Class 8

You can Download इस बारिश में Questions and Answers, Summary, Activity, Notes, Kerala Syllabus 8th Standard Hindi Solutions Unit 4 Chapter 2 help you to revise complete Syllabus and score more marks in your examinations.

Kerala State Syllabus 8th Standard Hindi Solutions Unit 4 Chapter 2 इस बारिश में

इस बारिश में पाठ्यपुस्तक के प्रश्न और उत्तर

इस बारिश में कविता Kerala Syllabus 8th Chapter 2 प्रश्ना 1.
‘उसी के पास अब मेरी / बारिश भी चली गई’ से आपने क्या समझा?

उत्तर:
यह एक किसान का रोदन है। यह रोदन किसान की हालत की ओर संकेत करता – है। आजकल किसानों की ज़मीन छीन ली जाती है। यहाँ किसान यह व्यक्त करता है कि ज़मीन के साथ बारिश भी चली गई है। यहाँ खेती और बारिश के घने संबंध स्पष्ट होते हैं।

Is Barish Mein Kerala Syllabus 8th Chapter 2 प्रश्ना 2.
जिसकी नहीं कोई ज़मीन/उसका नहीं कोई आसमान’ इन पंक्तियों का क्या तात्पर्य है?

उत्तर:
इन पंक्तियों का मतलब है कि किसानों का ज़मीन से अटूट संबंध है। ज़मीन नष्ट होने पर किसान का अस्तित्व नष्ट हो जाता है। यह उस से जीने के सब सपने नष्ट हो जाते हैं।

इस बारिश में Textbook Activities

इस बारिश में कविता Meaning In Malayalam Chapter 2 प्रश्ना 1.
कविता में ‘उसी के लिए’ दोहराया गया है। यह प्रयोग किन-किन की ओर संकेत करता है?

उत्तर:
किसानों का शोषण करनेवालों की ओर यहाँ संकेत है।

इस बारिश में कविता का सारांश Kerala Syllabus 8th Chapter 2 प्रश्ना 2.
‘हल नहीं / बैल नहीं’ -इसमें ‘हल’ और ‘बैल’ किन-किनके प्रतीक हैं?

उत्तर:
हल’ और ‘बैल’ खेती और किसानी ज़िंदगी के प्रतीक हैं।

Hss Live Guru 8 Hindi Kerala Syllabus Chapter 2  प्रश्ना 3.
निम्नलिखित आशयवाली पंक्तियाँ चुनकर लिखें।

फसल होने पर कर्ज चुकाने की किसान की झूठी प्रतीक्षा भी नहीं रह गई।

उत्तर:
अगली फसल होते ही सब चुकता कर दूंगा/अब तो मेरी झूठी/ये गुज़ारिश भी चली गई।

Hss Live Guru 8th Hindi Kerala Syllabus Chapter 2 प्रश्ना 4.
आस्वादन टिप्पणी तैयार करें।

उत्तर:
नरेश सक्सेना समकालीन हिंदी कविता के समर्पित कार्यकर्ताओं की अग्रिम पंक्ति में हैं। ‘इस बारिश में’ नामक कविता में किसान की ज़मीन छीन जाने की कथा है। यह एक किसान का बारिश के मौसम का शोकगीत है। आकाश में कई दूर छा जानेवाले बादलों को देखकर किसान आह भरता है। अपनी ज़मीन छिन जाने पर किसान खेती न कर सकता। भूमंडलीकरण के दौर के किसानों की सिसकियाँ यहाँ हम देख सकते हैं। इस कविता क द्वारा कवि किसान लोगों की त्रासदी की ओर हमारा ध्यान आकर्षित करते हैं। कवि का कहना है कि अब बारिश भी ज़मीन के पीछे चली गई है। धरती की छाती से सौंधी सुगंध भी छिन गई मिट्टी के लिए उठती है।

अब किसान के लिए हल और बैल नहीं, खेतों के बीच का रास्ता नहीं, कहीं हरियाली की बूंद भी दिखाई न देता। किसान के जीवन का ताल, प्रतीक्षा का नक्षत्र सब नष्ट हो चुकी है। फसल होने पर कर्ज चुकाने की किसान की प्रतीक्षा भी नहीं रह गई। किसान की अपनी खेत – खलिहानों से दूर रहने की विवशत इस कविता में हम देख सकते हैं। ज़मीन छिन जाने पर किसान भयानक शोषण का शिकार बन जाता है। कवि . इस कविता दवारा यही कहना चाहता है। एक कविता तभी समसामयिक मानी जाती है जब वह तत्कालीन समस्याओं का
संबोधन करती है। इस बारिश में’ नामक यह कविता इस कसौटी पर खरा उतरता है।

इस बारिश में Summary in Malayalam and Translation

इस बारिश में शब्दार्थ Word meanings

You can Download Reflection of Light in Spherical Mirrors Questions and Answers, Summary, Activity, Notes, Kerala Syllabus 8th Standard Basic Science Solutions Chapter 18 help you to revise complete Syllabus and score more marks in your examinations.

Kerala State Syllabus 8th Standard Basic Science Solutions Chapter 18 Reflection of Light in Spherical Mirrors

The phenomena of light is always a surprising one. From long time ago man has tried to study about light. This chapter explains to draw the figure of the images formed by mirrors, their uses, magnification etc.

Reflection Of Light In Spherical Mirrors Class 8 Notes Spherical mirrors

Images are formed not only in-plane mirrors but also in smooth curved surfaces. Spherical mirrors are mirrors in which the reflecting surface is a part of the sphere. The center of a sphere of which the mirror is a part is the center of curvature. Any I line drawn from the center of curvature to the mirror is normal to the mirror. Radius of curvature of a mirror is the radius of the sphere of which is a part. The reflecting surface of the mirror is called the aperture of a mirror. The midpoint of the reflecting surface is called the pole. The straight line connecting the pole and center of curvature of a mirror is the principal axis of the mirror.

The angle of incident and angle of reflection are equal in spherical mirrors. Rays of light incident on a concave mirror, parallel to the principal axis, passes through a fixed point on the principal axis after reflection. This point is the principal focus of the concave mirror. Rays of light incident on a convex mirror parallel to the principal axis appear to come from a fixed point on the other side of the mirror. The point is the principal axis of the convex mirror.

Focal length of a mirror is the distance from pole of the mirror and the principal’s focus of the mirror. Rays of light coming from infinity get focused on a plane perpendicular to the principal axis. This plane is the focus plane. The focus plane passes through the focus plane.

Reflection Of Light In Spherical Mirrors Class 8 Images formed by spherical mirrors

The image of an object placed different positions in front of a mirror is.formed in different positions. Rays of light incident on a concave mirror, parallel to the principal axis, passes through a fixed point on the principal axis after reflection Rays incident on an a concave mirror through the principal focus are reflected parallel to the principal axis.

Rays incident through the center of curvature reflected through the same path. Rays incident on the pole makes an angle with the principal axis. The ray diagrams of images formed by spherical mirrors are drawn according to the above rules. An object placed between F and C in front of a concave mirror, the image will be real and inverted. If the object is at F the image is formed at infinity. The paths of reflected rays are parallel to each other. If the object is in between F and P the image is formed behind the mirror. The image is erect and virtual.

Reflection Of Light In Spherical Mirrors 8th Magnification

Magnification is the ratio of the height of the image to the height of the object.

Reflection Of Light In Spherical Mirrors Class 8 Notes Pdf Uses of spherical mirrors

Spherical mirrors are used in lighthouses and reflectors.

Reflection of Light in Spherical Mirrors Textbook Questions and Answers

Class 8 Physics Notes Kerala Syllabus Questions 1.
Classify the following statements as to those related to concave mirrors and convex mirrors and tabulate them accordingly.
a. to view the face
b. as makeup mirror
c. as rearview mirrors in vehicles
d. in solar concentrators
e. in periscopes
f. as shaving mirror
Answer:
Concave mirror:

• In solar concentrators
• Makeup mirror
• Shaving mirror

Convex mirror:

• In rearview mirrors of vehicles
• In Searchlights

Plane mirror:

• In periscopes
• To see face

8th Class Physics Notes Pdf Question 2.
Calculate the radius of curvature of a convex mirror of focal length 12 cm.
Answer:
focal length of the mirror = 12 cm
\(\mathrm{f}=\frac{\mathrm{R}}{2} \quad 12=\frac{\mathrm{R}}{2}\)
R = 2 × 12 = 24 cm

Reflection Of Light At Curved Surfaces Questions And Answers 8th Question 3.
A ray of light is made to fall on the pole of a concave mirror making an angle 30° with the principal axis.
a. What is the angle of reflection?
b. Justify your answer.
c. Draw the ray diagram.
Answer:
a. Angle of reflection is 30°
b. angle of incidence and angle of reflection are equal
c. the figure showing angle of incidence and angle of reflection is 210°

Chemistry Class 8 Kerala Syllabus Question 4.
Which type of mirror always gives an erect and diminished image?
Answer:
Convex mirror

Kerala Syllabus 8th Standard Chemistry Notes Question 5.
A ray of light incident on a spherical mirror gets reflected along the same path. If so, show the light incident on the mirror.
Answer:

8th Class Biology Notes Pdf Question 6.
OA is a ray of light incident on a concave mirror.
a. Draw the path of the reflected ray

b. On what basis did you mark the reflected ray?
Answer:

b. In mirrors angle of incidence and angle of reflection are same. The normal to the point of incidence is passed through the center of curva¬ture. The angle between ray of reflection and the normal is the same as angle of incidence.

8th Class Biology Notes Pdf Malayalam Medium Question 7.
Write down the type of mirrors that should be used for getting the following type of images.
a. real and magnified
b. virtual and magnified
c. virtual and diminished
d. real and diminished
Answer:
a. concave mirror
b. concave mirror
c. convex mirror
d. concave mirror

Kerala Syllabus 8th Standard Chemistry Notes Malayalam Medium Question 8.
The height of an object kept 12 cm away from a concave mirror is 1 cm. Calculate the magnifica¬tion if an image of height 2.5 cm is formed in front of the mirror.
Answer:

8th Standard Chemistry Textbook Question 9.
Which type of mirror always gives a virtual and erect-image, b. Is this image magnified or diminished?
Answer:
a. convex mirror
b. Diminished

Reflection of Light in Spherical Mirrors Additional Questions and Answers

8th Class Biology Notes Pdf Kerala Syllabus Question 1.
Complete the table

No	Angle of incidence	Angle of reflection
1	30°	…… (a) …….
2	…. (b)…	40°
3	50°	…. (c)…
4	60°	… (d) ….

Answer:
a. 30°
b. 40°
c. 50°
d. 60°

Kerala Syllabus 8th Standard Physics Notes Question 2.
If the radius of curvature of a concave mirror is 24 cm what is its focal length?
Answer:
R = 24 cm

8th Standard Chemistry Textbook Kerala Syllabus Question 3.
Find the radius of curvature of a convex mirror of focal length 0.6 m
Answer:

Basic Science Class 8 Solutions Question 4.
Write the characteristics of the image formed by an object plac¬ed at the center of curvature of a concave mirror?
Answer:
Position: At the center of curvature at the same side
Size : Same as the size of the object Nature: Real, Inverted

Reflection Of Light By Spherical Mirrors 8th Question 5.
Complete the figure

Answer:

Hsslive Guru Physics 8th Standard Question 6.
Complete the table

Answer:
a. Passes through principal focus
b. Seem to come from the principal focus
c, d. Returns parallel to the principal axis
e, f. Returns through the same path
g, h. Reflects in the same angle of incident ray.

Question 7.
Write three differences of real image and virtual image which is made by spherical mirrors
Answer:
Real image:

1. Inverted
2. can be shown on the screen
3. can measure the length of the image and distance to the image

Virtual image:

1. Cannot show on the screen
2. Cannot measure
3. Erect

Question 8.
Write uses of concave mirrors
Answer:

•  As shaving mirror
• As makeup mirror
• As head mirrors used by doctors
• In film projectors

Question 9.
Examine the position off the object given in the figure and table the following peculiarities

a. position of the image
b. size of the image
c. nature of the image
Answer:
a. Behind the mirror.
b. Larger than the object.
c. Erect and virtual

Question 10.
When an object of height 4 cm is placed in front of a concave mirror an image of height 8cm is formed. Find magnification.
Answer:
h_i = 4cm h_o= -8 cm
Magnification = \(\frac{h_{i}}{h_{0}}\) = \(\frac{h_{-8}}{h_{4}}\) = -2

Question 11.

a. Examine the figure and find the magnification
b. What is the height of the object if height of the image is 4cm when the object is placed on the same position in front of the mirror.
Answer:

Question 12.
Write the uses of convex mirror
Answer:

• As reflector in the street light
• As rearview mirror
• In searchlights

You can Download From My Grandmother’s House Questions and Answers, Summary, Activity, Notes, Kerala Syllabus 8th Standard English Solutions Unit 5 Chapter 3  helps you to revise complete Syllabus and score more marks in your examinations.

Kerala State Syllabus 8th Standard Hindi Solutions Unit 4 Chapter 3 My Grandmother’s House (Kamala Das)

My Grandmother’s House Textbook Questions And Answers

My Grandmother’s House Questions And Answers Kerala Syllabus 8th Question
1. ……… ‘That woman died, ……… ’Who is the woman referred to here? How is she related to the poet?
Answer:
Grandmother

My Grandmother’s House Poem Questions And Answers Kerala Syllabus 8th Question 2.
What happened to the house after the death of the grandmother?
Answer:
After her death, the house withdrew into silence and snakes moved among the books.

My Grandmother’s House Poem Question And Answers Kerala Syllabus 8th Question 3.
’………. to lie Behind my bedroom door like a brooding Dog…. means that
i. The memories will always remain with the poet.
ii. The memories will lie unca-red for in a corner.
iii. The memories are as important as a dog.
Answer:
The memories will always remain with the poet.

My Grandmother House Question Answer Kerala Syllabus 8th Question 4.
The poet wants to go back to the house
i. to peer ……………
ii. to listen ………………
iii. to pick …………..
Answer:
5. Identify the most appropriate meaning for the expression, ‘an armful of darkness’.
i. Sad days
ii. Darkness of the past
iii. Memories of the grandmother’s house.
Answer:
memories of the grandmother’s house.

My Grandmother’s House Questions And Answers Pdf Kerala Syllabus 8th Question 6.
In the last three lines of the poem, the poet thinks of herself as a beggar.
a. What is she begging for?
b. What does she mean by sma- II change’?
Answer:
a. She is begging for love,
b. small quantity

My Grandmother’s House Question Answer Kerala Syllabus 8th Question 7.
Why are the eyes of the windows described as blind?
Answer:
Windows are dusty and so one cannot see through it.

Question Answers Of The Poem My Grandmother’s House Kerala Syllabus 8th  Question 8.
The air in the grandmother’s house is frozen. Why?
Answer:
Due to silence and loneliness

My Grandmother’s House Figure Of Speech Kerala Syllabus 8th Question 9.
Which words tell you that the poet is talking to someone? What is she talking about?
Answer:
The word ‘darling’. She is talking about the house that she had lived in and the love she received while living there.

My Grandmother Poem Questions And Answers Kerala Syllabus 8th Question 10.
How does the house itself share the grief of grandmother’s death?
Answer:
The house withdrew into silence and snakes moved among the books.

My Grandmother’s House Textbook Questions And Answers

Let’s revisit

8th Standard English Notes Kerala Syllabus Activity 1.

The poet thinks of her past. How is her present different from the past? Find hints/phrases from the poem which give you the idea that house was deserted after the death of the grandmother?
Answer:

• She had been given too much love in the past. But in the present, she is begging for love.
• The house withdrew into silence and snakes moved among the books.

My Grandmother’s House Kerala Syllabus 8th Activity 2.

Look at the phrase ‘blind eyes of windows’.
(i) Do you think that windows have eyes?
(ii) Aren’t ‘eyes’ a feature of living beings?
(iii) Is the poet attributing human qualities to ‘windows’? How?
Here the poet uses personification’. Personification is a figure of speech where a thing, an idea or an animal is given human attributes. E.g. The flowers danced in the breeze. Pick out another example of personification from the poem.
Answer:
Eg. Eye of the windows
Windows do not have eyes. Eyes, a feature of living beings is attributed to windows.
‘…. pick an armful of Darkness to bring it here to lie Behind my bedroom door like a brooding Dog…’

My Grandmother Questions And Answers Kerala Syllabus 8th Activity 3.

……… my blood turned cold like the moon’ is an example of simile. Pick out another simile from the poem.
Answer:
Simile: Behind my bedroom door like a brooding dog.

My Grandmother’s House Malayalam Translation Kerala Syllabus 8th Activity 4.

‘……….. blood turned cold’ is an instance of a tactile image. Find out other images from the poem.
Answer:
Snakes moved among books – Visual image
Peer through blind eyes – Visual image
Listen to the frozen air – Auditory image
Pick an armful of darkness – Visual
By now at stranger’s door – Visual

My Grandmother’s House Additional Questions and Answers

Read the lines from the poem ‘ My Grandmother’s House’ and answer the following questions.
I received love… That woman died,
The house withdrew into silence, snakes moved
Among books, I was then too young
To read, and my blood turned cold like the moon.
How often I think of going
There, to peer through bind eyes of windows or
Just listen to the frozen air
1. Who is the woman referred here?
2. Why did the house withdraw into silence?
3. The expression ‘blind eyes of windows’ is an example of (simile/ metaphor/ personification)
4. Why does the speaker want to go back to the house?
Answer:
1. Grandmother.
2. Because grandma died
3. Metaphor/ personification
4. To catch the memories of love.

Question 5.
Prepare a short profile of Kamala Surayya using the hints given below.
Born. : March 31, 1934
Famous as: Indian English poetess and a leading Malayalam author from Kerala.
Penname: Madhavikutty
Major works: The Sirens, Summer in Calcutta, My Story, Alphabet of Lust
Notable awards: Ezhuthachchan Puraskaram, Vayalar Award, Sahitya Akademi award
Died: May 31, 2009, age 75
Answer:
Kamala Surayya:
Kamala Surayya was born on March 31 in 1934. She was a leading English poetess and a leading Malayalam author from Kerala. She was known by her pen name Madhavikutty. The Sirens, Summer in Calcutta, My Story and Alphabet of Lust are her notable works. She was awarded the Ezhuthachchan Puraskaram, Vayalar Award, and Sahitya Akademi award. She passed away at the age of 75 on May 31, 2009.

Question 6.
Given below are some of the headlines found in newspapers. Read them carefully and answer the questions that follow.
A. India sweeps Series against England
B. Oil Price ‘inflammable’
C. Noted poet Mullanezhi passes away
D. Teacher’s package announced
E. Two found dead in road mishap
1. A headline that can be called an obituary is …………………..
2. The headline that can upset a vehicle owner is ………………
3. Which headline is related to educational news?
4. The headline that reports an accident is …………….
5. Which headline conies under the category of sports news?
Answer:
1. Noted poet Mullanezhi passes away
2. Oil Price Inflammable
3. Teacher’s package announced
4. Two found dead in road mishap
5. India sweeps Series against England

My Grandmother’s House Summary in English

The poetess recalls the house where she once used to live with her grandmother who was very fond of her and from whom she used to receive a lot of love. The grandmother had died, and the house had then ceased(stopped) to be inhabited by any¬body. The poetess was in those days a little girl and did not even know how to read the books which lay in the house. The death of her grandmother had made the little girl lose her capacity to feel. It had seemed to her that the blood in her veins was no longer warm but had turned cold, as cold as the moon.

The poetess now often thinks of going to that house in order to look at the things inside it through the windows; but the windows being closed she would not be able to see anything lying inside, and would be able only to experience a feeling of utter hopelessness, and then to gather some of the darkness from that place and bring it with her to her bedroom where she would merely lie down to meditate upon her memories of the past. Addressing her husband, Kamala Surayya says that he would perhaps not be able to believe that she had lived in such a house, had felt proud of herself, and had received the love of someone (namely her grandmother). She no longer receives any love from anybody. Now she seeks love like a beggar from strangers, and she would feel consoled even if she gets a small measure of love from somebody

My Grandmother’s House Glossary

You can Download Metals Questions and Answers, Summary, Activity, Notes, Kerala Syllabus 8th Standard Basic Science Solutions Chapter 7 help you to revise complete Syllabus and score more marks in your examinations.

Kerala State Syllabus 8th Standard Basic Science Solutions Chapter 7 Metals

Metals have some general charac-teristics. They are thermal conductors and electrical conductors. Metals can be beaten into thin sheets by hammering (malleability). Metals can be drawn into thin fine wires (ductility). Hardness is yet another property of metals. The surface newly formed when metals are cut, has a shining appearance (metallic lustre) Metals have the ability to produce sound when tapped with a hard material (sonority).

Metals have high melting point and density. Making use of these characteristics of metals they are used in various purposes. Metals are used to make electric wire because of its electrical conductivity. They are used to make utensils as the metals are thermal conductors. Metals have high density. So they are used to make farming tools. The sonority of metal is utilised to make bells in the places of worship.

There are some similarities in chemical properties of metals. Almost all the metals get tarnished when they are exposed to air for some days. This is because they are react with various components of atmospheric air.

Metals react with water. Metals like sodium, potassium etc reacts with cold water to liberate hydrogen.
Zinc, aluminium, iron, magnesium etc. react with dilute hydrochloric acid to form hydrogen along with salt of metal. There are some metals which does not react with acids.
Ex : Copper.

As the metals react with atmospheric air and water vapour causes corrosion. The iron reacts with air and water vapour. So it undergoes corrosion. Verdigris is formed on copper by reacting with the components of air. Iron and a number of other metals react with different components of air and form new products. This process is known as corrosion of metals. Painting on the metal, electroplating with non corrosive metals are some methods to prevent the corrosion

Metals Textbook Questions and Answers

Kerala Syllabus 8th Standard Chemistry Notes Question 1.
Some metals are listed below. Complete the table by identifying the different uses and the properties which are responsible for the same.

Answer:

Metal	Use	Property
Gold	To make ornaments To make coins	Ductility Malleability
Copper	To make utensils To make electric wire	Thermal conductivity Electrical conductivity
Aluminium	To make utensils To make aluminium foil	Thermal conductivity Malleability
Zinc	To make thin sheets In electric equipments	Malleability Electrical conductivity
Iron	To make farming tools To make utensils	Hardness Thermal conductivity

Hss Live Guru 8 Chemistry Kerala Syllabus Question 2.
Iron is a metal which corrodes fast.
a. What are the factors that favour the corrosion of iron?
b. In coastal regions, copper nails are preferred to iron nails. What could be the reason?
c. Can you suggest some measures to prevent the corrosion of iron?
Answer:
a. Air and water vapour in the atmo sphere
b. Iron rod corrodes quickly in salt water
c. Painting on the metal, electroplating with non corrosive metals

Hsslive Guru Chemistry 8 Kerala Syllabus Question 3.
Based on the physical properties of metals, indicate whether the following statements are true or false

1. Aluminium is a conductor of electricity.
2. The metal caesium melts at high temperatures.
3. Platinum is a metal with poor malleability.
4. Potassium is a hard metal.
5. Copper, metal is sonorous.
6. The density of gold is very low.
7. Copper is a good conductor of heat.
8. Sodium is a hard metal.
9. One of the reasons for the use of gold in making ornaments is its metallic lustre.
10. The ductility of tungsten is high.

Answer:

1. true
2. false
3. true
4. false
5. true
6. false
7. true
8. false
9. true
10. true

Hsslive Guru 8th Basic Science Kerala Syllabus Question 4.
Which among the metals is stored in kerosene?
(a) Sodium
(b) Iron
(c) Tungsten
(d) Chromium
Why is it stored in kerosene?
Answer:
a. Sodium. Becuase they vigorously react with air.

Kerala Syllabus 8th Standard Physics Notes Question 5.
The names of some metals are given below.
Tungsten, Gold, Sodium, Copper, Iron, Magnesium
Answer the following questions by selecting the appropriate ones from the list.

• Which metal with high malleability is used for making ornaments?
• Which of these metals reacts with cold water?
• Which of these is a hard metal but corrodes easily?

Answer:

• Gold
• Sodium
• Iron

Hsslive Guru Chemistry Class 8 Kerala Syllabus Question 6.
Give reasons for the following statements.

• Tamarind is not stored in aluminium vessels.
• It is a common practice to apply oil on iron articles and tools.
• Stainless steel knives, instead of iron knives, are preferred for cutting citrus fruits.

Answer:
a. Tamarind is acidic. So aluminium corrodes by reacting with acid
b.To reduce the contact with air
c. Gtrus fruit is acidic. It reacts with iron.

Hsslive Class 8 Chemistry Kerala Syllabus Question 7.
Connect a torch bulb to the battery with the different metal wires. Find out which wire gives the highest brightness to the bulb? Arrange the wires in the decreasing order of their electrical conductivity.
Answer:
Iron-copper-aluminium-nichrome

Hsslive.Guru Class 8 Kerala Syllabus Question 8.
Collect the following materials: an iron nail, an aluminium wire, a pencil lead, a copper Beat them hard using a hammer. Which of thenvCan he flattened? What is your conclusion from this experiment?
Answer:
Iron nail, aluminium wire. The metals have malleability.

Class 8 Physics Notes Kerala Syllabus Question 9.
You have understood the properties of metals. Find out the metals mentioned in the following cases.
a. Which metal is used in the storage batteries of vehicles?
b. Most of the metals are solids. Which metal exists as a liquid even at low temperatures?
c. Iron articles are coated with other metals to protect them from corrosion. Which are the two metals usually used for this purpose?
d. Metals have high density. Which is the densest metal?
Answer:
a. zinc
b. mercury
c. zinc, magnesium
d. gold

Metals Additional Questions and Answers

Hsslive 8 Chemistry Kerala Syllabus Question 1.
Tabulate the general properties of metals
Answer:
Hardness, High density, Ductility, Malleability, Sonority, Thermal conductivity, Electrical conductivity.

Hss Live Guru 8 Kerala Syllabus  Question 2.
List some of the general properties of metals.
Answer:
Generally metals, are good conductors of electricity, are good conductors of heat, are malleable (can be hammered into thin sheets), are ductile (can be pulled into wires), are solids (except mercury), are hard and strong, have metallic lustre, have high densities, have high melting points, have high boiling points

Hss Live Guru Class 8 Kerala Syllabus Question 3.
What are the situation make use of the following properties of metals Hardness, malleability, thermal conductivity, electrical conductivity, ductility
Answer:
To make farming tools
• To make aluminium foil,
• To make utensils
• To make electrical equipments
• To make ornaments

Hss Live Guru 8th Chemistry Kerala Syllabus Question 4.
Write the following metals in the ascending order of electrical conductivity. Silver, copper, aluminium
Answer:
Aluminium, copper, silver

Hsslive Guru 8th Class Chemistry Kerala Syllabus Question 5.
Even though the electric conductivity is less the wires on electric posts are made up of aluminium. Why?
Answer:
Due to less weight and cost.

Question 6.
Which metal is seen in liquid state?
Answer:
Mercury

Question 7.
Fill the table

Use	Property
To make utensils	……………………….
To make aluminium foil	……………………….
To making farming tools	……………………….
To make electric wire	……………………….
To make bells	……………………….

Answer:

Use	Property
To make utensils	thermal conductivity
To make aluminium foil	malleability
To making farming tools	hardness
To make electric wire	electrical conductivity
To make bells	sonority

Question 8.
Butter milk is not kept in aluminium vessels. Why?
Answer:
Butter milk is acid. So it reacts with aluminium

Question 9.
What are the two things which are caused to form verdigris on copper?
Answer:
Air and water vapour

Question 10.
Select the metals which do not react with air.
Copper, iron, gold, magnesium, platinum, sodium, silver
Answer:
Gold, silver, platinum

Question 11.
Write the following rentals in the ascending order of the reactivity with acids. Copper, sodium, iron, aluminium
Answer:
Sodium, iron, aluminium, copper

Question 12.
Why should we paint the iron bars of window?
Answer: To protect them from rusting

Question 13.
What are the components effecting rusting of iron?
Answer:
Air, moisture present in atmosphere

Question 14.
Why sodium and potassium are kept in kerosene?
Answer:
Because they vigorously react with air.

Question 15.
Aluminium vessels get tarnished after few days they purchased. Why?
Answer:
aluminium undergo chemical reaction with air and a covering is formed.

Question 16.
The window bars near sea shore undergo rusting quickly. Why?
Answer:
Iron react with saltwater quickly and undergo corrosion.

Question 17.
Which property of metals is used to make bells.
Answer:
Sonority

Question 18.
What is the property of metal caused for shining appearance?
Answer:
Metallic lustre.

Question 19.
Which is the metal used for making filament of bulb? Which property is made use of it.
Answer:
Tungsten; ductility.

Question 20.
Is there any advantage, if iron nails are kept inside kerosene. Why?
Answer:
Yes, it prevent rusting. Iron nails, when kept inside kerosene, are protected from rusting. They are not in contact with atmospheric air or moisture.

Question 21.
A bottle filled with quicklime is closed with a lid made of iron. After some days, when the lid is opened, which part of the lid is more rusted? What is the reason for that?
Answer:
The outer part of the lid is more rusted. The outer part is in contact with air and moisture; but due to the presence of quicklime, there is no water content inside.

Question 22.
Find the odd one out. Write the reason.
a. Iron, aluminium, sodium, copper
b. Silver, gold, sulphur, lead
Answer:
a. Sodium. Sodium is a soft metal while others are hard metals b. Sulphur. Sulphur is a non-metal others are metals.

Question 23.
Which are the metals found in free state! Why?
Answer:
Metals like gold, platinum, silver, copper etc. are found in free state, . because these metals do not react with air.

Question 24.
To prepare thin sheets, metals are beaten and made into thin sheets.
a. What is the name of this property of metals by which they can be beaten into thin sheets?
b. Which metals can be beaten and made into the thinnest sheet?
Answer:
a. Malleability
b. Gold

Question 25.
Among the statements given below which are true about metals.
a. Metals bum
b. Metals can be beaten into thin sheets.
c. Metals are dull in appearance.
d. Metals are good conductor of heat.
e. Metals conduct electricity.
f. Metals break into small pieces when struck with a hammer.
Answer:
b, d, and e

Question 26.
Does any immediate change occur when a bright nail is exposed to air? What happens to it after a few days?
Answer:
Tmmediate change does not occur. After a few days it reacts slowly with air and gets a coating of oxide.

Question 27.
Why are aluminium rods not used to reinforce concrete?
Answer:
Pure aluminium is thin, not sufficiently hard and strong. So aluminium rods are not used to reinforce concrete.

Question 28.
Iron made objects will undergo quick rusting. Give reason? What are the methods used to prevent the speed of the process?
Answer:
Tron became destroyed when it can react with atmospheric oxygen and moisture form hydrated iron oxide (rust)

• Painting, apply grease or oil
• Covered the iron by using highly active metals like zinc
• Apply tin on iron. ,
• Protect iron made object by applying nickel and chromium on it.

You can Download From The Merchant of Venice Questions and Answers, Summary, Activity, Notes, Kerala Syllabus 8th Standard English Solutions Unit 5 Chapter 2  helps you to revise complete Syllabus and score more marks in your examinations.

Kerala State Syllabus 8th Standard Hindi Solutions Unit 4 Chapter 2 The Merchant of Venice (William Shakespeare)

The Merchant of Venice Textbook Questions And Answers

The Merchant Of Venice Questions And Answers Kerala Syllabus Question 1.
Why did Bassanio approach Antonio?

Answer:
Bassanio approached Antonio to borrow money as he wanted to dress himself up as a suitor to Portia, the rich heiress.

The Merchant Of Venice Class 8 Questions And Answers Kerala Syllabus Question 2.
Who was Shylock and how did he become rich?

Answer:
Shylock was a money lender. He became rich by lending money at a very high interest to the merchants.

Merchant Of Venice Questions And Answers Kerala Syllabus  Question 3.
Why did Shylock hate Antonio?

Merchant of Venice Questions and Answer:
Because Antonio used to lend money to the needy without taking any interest.

The Merchant Of Venice Question Answers Class 8 Kerala Syllabus Question 4.
What was Antonio’s attitude towards Shylock?

Answer:
Antonio disliked Shylock.

The Merchant Of Venice Class 8 Kerala Syllabus Question 5.
What were the conditions in the bond signed between Antonio and Shylock?

Answer:
If he didn’t repay the money in time, he would forfeit a pound of flesh, to be cut off from any part of his body.

Merchant Of Venice Question Answers Kerala Syllabus Question 6.
‘No’, cried Bassanio, ‘you shall run no such risk for me’. What is the risk referred to here?


Answer:
The risk is that Antonio may lose his life if they are unable to pay the debt.

Merchant Of Venice Summary For Class 8 Kerala Syllabus Question 7.
What were the caskets made of?

Answer:
The first casket was made of gold, the second one silver and third one was made of lead.

The Merchant Of Venice Questions And Answers Class 8 Kerala Syllabus Question 8.
Why did Portia arrive in Venice disguised as a lawyer?

Answer:
To help Antonio

Merchant Of Venice Class 8 Pdf Kerala Syllabus Question 9.
Why did Shylock insist on having the pound of flesh?

Answer:
He wanted to take revenge on Antonio whom he hated.

The Merchant Of Venice Question And Answer Kerala Syllabus Question 10.
Why did Shylock refuse the money offered by Bassanio?

Answer:
Because he wanted to see Antonio dead.

The Merchant Of Venice Question Answer Kerala Syllabus Question 11.
‘Hearing this, Shylock was totally confused’. Why was Shy-lock confused?

Answer:
It was utterly impossible for Shylock to cut off the pound of flesh without shedding Anotonio’s blood.

The Merchant Of Venice Question Answers Kerala Syllabus Question 12.
Why was Shylock ready to take the money?

Answer:
Because he was cornered. He had defeated himself in his cruel intent.

The Merchant Of Venice Class 8 Summary Kerala Syllabus Question 13.
What did the young lawyer ask as reward?

Answer:
The young lawyer wanted Bassa nio’s ring that was presented to him by his wife, Portia.

Merchant Of Venice Questions And Answers Class 8 Kerala Syllabus Question 14.
How does the play become a comical adventure at the end?

Answer:
The play becomes a comical adventure when Bassanio realizes that the young lawyer was his wife Portia in disguise

The Merchant of Venice Textbook Activities And Answers

Let’s revisit

The Merchant Of Venice Question And Answers Kerala Syllabus Activity 1.

The following events are in a jumbled order. Put them in the correct order as a paragraph.

Merchant Of Venice Question And Answer Kerala Syllabus Question 1.
A. 1. Shylock lends Antonio three thousand ducats.
2. Portia married Bassanio.
3. Antonio failed to pay the debt.
4. Shylock hated Antonio because he used to lend money without interest.
5. Shylock wanted Antonio’s flesh.
6. Portia rescued Antonio from the punishment.

B. 1. Portia arrived disguised as a young lawyer.
2. Shylock was not ready to be merciful.
3. The young lawyer saved the life of Antonio.
4. The day of the trial arrived.
5. Antonio was prepared to die.
6. The Duke pleaded with him to be kind.
Answer:
A. 1. Shylock hated Antonio because he used to lend money without interest.
2. Shylock lends Antonio three thousand ducats.
3. Portia married Bassanio.
4. Antonio failed to pay the debt.
5. Shylock wanted Antonio’s flesh.
6. Portia rescued Antonio from the punishment

B. 1. The day of the trial arrived.
2. The Duke pleaded with him to be kind.
3. Shylock was not ready to be merciful.
4. Antonio was prepared to die.
5. Portia arrived disguised as a young lawyer.
6. The young lawyer saved the life of Antonio.

The Merchant of Venice Additional Questions and Answer

The Three Caskets Questions And Answers Class 8 Kerala Syllabus Questions 1 to 5.
Read the excerpt from the story ‘ The Merchant of Venice’ and answer the questions that follow.

Bassanio loved a girl named Portia, a very wealthy lady living in Belmont. Her father died some time ago and she was the only heiress to a large estate. Portia too loved Bassanio. Now he thought of improving his fortune by marrying her. One day Bassanio came to Antonio and told him about his love for Portia and that he must go very soon to Belmont as a suitor to Portia. But he did not have any money even to dress himself suitably as the lover of so rich an heiress. So he asked Antonio to help him. Bassanio wanted his friend to lend him three thousand ducats. But it so happened that Antonio had spent all his money on his ships and so had no money with him.

But he expected some of his ships to come home soon laden with merchandise. Hence, he decided to borrow the amount from Shylock who was a money lender. Shylock had become very rich by lending money at a very high interest to merchants. He was a hard-hearted man and was very severe with his customers. So, he was much disliked by all good men. Antonio also disliked Shylock for being so ambitious and greedy for money. He used to lend money to the needy people without taking any interest. Therefore there was great enmity between the greedy Shylock and Antonio.
1. What was the name of Bassanio’s lover?
2. Why did all the good men dislike Shylock?
3. What did Bassanio ask Antonio to lend him?
4. Why couldn’t Antonio help Bassanio?
5. Pick out a word from the passage that means ‘rich’.
Answer:
1. Portia
2. Shylock was a hard-hearted man and was very’ severe with his customers. So he was disliked by all good men.
3. Three thousand ducats
4. Antonio had spent all his money on ships and so had money with him.
5. Wealthy

Question 6.
The English Club of your school has decided to stage the play ‘ The Merchant of Venice’ by William Shakespeare. Prepare a notice to inform the staff and the students, giving the relevant details.
Answer:

THE MERCHANT OF VENICE
A play presented by English club of XYZ School

Dear Friends,
The English Club of XYZ School has decided to stage the one-act play based on the story ‘The Merchant of Venice’ by William Shakespeare as a part of the Annual day celebrations of the school. The members of the English Club have prepared the script and directed the play. Sri Kavalam Narayana Panicker, the renowned poet and theatre personality has consented to inaugurate the staging of the play.

All are Welcome

Question 7.
Complete the passage using the words given in the bracket.
(with, across, is, allows, an)
It is still drizzling. The boy ….(a) seen running after a woman who has ……. (b)……… with her. He reaches her, holds the balloon under her umbrella and walks with her. Then the boy walks up to two nuns ……….. (c) ……… umbrellas. One of them ………. (d) ……… him to hold the balloon under the umbrella. After that the boy is seen walking with a man ………… (e) ……….. a bridge holding the balloon under the man’s umbrella.
Answer:
a. is
b. an
c. with
d. allowed
e. across

The Merchant of Venice Summary in English

The young Venetian Bassanio needs a loan of three thousand ducats to marry his lover Portia a wealthy lady in Belmont. He approaches his friend Antonio, a merchant but he is in short of money because he spent all his money on his ships and so he had no money with him. So Antonio goes to a Jewish moneylender, Shylock, who hates him because Antonio used to lend money to the needy without taking any interest. Shylock nevertheless agrees to make the short-term loan, but, he makes a condition – the loan must be repaid in three months or Shylock will cut a pound of flesh from Antonio. Antonio agrees, confident that his ships will return in time. Because of the terms of Portia’s father’s will, all suitors must choose from among three caskets, one of which contains a portrait of her. Bassanio chooses the lead casket, which contains her picture, and Portia happily agrees to marry him immediately. Meanwhile, two of Antonio’s ships have been wrecked and Shylock pressurized him for repayment.

Word comes to Bassanio about Antonio’s predicament, and he hurries back to Venice, leaving Portia behind. Portia follows him, accompanied by her maid, Nerissa. They are disguised as a male lawyer and his clerk. When Bassanio arrives the date for the repayment to Shylock has passed and Shylock is demanding his pound of flesh. Even when Bassanio offers much more than the amount in repayment, Shylock does not agree. Portia arrives in her disguise to defend Antonio. Given the authority of judgment by the Duke, Portia decides that Shylock can have the pound of flesh as long as he doesn’t shed a drop of blood. At last half of Shylock’s wealth was given to Antonio and other half went to the state. Antonio was released and Shylock was humiliated. Portia tells Bassanio that she came disguised as the young counselor. Antonio’s ships finally arrive.

The Merchant of Venice Summary in Malayalam

The Merchant of Venice Glossary

You can Download Chemical Change Questions and Answers, Summary, Activity, Notes, Kerala Syllabus 8th Standard Basic Science Solutions Chapter 6 help you to revise complete Syllabus and score more marks in your examinations.

Kerala State Syllabus 8th Standard Basic Science Solutions Chapter 6 Chemical Change

Chemical Changes Questions and Answers

All the changes in nature is divided into physical changes and chemical changes. During a physical change, only a change in the arrangement of molecules occurs. Hence it can be easily brought back to its original state. In the case of chemical changes, new molecules are formed.

The alkali formed by the reaction of sodium with water is sodium hydroxide. Because of its basic nature it becomes pink colour when phenolphthalein is added to it.

In the reaction of magnesium burns in air heat and light are produced.

Chemical Changes Class 8 Kerala Syllabus Thermo chemical reactions

The reaction of magnesium with dil. hydrochloric acid, hydrogen is produced and heat is evolved. So we feel hot when we touch the test tube.
Mg + 2HCl → MgCl₂ + H₂ + heat

Take a few crystals of potassium permanganate in a dry test tube. Heat the test tube. Bring a glowing incense stick to the mouth of the test tube. When potassium permanganate is heated, it decomposes to form potassium mangnate, manganese dioxide. and oxygen. In this reaction, potassium permanganate decomposes with absorption of heat and oxygen is evolved.

Add hydrochloric acid to a concentrated solution of sodium hydroxide taken in a test tube. Heat is evolved. Chemical reactions which liberate heat are called exothermic reactions and those which absorb heat are called endothermic reactions.

Chemical Changes Class 8 Notes Kerala Syllabus Photochemical reactions

Photosynthesis is a chemical reaction that is responsible for sustaining life on earth. In this reaction, plants produce glucose by absorbing light. Note the chemical equation of this reaction.
6 H₂ O + 6 CO₂ + Light → C₆ H₁₂ O₆ + 6 O₂

The glucose thus formed is stored by plants in the form of starch.

Take some silver bromide in watch glasses. That will change to black because silver is precipitated.

Chemical reactions which liberate or absorb light energy are known as photochemical reactions.

Chemical Changes Class 8 Kerala Syllabus Electrochemical reactions

The change in colour of copper sulphate solution and the deposition of copper at the electrode proves that a chemical change has occurred.

In this reaction, copper sulphate decomposed with the absorption of electrical energy. The process in which a substance undergoes decomposition by the absorption of electrical energy is known as electrolysis.

Here, electricity is produced as a result of a chemical reaction between the acid and the metals kept immersed in it. Such arrangements which produce electricity as a. result of chemical reaction are known as electrochemical cells.
We can make cells using a variety of fruits and different metals like zinc. Chemical reactions in which electrical energy is consumed or produced are known as electrochemical reactions.

Chemical Changes Standard 8 Kerala Syllabus Electroplating

You are familiar with the gold plated ornaments that are available in the market. Electricity is used to obtain a thin coating of a particular metal on other metallic objects. This process is called electroplating.

Now, you might have understood that forms of energy like heat, light and electricity are exchanged during chemical reactions. There are chemical reactions which involve the absorption or liberation of energy. Those which absorb energy are known as endoergic reactions and those which liberate energy are known as exoergic reactions.

Energy transfer occurs during any chemical reaction. A chemical reaction will be known based on the major energy form which gets absorbed or liberated.

Kerala Syllabus 8th Standard Chemistry Notes Different types of cells

The cells are the electric source commonly used. Following is the table of cells and their uses

Cells	Equipment used
Dry cell	• Radio
	• Camera
	• Clocks
	• Toys
Mercury cell	• Watches
	• Calculators
	• Electric instruments
Nickel-cadmium cell	• Rechargeable torches
	• Cameras
Lithium-iron cell	• Mobile phones
	• Laptops

Hsslive Guru Chemistry 8 Kerala Syllabus Environment friendly changes

Many natural and manmade chemical changes that occur around us are not nature – friendly. Nature tries its best to adapt these changes But after a limit it destroy the harmony of nature. The chemicals coming out from the factories will make the problem serious. Hence, accumulation of those materials, which cannot be biodegraded may become a threat even to the existence of life itself. For the sake of posterity, it is the duty of each one of us to protect the earth’from getting polluted.

Chemical Changes Textbook Questions and Answers

Electrolytic water Equipment Factory Question 1.
Assess the chemical reactions given below and answer the questions.
1. Calcium carbonate + heat → Calcium oxide + Carbon dioxide
2. Calcium oxide + water → Calcium hydroxide + heat
a. Mention the reactants and products in each case.
b. Which among these is endothermic? Which one is exothermic?
Answer:
a.Reactants:
1. Calcium carbonate
2. Calcium oxide, water
Products
1. Calcium oxide, carbon dioxide
2. Calcium hydroxide
b.First reaction is endothermic and second is exothermic reaction.

Hsslive Guru 8th Class Chemistry Kerala Syllabus Question 2.
Some chemical reactions are given below. Identify the energy change involved and write down what type of chemical reaction takes place here.
a. Burning of a candle
b. Glowing of a fire fly
c. Plating a copper ring with gold
d. Reaction between potassium hydroxide and sulphuric acid
e. Burning of fuels
Answer:
a. Thermochemical reactions
b. Photochemical reaction
c. Electrochemical reaction
d. Thermochemical reactions
e. Thermochemical reactions

Kerala Syllabus 8th Standard Chemistry Notes Malayalam Medium Question 3.
A student tries to plate an iron nail with copper. Draw its arrangement by selecting the required materials from the list given below.
Silver nitrate, iron nail, copper sulphate, silver rod, copper rod, silver plate, iron sulphate, battery, wire, water, beaker.
Answer:

8th Standard Chemistry Textbook Answers Kerala Syllabus Question 4.
List out the instruments that use electrochemical cells. What are the merits and demerits of using such cells?
Answer:

Cells	Equipment used
Dry cell	• Radio
	• Camera
	• Clocks
	• Toys
Mercury cell	• Watches
	• Calculators
	• Electric instruments
Nickel-cadmium cell	• Rechargeable torches
	• Cameras
Lithium-iron cell	• Mobile phones
	• Laptops

Std 8 Chemistry Notes Kerala Syllabus  Question 5.
Classify the following into physical changes and chemical changes.
1. Melting of ice.
2. Heating magnesium in water.
3. Silver bromide kept exposed to sunlight.
4. Change happening to soda water on opening its bottle.
Answer:
1. physical change
2. chemical change
3. chemical change
4. physical change

8 Standard Chemistry Notes Kerala Syllabus Question 6.
Give an example each for exothermic and endothermic reactions.
Answer:
Exothermic reaction:
Magnesium + hydrochloric acid → magnesium chloride + hydrogen + heat
Endothermic reaction:
Potassium permanganate + heat → potassium manganate + manganese dioxide + oxygen

Hss Live Guru 8th Chemistry Kerala Syllabus Question 7.
Making a volcano
Heap up some ammonium dichromate powder on a tile. Deposit on it the chemical present on a match stick, and ignite. Write down the changes happening there.
Change in colour: …………………………..
Change in amount: …………………………..
Exchange of energy: …………………………..
Answer:
Change in colour – orange-red Change in quantity – decreases Energy exchange – exothermic

Hsslive Guru Chemistry Class 8 Kerala Syllabus Question 8.
Kindling fire by pouring oil. Heap up some potassium permanganate on a tile. Keep a piece of dry cotton wick on top of it. Pour one or two drops of glycerine on the wick. Observe the changes.
Answer:
potassium permanganate heap burns

Basic Science Class 8 Chapter 6 Kerala Syllabus Question 9.
Take a magnesium ribbon and clean it by scrubbing. Then burn it in air. Collect the product formed and dissolve it in water. Dip litmus papers and pH paper in this solution and observe. Find out the reason for the results of the observations.
Answer:
Red litmus changes to blue. This is because of the magnesium hydroxide produced when magnesium oxide dissolved in water is alkaline.

8th Standard Chemistry Notes Kerala Syllabus Question 10.
Take sodium chloride solution in a beaker. Add to it a few drops of phenolphthalein. With the help of two carbon rods, let electricity pass through the solution. Record your observations. What is your inference?
Answer:
Sodium chloride is decomposed into sodium and chlorine

Question 11.
Take some silver nitrate solution in a test tube and add some sodium chloride solution to it. What is the colour of the precipitate formed? Filter the precipitate using a filter paper, place it on a watch glass and keep it exposed to sunlight. What do you observe?
Try to write down the equation of your observation with the help of your teacher.
Identify the change of energy involved in the second chemical reaction and write down what type of chemical reaction it is.
Answer:
White precipitate. It will become black when it is opened in sunlight.
Energy change: photo chemical reaction

Chemical Changes Additional Questions and Answers

Question 1.
i. sodium + water → sodium hydroxide + hydrogen
ii. Magnesium + oxygen → magnesium oxide
Write the reactants and products of these reactions.
Answer:
i. Reactants: sodium, water
Products: sodium hydroxide, hydrogen
ii. Reactants: magnesium, oxygen
products: Magnesium oxide

Question 2.
What is the observation when two drops of phenolphthalein is added to the solution obtained after the reaction of sodium with water? Justify your answer.
Answer:
The solution becomes pink in colour. The product of the reaction is sodium hydroxide which is alkaline.

Question 3.
Tabulate the following changes into physical and chemical changes

• Water changes to water vapour
• burning wood
• rusting the iron
• explosion of crackers
• cutting the wood
• Magnesium burns in air
• Ice is melting

Answer:
Water changes to water vapour – Physical change
Burning wood – Chemical change
Rusting the iron – Chemical change
Explosion of crackers – Chemical change
Cutting the wood – Physical change
Magnesium burns in air – Chemical change
Ice is melting – Physical change

Basic Science for Class 6 Chapter 6 Question 4.
Tabulate the important energy change in the following reactions.

1. Magnesium burns in air
2. Heating potassium permanganate
3. Photosynthesis
4. Electroplating
5. Reaction between Sodium hydroxide and Hydrochloric acid
6. Glittering the fire fly
7. Reaction in electrochemical cells

Answer:

1. Liberates heat energy
2. Absorbs heat energy
3. Absorbs light energy
4. Absorbs electric energy
5. Liberates heat energy
6. Liberates light energy
7. Liberates electric energy

Iron Sulphate Question 5.
Examine the following substances and draw the figure which shows the arrangement of coating silver on an iron ring Gold wire, silver rod, iron ring, copper sulphate, solution of silver cyanide and gold cyanide battery, beaker
Answer:

Question 6.
Some medicines and chemicals are kept in dark bottles, why?
Answer:
To prevent the chemical change due to the absorption of light

Question 7.
What is elecroplating? How are the electrode and the electrolyte selected when a metallic object is to be plated with another special metal?
Answer:
To obtain a thin coating of a particular metal on another metallic object using electricity is known as electroplating.

The metal to be plated is taken as the positive electrode. The electrolyte is a solution of salt containing the metal to be plated. The negative electrode is the metallic object to be plated.

Question 8.
What is your observation when a glowing in inscent stick is brought to the mouth of test tube containing potassium permanganate which is heated? Give reason.
Answer:
The stick flares up. When potassium permanganate is heated, it decomposes to form potassium manganate, manganese dioxide and oxygen.

Question 9.
Give an example each for the reaction of liberation of heat and absorption of heat from daily life.
Answer:
Exothermic reaction: Burning of wood
Endothermic reaction: Marble is heated to quick lime

Question 10.
How electrical energy is produced by batteries?
Answer:
Tn a battery, electrical energy is produced by the chemical reaction between zinc and sulphuric acid or by zinc and carbon. Electrical energy is produced by chemical reactions. Here chemical energy is converted to electrical energy.

Question 11.
Photosynthesis is the reaction that responsible to sustain life on the earth. Write the equation of the reaction. What is the energy change in it?
Answer:
6H₂O + CO₂ → C₆H₁₂ O₆+ 6O₂
Light energy is absorbed in it.

Question 12.
Complete the figure given below

Answer:

Question 13.
Acid is added to water for its electrolysis. Why?
Answer:
Pure water is not an electric conductor. But if some acid, alkali or salt is added, lot of ions are formed in it and water will become an electric conductor.

Question 14.
When electricity is passed through copper sulphate solution using carbon electrodes kept in the solution, it decomposes.
A. By what name this process in known?
B. In which electrode is copper deposited dining the reaction?
C. Is there a colour change for the solution?
Answer:
a. Electrolysis
b. Negative electrode
c. The colour of the solution decreases.

You can Download Magnetism Questions and Answers, Summary, Activity, Notes, Kerala Syllabus 8th Standard Basic Science Solutions Chapter 11 help you to revise complete Syllabus and score more marks in your examinations.

Kerala State Syllabus 8th Standard Basic Science Solutions Chapter 11 Magnetism

Nowadays artificial magnets are used commonly. They are made by the alloy like alnico.

A magnet possesses directional property that a freely moving magnet always aligns itself in the north-south direction. If a magnet is arranged in such a way that it can move freely it will align itself in the north-south direction of the earth. It is because a magnet possesses directional property that a freely moving magnet always aligns itself in the north-south direction.

As far as magnets are concerned, like poles repel each other and unlike poles attract each other.

A compass is an instrument which is utilised the directional property of a magnet. Every magnet has two poles even if they are very small.

Magnetism Class 8 Notes Chapter 11 Kerala Syllabus Earth as a magnet

The earth acts like a large magnet. This was first discovered by the scientist William Gilbert. He found out that just as the earth has north and south geographically, it has the north pole and the south pole when considered as a magnet. The south pole of the earth’s magnet is near the geographic north pole and the north pole of the earth’s magnet is near the geographic south pole.

Magnetism Class 8 Notes Kerala Syllabus Chapter 11 Magnetic field

Magnetic lines of force are experienced in all dimensions around a magnet. The magnetic lines of force is experienced according to the strength of the magnet. Magnetic force is experienced in all dimensions around a magnet. This region around a magnet where the influence is felt is the magnetic field.

The flux density is the number of flux lines passing through unit area.

Kerala Syllabus 8th Standard Physics Notes Chapter 11 peculiarities of magnetic lines of force.

1. Magnetic lines of force do not intersect one another.
2. Magnetic lines of force bend sideways, when like poles of magnets come near each other.
3. When unlike poles of magnets come close to each other, the path of the magnetic lines of force is from the north pole of one magnet to the south pole of the other magnet.

The substances which are attracted by magnet is called magnetic substances.

Questions On Magnetism For Class 8 Kerala Syllabus Chapter 11 Magnetic Induction

Bring a pin in contact with the pole of a bar magnet. Is it not attracted? What if you bring another pin to the free end of the pin? It will also be attracted. If we bring another pin the second pin will attract the third. But when the first pin is removed from the magnet all pins will fall down. That is the pin acquired the magnetic force from the magnet.

The phenomenon of a magnetic substance acquiring magnetism due to the presence of a magnet is Magnetic Induction. The magnetic force acquired by the magnetic substance is the Induced Magnetism.

Whether under contact or without contact, the polarity of the magnet produced by induction will be like polarity at the further end and unlike polarity at the nearer end.

The ability of magnetic substances to get magnetised under the influence of a magnetic field is Susceptibility. Retentivity is the ability to retain the magnetism thus acquired. Soft iron has high susceptibility. But the ability to retain magnetism acquired (retentivity) is very low.

Permeability is the ability of substances to pass magnetic lines of force through them.

The ability of soft iron to permit magnetic lines of force pass through it is greater than that of air. That is, magnetic lines of force pass more easily through soft iron than through air.

Std 8 Physics Magnetism Notes Kerala Syllabus Chapter 11 Electromagnet

Electromagnets can be made by passing electric current through insulated copper wire wound on a soft iron piece. The strength of electromagnets made in this way depends on

• the number of turns of coiled conductor
• the strength of current
• the area of cross section of the soft iron placed inside the coil

All electromagnets are temporary magnets. If the current ceases to flow, the magnetism of the soft iron core is lost.

Magnetism Textbook Questions and Answers

Magnetism Chapter Class 8 Kerala Syllabus Chapter 11 Question 1.
In the figure, AB is a bar magnet. CD is a soft iron rod placed near the end B. Write down which poles develop at the ends C and

Answer:
C-north ,D-South

Class 8 Physics Notes Kerala Syllabus Chapter 11 Question 2.
Figures A and B show two iron nails each hanging from a bar magnet and a U shaped magnet.

a. Identify the correct picture in A and B.
b. Justify your answers.
Answer:
a. A – Fig III B – Fig II
b.In A two nails are hang from bar magnet. So the distant ends will be induced the same pole. So repulsion. But in U magnet at the distant opposite poles will be induced. So attraction.

Hsslive Guru 8th Class Physics Kerala Syllabus Chapter 11 Question 3.
You are given a soft iron piece, a steel piece of the same size, insulated copper wire and a battery.
a. Explain how a strong permanent magnet can be made.
b. Suggest a method to make a temporary magnet.
Answer:
a. Take a piece of steel and bind a insulated copper wire. Connect the ends of the wire to a cell
b. Wind a few turns of insulated copper wire on an iron nail. Connect the ends of the wire to a cell

Basic Science Class 8 Chapter 11 Kerala Syllabus  Question 4.
Can you build a compass and make it work by arranging a magnetic needle in such a way that it rotates freely inside an iron case? What is the reason?
Answer:
No. As the iron is a magnetic substance compass will not rotate freely.

Hss Live Guru 8th Physics Kerala Syllabus Chapter 11 Question 5.
In an exhibition, a plastic car with an iron piece fixed inside it is made to run on a wooden table by sliding a strong magnet below it. The experiment failed when a steel table was used instead. Explain the reason.
Answer:
Steel table has high permeability. It permit magnetic flux to pass through it. Therefore we cannot slide the car using magnet.

Magnetism Additional Questions and Answers

Class 8 Science Notes Kerala Syllabus Chapter 11 Question 1.
Name the following magnet.

Answer:
a. Bar magnet,
b. compass,
c. U magnet,
d. Ring magnet,
e. Magnetic plate

8th Class Biology Notes Pdf Malayalam Medium Chapter 11 Question 2.
Which instrument is used to identify the direction in ship journey in ancient time?
Answer:
Compass

8th Class Biology Notes Pdf Kerala Syllabus Chapter 11 Question 3.
A bar magnet is hanged by a thread. Where does the north pole of the magnet point?

Answer:
The north pole of the compass points towards north of the earth that is south pole of earth’s magnet be¬cause earth is a magnet.

Kerala Syllabus 8th Standard Physics Notes Pdf Chapter 11 Question 4.
Write the magnetic substances from the following.
Wooden block, iron nail, paper, nickel, gold, cobalt, aluminium
Answer:
Iron nail, nickel, cobalt

Kerala Syllabus 8th Standard Chemistry Notes Chapter 11 Question 5.
Write the right statement
Greater susceptibility (Soft iron/Steel)
Greater retentivity? (Soft iron/ Steel)
Answer:
a. Soft iron b. Steel

Magnetism Chapter for Class 6 Question 6.
Write three method to increase the strength of an electromagnet.
Answer:

• the number of turns of coiled con ductor
• the strength of current
• the area of cross section of the soft iron placed inside the coil.

Magnetism Textbook Question 7.
You are given a bar magnet. The poles are not marked on it. Suggest a method to identify the poles of the magnet.
Answer:
The magnet is suspended using a thread so that it can oscillate freely in a horizontal plane. When it comes to rest the end pointing south can be marked as south pole.

Magnetism Solutions Question 8.
A magnet is dipped in iron filing, the iron fillings are more attracted towards the poles of the magnet than towards other places. Why?
Answer:
The intensity at the poles is greater than that at other places.

Question 9.
North of geomagnet inclined against 110 with geoscientific north pole? Examine the statement.
Answer:
The statement is incorrect. North of geomagnet inclined against 110 with geoscienfic south pole. Magnet suspended on geomagnet alinged south – north direction is due to the attraction of unlike poles. North pole (N) of magnet attracted towards the south pole of geomagnet.

Question 10.
What are the difference in the magnetic properties of iron and steel?
Answer:
Tron becomes a more intense magnet on magnetic induction. But that magnetic power is temporary. When the permanent magnet is removed it losses its magnetic power. In the presence of a magnet, steel doesn’t acquire the magnetic power like that of a soft iron. But steel retains most of its magnetic power after removing the permanent magnet.

Question 11.
Write your inferences.
a. All magnets have same shape.
b. All magnets show N, S direction when suspended freely.
c. All magnets are man made.
d. All magnets show N, S direction when suspended freely.
Answer:
a. No, There are different types of magnets.
b. Yes, Because the north pole of magnet turns to geographical south of earth and south pole turns to geographical north of earth.
c. No, There are natural and man made magnets.
d. Yes. Earth acts like a large magnet. Hence the poles of the suspended magnet is opposite to the poles of the earth’s magnet.

Question 12.
When an iron nail is wounded with copper wire and connected to a battery, it doesn’t become a magnet, select the reasons from the following.
a. Battery has not enough charge.
b. The insulation at the ends of the wire is not removed.
c. The nail is wounded with non insulated copper wire.
d. The polarity of the battery is changing.
Answer:
a,b,c

Question 13.
An Iron nail is suspended at the
north pole of a bar magnet. Bring the north pole of another magnet near the free end of a nail. What is observed? What is its reason?
Answer:
The free end of an iron nail repel. Because the free end of an iron nail becomes north pole by magnetic induction.

Question 14.
Complete the figure

Answer:

Question 15.
The pole of a magnet attracts an iron nail which has no magnetic power. Describe the work-ing behind this.
Answer:
The magnet attracts the iron nail brought near the pole of a magnet really as the result of magnetic induction. If the magnetic material reaches near the magnetic field of the magnet, an unlike pole is induced at its near end. The pole of permanent magnet is attract the newly formed unlike poles. That is why the magnetic pole attracts a magnetic material near it.

Question 16.
What are the factors that the attractive force of two magnetic poles depend on?
Answer:
The attractive force between the magnetic poles increases with increase in the strength of the pole and decreases with increase in the distance between the poles.

Question 17.
What is meant by atomic mag-nets?
Answer:
Each atom of a magnetic substance is an independent magnet. They are called atomic magnets.

Question 18.
What is meant by line of force (line of flux)?
Answer:
The line of force is the path that the north pole of a free magnetic needle would take around the bar magnet.

Question 19.
Examine the figure and mark the poles

Answer:

You can Download Diversity for Sustenance Questions and Answers, Summary, Activity, Notes, Kerala Syllabus 8th Standard Basic Science Solutions Chapter 13 help you to revise complete Syllabus and score more marks in your examinations.

Kerala State Syllabus 8th Standard Basic Science Solutions Chapter 13 Diversity for Sustenance

Diversity for Sustenance Textbook Questions and Answers

Diversity For Sustenance Kerala Syllabus 8th Chapter 13 Biosphere

Biosphere is the part of earth where life exists. Living world contains plants, animals, microorganisms, etc. Abiotic factors are also essential for the existence of living world. Sun is the ