help the ……. (d)…… people. We all belong to God’s …….. (e)……… and what we need is …..(f)….. for each other. We should not pretend someone somewhere will make a ……… (g) ……….. .
Answer:
a. comes
b. heed
c. together
d. dying
e. family
f. love
g. change

Hsslive Guru 8th English Kerala Syllabus Question 3.
Prepare a short profile of Michael Jackson using the hints given below.
Born: 1958, America
Known as: King of Pop
Famous as: Singer, Songwriter, Dancer, and Actor
Notable works: Bad, Dangerous, Off the wall, etc
Died Answer: 2009
Answer:
Michael Jackson:
Michael Jackson was born in 1958 in America. He was known as the King of Pop. He was famous as a singer, songwriter, dancer, and actor. His notable works are Bad, Dangerous, Off the Wall, etc. He passed away in 2009.

We’re the World Summary in English

There will be a time when all of us hear a ‘miner call’. Then the whole world will become one. The people go on dying. It is time for us to give a helping hand. It will be the best gift. Let us stop acting. Let us not think that someone will make a change somewhere. All of us are a part of the world. Love is the need. All of us know that truth.We are the world. We are the children.

We should make the world brighter. So we must start giving. Yes, we will make a good time indeed. Yourself and myself together. Give your hearts to the sad people. Then they will understand that we care for them. Thus their lives will become more strong. They will be free. Like God who changed the stones into bread, we will also do wonders in helping others. When you are completely distressed and helpless believe that there is no way for you to fall. Everything will be fine one day. We all should recognize that we must stay together for a complete change.

We’re the World Summary in Malayalam

We’re the World Glossary

You can Download For the Continuity of Generations Questions and Answers, Summary, Activity, Notes, Kerala Syllabus 8th Standard Basic Science Solutions Chapter 14 help you to revise complete Syllabus and score more marks in your examinations.

Kerala State Syllabus 8th Standard Basic Science Solutions Chapter 14 For the Continuity of Generations

For the Continuity of Generations Textbook Questions and Answers

For The Continuity Of Generations Biology Kerala Syllabus 8th Reproduction

In nature, there are various methods of reproduction to produce new generations.

For The Continuity Of Generations Kerala Syllabus 8th Budding

This is a method of asexual reproduction seen in Hydra, Yeast etc. The buds formed from the parent body detaches from it when mature and develop into a new organism.

Basic Science Class 8 Chapter 14 Kerala Syllabus Binary fission

Binary fission is seen in prokaryotes. Existing cell divides to form 2 new cells. In favorable conditions, bacteria-like organisms reproduce by binary fission

Kerala Syllabus 8th Standard Chemistry Notes Spore formation

This type of asexual reproduction is seen mainly in fungus. Spores are microscopic cells that can survive unfavourable conditions and develop into new organism on the return of favourable season.

Basic Science For Class 8 Chapter 14 Kerala Syllabus Pollination, Fertilization

Flowers are the sex organs in plants. Pollination is the process of transfer of pollen grains to the stigma of the flower. After pollination pollen tube grows towards the ovary. Simultaneously generative nucleus in the pollen grain divides at the pollen tube and two sperms are formed.
One of the sperms fuses with the ovum and forms the zygote. This process is called fertilization. The second sperm fuses with the polar nucleus in the ovary and forms the endosperm. Zygote develops into embryo and endosperm becomes the stored food for the growth of embryo.

Indicators (Text Book Page No:200)

Kerala Syllabus 8th Standard Chemistry Notes Malayalam Medium Questions 1.
Formation of male gametes
Answer:
After the pollination pollen tube grows towards the ovary. Simultaneously generative nucleus in the pollen grain divides at the pollen tube and two sperms are formed.

8th Class Biology Notes Pdf Malayalam Medium Questions 2.
Formation of embryo
Answer:
One of the sperms fuses with the ovum and forms the zygote. This process is called fertilization.

8th Class Biology Notes Pdf Kerala Syllabus Questions 3.
Formation of endosperm and its function
Answer:
The second sperm fuses with the polar nucleus in the ovary and forms the endosperm. Zygote develops into embryo and endosperm becomes the stored food for the growth of embryo.

8th Standard Chemistry Textbook Kerala Syllabus Male Reproductive system

The main parts of male reproductive system are Vas deferens, prostate gland, penis, testis etc.

Basic Science Class 8 Chapter 14 Solution Kerala Syllabus Vas deferens

Carries sperms from testis to urinary tract.

8th Standard Chemistry Textbook Kerala Syllabus Prostate gland

Secretes a fluid that contains factors required for the movement and nourishment of sperms.

Biology Class 8 Malayalam Medium Kerala Syllabus Penis

Deposits sperms into vagina

Basic Science Question Answer Chapter Wise Class 8 Testis

Produces sperms and male hormones.

Class 8 Science Notes Pdf State Syllabus  Sperm

Sperm is motile. It has a head, middle piece and tail. Mitochondria present in the middle piece provides energy for movement. In the head, nucleus containing paternal chromosomes are present.

Indicators (Text Book Page No:201)

Questions 4.
Characteristics of sperms
Answer:
Sperms:- Sperms are motile. It has a head, middle piece and tail. Mitochondria present in the middle piece provide energy for movement. In the head, nucleus containing paternal chromosomes is present.

Questions 5.
Location of testes and the production of sperms
Answer:
Testis are found in the scrotal sac outside abdominal cavity. Sperms are produced in the testis.

Questions 6.
Importance of glands
Answer:
Sperms reach the penis along with the fluid produced by accessory glands and they are secreted to outside. Secretions provide a medium for the movement of sperms and nourishment

Female Reproductive System

Ovaries, Oviduct, Uterus, Endometrium, Vagina, etc., are the parts of female reproductive system.
Ovary – Produces Ovum and female hormones.
Oviduct – Fertilization takes place in oviduct.
Uterus – Foetus completes its development in uterus.
Endometrium – Inner layer of Uterus. Foetus attach the endometrial wall.
Vagina – Uterus opens out through Vagina. Sperms are deposited here.

Ovum

Ovum is larger than sperms. They are non-motile. There are specified membranes outside the cell membrane of ovum.

Indicators (Text Book Page No:202)

Questions 7.
Characteristics of ovum
Answer:
Ovum is larger than sperms. They are non-motile. There are specified membranes outside the cell membrane of ovum.

Questions 8.
Function of ovary
Answer:
Produces ovum and female hormones.

Questions 9.
Completing the table (Text Book Page No:202)

Answer:

Characteristics	Sperm	ovum
Size	Microscopic cells	Larger than sperms
Movement (motility)	yes	No
Morpho logy	Parts like head, middle piece and tail are present	Specialized protective coverings Outside the Cell membrane

Menstruation

With the onset of ovulation, there are certain preparations in the uterus to facilitate embryonic development. Endometrium becomes thickened, and more capillary are formed. But if fertilization does not take place the newly formed tissues disintegrate and peel off from the uterine wall. These get eliminated to outside along with blood and mu¬cus through vagina. This process is called menstruation.

Fertilization

Fertilization is the process of fusion of ovum, that releases from the ovary with the sperm in the oviduct.

Placenta

It is the part that connects embryo with the endometrium. Oxygen and nutrients are supplied to the foetus through the umbilical cord formed from the placenta. Waste materials from the foetus are also eliminated through placenta.

Questions 10.
Completing the table (Text Book Page NO:204)

Answer:

Part	Function
Endometrium	Attachment of Embryo
Uterus	Complete development of foetus.
Placenta	Provides oxygen and nour­ishment to the foetus. Rem- oves wastes.
oves wastes.	Connects foetus with moth­er. Oxygen and nutrients are carried through um­bilical cord.
Amnion	Amniotic fluids inside am­nion present dehydration of focus and protects from external shocks

Indicators (Text Book Page No:206)

Question 11.
What is adolescence?
Answer:
Adolescence is the period between puberty and adulthood.

Question 12.
How does adolescence influence the physical and mental development of an individual?
Answer:
The characteristics of adolescence like brain development, rapid increase in the height and weight, growth of reproduction organs, increased efficiency of glands, etc., influence the physical and natural development of individuals.

Question 13.
Why is the rate of adolescence growth higher in girls than in boys?
Answer:
In girls, the parts of brain that control physical and mental changes develop fast.

Question 14.
Is there any need to be anxious about the physical changes during adolescence? Why?
Answer:
No Adolescence is only a stage in growth. Bodily changes are part of development into a fully mature organism.

Adolescence and Food

Indicators (Text Book Page No:206)

Question 15.
What is the circumstance that led to the supply of iron-folic acid tablets to students?
Answer:
In adolescence severe anemia, due to deficiency of Iron was reported.

Question 16.
What is the role of food habits to overcome this situation?
Answer:
Including leafy vegetables, eggs, amaranthus, liver, etc., in the diet will help to check diseases like anemia.

Question 17.
How should the food habits be regularised so as to ensure the availability of nutrients for the rapid growth of body in adolescence?
Answer:
Vegetables, leafy vegetables, milk, egg, cereals, pulses, etc., should be included in the diet.

Need for assertiveness

Question 18.
What is your response towards this statement?
Answer:
Agree

Question 19.
Can you cite such instances?
Answer:
Invitation to practice alcohol, drugs, sex abuse, etc., temptation to do the dont’s, instances of crimes, etc.

Question 20.
How will you respond if such instances occur in your life?
Answer:
Say ‘No’.

Let us assess (Text Book Page No:211)

Question 21.
Which of the following activities takes place after fertilization in plants?
A. Pollen tube grows
B. Egg is formed in the ovary
C. Ovule becomes the seed
D. Male gametes are formed
Answer:
C. Ovule becomes the seed

Question 22.
Which part helps in the transportation of materials without mixing maternal and foetal blood?
A. Endometrium
B. Uterus
C. Placenta
D. Amni
Answer:
C. Placenta

Question 23.
Sequentially arrange the process that takes place after pollination in plants.
1. Embryo is formed
2. Pollen tube grows
3. Fertilization takes place
4. Male gametes are formed
5. Zygote is formed
6. Generative nucleus divides
Answer:
1. Pollen tube grows
2. Generative nucleus divides
3. Sperms are formed
4. Fertilization takes place
5. Zygote is formed
6. Foetus is developed

Question 24.
Substantiate the statement: “Excessive likes and dislikes of food materials adversely affects the health”.
Answer:
Avoiding food in order to become slim causes many diseases like anorexia. Overeating causes obesity and other chronic diseases.

Question 25.
Home hygiene and social hygiene are as important as personal hygiene for health. Do you agree with this opinion of the doctor who led an awareness class on health? Why?
Answer:
Definitely, unhygienic environment helps in the proliferation of pathogens. The dangers caused by pollution is much dreaded. Therefore home hygienic and social hygiene are very important as personal hygiene.

Question 26.
“Adolescence is full of challenges and possibilities”.
a. What are the challenges faced by adolescents?
b. What are your suggestions to overcome these challenges?
Answer:

• Causes mental and emotional disturbances.
• Confusion about his/her role in the society.
• Poor understanding about hygiene, immaturity.
• Possibility to addiction to bad habits.
• To survive these challenges
• Practice to say ‘No’ to wrong ways
• Parents should take care to make the environment in home pleasant
• Be careful while choosing friends.
• Take part in social services.
• Participate in co-curricular activities in the school.

Question 27.
It is easy to be addicted to drugs. But to escape from it is not that easy.
a. What should be our approach towards drugs?
b. What are the harmful effects of drugs?
Answer:
Never use drugs in your life. A single-use may push us to its addiction.

Harmful Effects

• Disease that leads to cancer are caused.
• Loss of social recognition
• Breaks interpersonal relationships. Loss of peace in the family and distortion of family relationship.
• Financial crisis arise
• Possibility to indulge in crimes

For the Continuity of Generations Additional Questions & Answers

Question 28.
Prepare a short note on the mode of reproduction in the organisms mentioned below. (Hydra, Bacteria, Fungi)
Answer:
Hydra: reproduces by budding. Buds are formed on the parent body. When it grows it gets detached from the parent and develops into new organisms.
Bacteria: reproduces by binary fission. An existing cell divides to two new cells.
Fungi: reproduces by spore formation.

Question 29.
Night-blooming flowers are while and having intense fragrance why?
Answer:
The smell and color of flowers is to attract insects.

Question 30.
“The disappearance of certain plants caused the extinction of some insects”- substantiate this statement.
Answer:
Certain insects depend only specific plants for their food and reproductive purposes; especially butterflies. Hence their destruction way leads to the extinction of the dependant species.

Question 31.
What is the function of tube nucleus and generative nucleus?
Answer:
Generative nucleus divides to form sperms. Tube nucleus disintegrates.

Question 32.
How does endosperm form?
Answer:
The second sperm fuses with the polar nucleus in the ovary and forms the endosperm.

Question 33.
What is the fate of Zygote, endo spermete?
Answer:
Zygote develops into embryo and endosperm forms the stored food for the development of embryo.

Question 34.
Find out the parts of the male reproductive system that performs the following functions?
1. Secrets the fluid containing nutrients for sperms
2. Secretes male hormones.
3. Carries sperms from the testis to ureter.
Answer:
1. Prostate gland
2. Testis
3. Vas deferens

Question 35.
Arrange the following state¬ments under the headings sperm Ovum.
1. Nonmotile
2. Parts like head, middle piece and tail are present.
3. Nucleus is present in the head,
4. Mitochondria is in middle piece.
Answer:

Question 36.
Are Ovulation and menstruation the same process?
Answer:
No. Ovulation is the process of release of mature ovum from the ovary. If fertilization does not take place the newly formed tissues in the uterine wall peel off and come, out along with blood and mucus through vagina. This process is called menstruation.

Question 37.
Find the odd one. Write the reason.
Endometrium, androgen, Oes-trogen, progesterone.
Answer:
Endometrium – Inner layer of uterus. Others are hormones.

Question 38.
How does placenta form? What is its function?
Answer:
Placenta is formed of fetal tissues and uterine tissues. Oxygen and nutrients are supplied to the fetus and waste materials are eliminated through the umbilical cord formed from placenta.

Question 39.
Fill in the blanks
1. Mushrooms are plants that reproduce by means of
2. During favorable conditions amoeba reproduces by
3. In tapeworm, both the male and female sex organs are found in the same organism. So it is said to be a
4. Each in man contains about eight hundred or more long coiled, minute tubules called seminiferous tubules.
5. The intimate mechanical and
physiological connection between fetal and maternal tissue is provided by
6. A cord containing blood vessels which connect the placenta with the fetus is called.
7.0n an average the length of menstrual cycle in females is completed in days.
8. A person infected with AIDS loses his
9. Male gamete fuse with ovule to form
10. The period of sexual maturity in human beings called
Answer:
1. spores
2. binary fission
3. hermaphrodite
4. testis
5. placenta
6. umbilical cord
7. 28
8. immunity
9. zygote
10. puberty

Question 40.
What is ‘after-birth’?
Answer:
About 15 minutes after the delivery of the baby, the placenta detaches from the uterine wall and is expelled out as ’after-birth’.

Question 41.
The lungs of the foetus are filled with fluid so it cannot breathe. But it doesn’t feel breathlessness. Why?
Answer:
A special tissue develops between uterine wall and the embryo called placenta. The growing foetus gets nutrients and oxygen from the mother’s blood through the placenta and umbilical cord. So it doesn’t feel breathlessness.

Question 42.
How is the structure of sperms adapted for fertilization?
Answer:
The vibrating tail of sperm helps to reach up to to ovum. The mitochondria present in the sperm provides energy for this movement. The enzyme produced by the acrosome present on the head of the sperm helps the sperm nucleus in penetrating the sheath of the ovum and entering the. ovum.

You can Download Equal Triangles Questions and Answers, Activity, Notes, Kerala Syllabus 8th Standard Maths Solutions Chapter 9 help you to revise complete Syllabus and score more marks in your examinations.

Kerala State Syllabus 8th Standard Maths Solutions Chapter 9 Negative Numbers

Negative Numbers Text Book Questions and Answers

Textbook Page No 165

Negative Numbers Class 8 Kerala Syllabus Question 1.
Using the principles above, compute the following:
i. 5 – 10
ii. -10 + 5
iii. -5 – 10
iv. -5 – 5
vi. \(-\frac{1}{2}+1 \frac{1}{2}\)
vii. \(-\frac{1}{2}-1 \frac{1}{2}\)
viii. \(-\frac{1}{2}+\frac{1}{2}\)
Solution:
i. 5 – 10 = – (10 – 5) = -5
(since for x – y = -(y – x ))

ii. – 10 + 5 = 5 – 10 = – (10 – 5) = -5
(since for -x + y = y – x and x – y = – (y – x))

iii. -5 – 10 = – (5 + 10 ) = -15
(since for – x – y = -(x + y))

iv. -5 – 5 = – (5 + 5) = -10
(since for -x – y = -(x + y))

v. -5 + 5 = 5 – 5 = 0
(since for -x + y = y – x)

Kerala Syllabus 8th Standard Maths Notes Pdf Question 2.
Take as x different positive numbers, negative numbers and zero, and compute x + 1, x – 1, 1 – x. Check whether the equations below hold for all numbers.
i. (1 + x) + (1 – x) = 2
ii. x – (x – 1) = 1
iii. 1 – x = -(x – 1)
Solution:
If x = 1
x + 1 = 1 + 1 = 2
x – 1 = 1 – 1 = 0
1 – x = 1 – 1 = 0
If x = 2
x + 1 = 2 + 1 = 3
x – 1 = 2 – 1 = 1
1 – x = 1 – 2 – 1
If x = o
x + 1 = 0 + 1
x – 1 = 0 – 1 = -1
1 – x = 1 – 0 = 1
If x =-1
x + 1 = -1 + 1 = 1 – 1 = 0
x – 1 = -1 – 1 = -2
1 – x = 1 – (-1) = 1 + 1 = 2
If x = -2
x + 1 = -2 + 1 = -1
x – 1 = -2 – 1 = -3
1 – x = 1 – (-2) = 1 + 2 = 3

i. (1 + x) + (1 – x)
In x = 1, (1 + x) + (1 – x) = 2 + 0 = 2
In x = 2, (1 + x) + (1 – x) = 3 + (-1) = 3 – 1 = 2
In x = o, (1 + x) + (1 – x) = 1 + 1 = 2
In x = -1, (1 + x) + (1 – x) = 0 + 2 = 2
In x – 2, (1 + x) + (1 – x) – 1 + 3 = 3 – 1 = 2
(1 + x) + (1 – x) = 2 , for all values of x

ii. x – (x – 1)
In x = 1, x – (x – 1) = 1 – 0 = 1
In x = 2, x – (x – 1) = 2 – 1 = 1
In x = o, x – (x – 1) = 0 – (-1) = 1
In x = -1, x – (x – 1) = -1 – (-2) = -1 + 2 = 1
In x =-2, x – (x – 1) = -2 – (-3) = -2 + 3 = 1
x – (x – 1) = 1, for all values of x

iii. 1 – x
In x = 1, 1 – x = o = -(x – 1)
In x = 2, 1 – x = -1 = -(1) = -(x – 1)
In x = o, 1 – x = 1 = -(-1) = -(x – 1)
In x = -1, 1 – x = 2 = -(-2) = -(x – 1)
In x = -2, 1 – x = 3 = -(-3) = -(x – 1)
1 – x = -(x – 1), for all values of x

Hsslive Guru Maths 8th Standard Kerala Syllabus Question 3.
Taking different numbers as x, y and compute x + y, x – y. Check whether the following hold for all kinds of numbers.
i. (x + y) – x = y
ii. (x + y) – y = x
iii. (x – y) + y = x
Solution:
If we take x = 6 and y = 2, x + y = 6 + 2 = 8 and x – y = 6 – 2 = 4
If x = -6 and y = 2, x + y = -6 + 2 = -4 and x – y = -6 – 2 = -8
If x = 6 and y = -2, x + y = 6 + (-2) = 4
and x – y = 6 – (-2) = 8
If x = -6 and y = -2, x + y = (-6) + (-2)
= -8 and x – y = (-6) – (-2 ) = -4

i. (x + y) – x
If x = 6 and y = -2, (x + y) – x
= 8 – 6 = 2 = y
If x = -6 and y = 2, (x + y) – x
= -4 – (-6) = -4 + 6 = 2 = y
If x = 6 and y = -2, (x + y) – x
= 4 – 6 = – 2 = y
If x = -6 and y = -2, (x + y) – x
= -8 – (-6) = -8 + 6 = -2 = y
(x + y) – x = y, for all values of x and y

ii. (x + y) – y
If x = 6 and y = 2, (x + y) – y
= 8 – 2 = 6 = x
If x = -6 and y = 2, (x + y) – y
= -4 – 2 = -6 = x
If x = 6 and y = -2, (x + y) – y
= 4 – (-2) = 4 + 2 = 6 = x
If x = -6 and y = -2, (x + y) – y
= -8 – (-2) = -8 + 2 = -6 = x
(x + y) – y = x, for all values of x and y

iii. (x – y) + y
If x = 6 and y = 2, (x – y) + y
= 4 + 2 = 6 = x
If x = -6 and y = 2, (x – y) + y
= -8 + 2 = -6 = x
If x = 6 and y = -2, (x – y) + y
= 8 + (-2) = 8 – 2 = 6 = x
If x = -6 and y =- 2, (x – y) + y
= -4 + (-2) = -6 = x
(x – y) + y = x, for all values of x and y

8th Standard Maths Notes Kerala Syllabus Question 4.
Check whether the equation are identities. Write the patterns got from each, on taking x = 1, 2, 3, 4, 5 and x = -1, -2, -3, -4, -5.
i. -x + (x + 1) = 1
ii. -x + (x + 1) + (x + 2) – (x + 3) = o
iii. -x – (x + 1) + (x + 2) + (x + 3) = 4
Solution:
i) -x + (x + 1) = 1
If x = 1, -x + (x + 1)
= -1 + (1 + 1) = -1 + 2 = 1
If x = 2, -x + (x + 1)
= -2 + (2 + 1) = -2 + 3 = 1
If x = 3, -x + (x + 1)
= -3 + (3 + 1) = -3 + 4 = 1
If x = 4 -x + (x + 1)
= 4 + (4 + 1) = -4 + 5 = 1
If x = 5, -x + (x + 1)
= -5 + (5 + 1) = -5 + 6 = 1
If x = -1, -x + (x + 1)
= -(-1) + (-1 + 1) = 1 +0 = 1
If x = -2, -x + (x + 1)
= -(-2) + (-2 + 1) = 2 + (-1) = 1
If x = -3, -x + (x + 1)
= -(-3) + (-3 + 1) = 3 + (-2) = 1
If x = -4, -x + (x + 1)
= -(-4) + (-4 + 1) = 4 + (-3) = 1
If x = -5, -x + (x + 1)
= -(-5) + (-5 + 1) = 5 + (-4) = 1
It is an identity.

ii. -x + (x + 1) + (x + 2) – (x + 3) = 0
If x = 1, -x + (x + 1) + (x + 2) – (x + 3)
= -1 + (1 + 1) + (1 + 2) – (1 + 3)
= -1 + 2 + 3 – 4 = 0
If x = 2, -x + (x + 1) + (x + 2) – (x + 3)
= -2 + (2 + 1) + (2 + 2) – (2 + 3)
= -2 + 3 + 4 – 5 = 0
If x = 3, -x + (x + 1) + (x + 2) – (x + 3)
= -3 + (3 + 1) + (3 + 2) – (3 + 3)
= -3 + 4 + 5 – 6 = o
If x = 4 -x + (x + 1) + (x + 2) – (x + 3)
= -4 + (4 + 1) + (4 + 2) – (4 + 3)
= -4 + 5 + 6 – 7 = 0
If x = 5, -x + (x + 1) + (x + 2) – (x + 3)
= -5 + (5 + 1) + (5 + 2) – (5 + 3)
= -5 +6 +7 -8= 0
If x = -1, -x + (x + 1) + (x + 2) – (x + 3)
= -(-1) + (-1 + 1) + (-1 + 2) – (-1 + 3)
= 1 + 0 + 1 – 2 = 0
If x = -2, -x + (x + 1) + (x + 2) – (x + 3)
= 2 + (-2 + 1) + (-2 + 2) – (-2 + 3)
= 2 + -1 + 0 – 1 = 0
If x = -3, -x + (x + 1) + (x + 2) – (x + 3)
= 3 + (-3 + 1) + (-3 + 2) – (-3 + 3)
= 3 + -2 + -1 – 0 = 0
If x = -4, -x + (x + 1) + (x + 2) – (x + 3)
= 4 + (-4 + 1) + (-4 + 2) – (-4 + 3)
= 4 + -3 + -2 – (-1) = 0
If x = -5, -x + (x + 1) + (x + 2) – (x + 3)
= 5 + (-5 + 1) +(-5 + 2) – (-5 + 3)
= 5 + -4 + -3 – (-2) = o
It is an identity.

iii. -x – (x + 1) + (x + 2) + (x + 3) = 4
If x = 1, -x – (x +1) + (x + 2) + (x + 3)
= -1 – (1 + 1) + (1 + 2) + (1 + 3)
= -1 – 2 + 3 + 4 = 4
If x = 2, -x – (x + 1) + (x + 2) + (x + 3)
= -2 – (2 + 1) +(2 + 2) + (2 + 3)
= -2 – 3 + 4 + 5 = 4
If x = 3, -x – (x + 1) + (x + 2) + (x + 3)
= -3 – (3 + 1) + (3 + 2) + (2 + 3)
= -3 – 4 + 5 + 6 = 4
If x = 4 -x – (x + 1) + (x + 2) + (x + 3)
= -4 – (4 + 1) + (4 + 2) + (4 + 3)
= -4 – 5 + 6 + 7 = 4
If x = 5, -x – (x + 1) + (x + 2) + (x + 3)
= -5 – (5 + 1) + (5 + 2) +(5 + 3)
= -5 – 6 + 7 + 8 = 4
If x = -1, -x – (x + 1) + (x + 2) + (x + 3)
= -(-1) – (-1 + 1) + (-1 + 2) + (-1 + 3)
= 1 – 0 + 1 + 2 = 4
If x = -2, -x – (x + 1) + (x + 2) + (x + 3)
= 2 – (-2 + 1) + (-2 + 2) + (-2 + 3)
= 2 – (-1) + 0 + 1 = 4
If x = -3, -x – (x + 1) + (x + 2) + (x + 3)
= 3 – (-3 + 1) + (-3 + 2) + (-3 + 3)
= 3 – (-2) + – 1 + 0 = 4
If x = -4, -x – (x + 1) + (x + 2) + (x + 3)
= 4 – (-4 + 1) + (-4 + 2) + (-4 + 3)
= 4 – (-3) + – 2 + (-1) = 4
If x = -5, -x – (x + 1) + (x + 2) + (x + 3)
= 5 – (-5 + 1) + (-5 + 2) + (-5 + 3)
= 5 – (-4) + -3 + (-2) = 4
It is an identity.

Kerala Syllabus 8th Standard Maths Notes Question 5.
Taking different numbers, positive, negative and zero, as x, y, z and compute x + (y + z) and (x + y) + z. Check whether the equation, x + (y + z) = (x + y) + z holds for all these numbers.
Solution:

Textbook Page No 178

Class 8 Maths Kerala Syllabus Question 6.
Take various positive and negative numbers as x, y, z and compute (x + y) z and xz + yz. Check whether the equation (x + y) z = xz + yz holds for all these.
Solution:

Kerala Syllabus 8th Standard Maths Guide Question 7.
In each of the following equations, take x as the given numbers and compute the numbers y.
i. y = x², x = -5, x = 5
ii. y = x² + 3x + 2, x = -2
iii. y =x² + 5x + 4, x = -2, x = -3
iv. y = x³ + 1, x = -1
v. y = x³ + x² + x + 1
Solution:
i. y = x² , x = -5 , x = 5
If x =-5, y = x² = (-5 )² = -5 × -5 = 25
If x = 5, y = x² = (5)² = 5 × 5 = 25

ii. y = x² + 3x + 2, x = -2
If x = -2, y = x² + 3x + 2 = (-2)² + 3x(-2) + 2
= 4 – 6 + 2 = -2 + 2 = 0

iii. y = x² + 5x + 4, x = -2 , x = -3
If x = -2, y = x² + 5x + 4 = (-2 )² + 5x(-2) + 4
= 4 – 10 + 4 = -6 + 4 = -2
If x = -3, y = x² + 5x + 4 = (-3)² + 5x(-3) + 4
= 9 – 15 + 4 = -6 + 4 = -2

iv. y = x³ + 1, x = -1
If x = -1, y = x³ + 1 = (-1 )³ + 1
= (-1)(-1)(-1) + 1 = 1 × (-1) + 1 = 0

v. y = x³ + x² + x + 1, x = -1
If x = -1, y = x³ + x² + x + 1 = (-1)³ +(-1)² + (-1) + 1 = -1 + 1 – 1 + 1 = o

Kerala Syllabus 8th Standard Maths Question 8.
For a point starting at a point P and travelling along a straight line, time of travel is taken as t and the distance from P as s. The relation between s and t is found to be s = 12t – 2t², where distances to the right are taken as positive numbers and to the left as negative numbers.
i. Is the position of the point to the right or left of P, till 6 seconds?
ii. Where is the position at 6 seconds?
iii. After 6 seconds?
(Here it is convenient to write 12t – 2t² = 2t(6 – t).
Solution:
i. S = 12t – 2t²
Distance to the point when time is 1 second = 12t – 2t² = 12 × 1 – 2 × 1² = 12 – 2 = 10 m
Distance to the point when time is 5 second = 12t – 2t² = 12 × 5 – 2 × 5² = 60 – 50 = 10 m
Since the distance to the point till 6 seconds is positive. So the position of the point is on the right of P.
ii. Distance to the point when time is 6 second = 12t – 2t² = 12 × 6 – 2 × 62 = 72 – 72 = o
At the 6^th second, the point is at P.
iii. Distance to the point when time is 7 second (after 6 sec)= 12t – 2t² = 12 × 7 – 2 × 7²
= 84 – 2 × 49 = 84 – 98 = -14 metres
This is a negative number, So the position of the point is on the left of P.

Textbook Page No 179

8th Std Maths Guide Kerala Syllabus Question 9.
Natural numbers, their negatives and zero are together called integers. How many pair of integers are there, satisfying the equation. x² + y² = 25?
Solution:
It is convenient to write it as a table

Textbook Page No 180

Kerala Syllabus 8th Standard Maths Notes Malayalam Medium Question 10.

Solution:

Class 8 Kerala Syllabus Maths Question 11.

Solution:

Class 8 Maths Scert Solutions Kerala Syllabus Question 12.
In the equation \(z=\frac{x}{y}-\frac{y}{x}\), take x as the numbers given below and calculate the number z.
i. x = 10, y = -5
ii. x = -10, y = 5
iii. x = -10, y = -5
iv. x = 5, y = -10
v. x = -5, y = 10
Solution:

Additional Questions and Answers

Maths Class 8 Kerala Syllabus  Question 1.
Match the following

Solution:

8th Class Maths Notes Kerala Syllabus Question 2.

Solution:

Question 3.
Which of the following number is the largest (-1)⁶, (-1)¹⁰, (-1)², (-1)⁵⁰
Solution:
If the power of (-1) is even then answer will be 1
If the power of (-1) is odd then answer will be -1
(-1)⁶ = 1
(-1)¹⁰ = 1
(1)² = 1
(-1)⁵⁰ = 1
All the given numbers are equal.

Question 4.

Solution:

Question 5.
Complete the following table

Solution:

Question 6.
Write whether the answer got on doing the following operations are positive number or negative number.

Solution:

Question 7.

Solution:

Question 8.

Solution:

Question 9.
Calculate (-1)¹⁰ + (-1)¹⁷ + (-1)²¹ + (-1)²⁶ + (-1)⁷⁷
Solution:
(-1)¹⁰ + (-1)¹⁷ + (-1)²¹ + (-1)²⁶ + (-1)⁷⁷
= 1 + (-1) + (-1) + 1 + (-1)
= 1 – 1 – 1 + 1 – 1 = 2 – 3 = -1

Question 10.
Simplify [(-4) × (-5)] + [-16 × \(\frac{-1}{2}\) ]
Solution:
-4 × -5 = 20

Question 11.
If x = 8 and y = -3; find the values of x + y, y + x, x – y, y – x, -x – y and – y – x
Solution:
x + y = 8 + -3 = 5
y + x = -3 + 8 = 5
x – y = 8 – (-3) = 8 + 3 = 11
y – x = -3 – 8 = -11
– x – y = -8 – (-3) = -8 + 3 = -5
-y – x = -(-3) – 8 = 3 – 8 = -5

Question 12.
If x = 7, y = -6 and z = -2, find the value of
i. (x + y) + z
ii. x + (y + z)
iii. xyz
iv. (x + y)z
v. xy + xz
Solution:
i. (x + y) + z = (7 + -6) + -2 = 1 – 2 = -1
ii. x + (y + z) = 7 + (-6 + -2)
= 7 – 8 = -1
iii. xyz = 7 × -6 × -2 = 84
iv. (x + y)z = (7 + -6) × -2
= 1 × -2 = -2
v. xy + xz = (7 × -6) + (7 × -2)
= -42 – 14
= -56

Question 13.
Compute y = x² + 9x – 5, for take x as the given number,
i. x = 5
ii. x = -2
iii. x = o
iv. x = -3
Solution:
i. x = 5
y = x² + 9x – 5
= 5² + 9 × 5 – 5 = 25 + 45 – 5
= 20 + 45 = 65

ii. x = -2
y = x² + 9x – 5
=(2)² + 9 × (-2) -5
= 4 – 18 – 5 = 4 – 23 = – 19

iii. x = 0
y = x² + 9x – 5
= 0 + 9 × 0 – 5 = -5

iv. x = -3
y = x² + 9x – 5
= (-3)² + 9 × (-3) – 5
= 9 – 27 – 5 = 9 – 32 = -23

Question 14.
Find y = x⁴ + x³ + x² + x + 1, If x = -1
Solution:
y = x⁴ + x³ + x² + x + 1
= (-1)⁴ + (-1)³ + (-1)² + (-1) + 1
= 1 + (-1) + 1 + (-1) + 1
= 1 – 1 + 1 – 1 + 1
= 0 + 0 + 1 = 1

Question 15.
Complete the table

Solution: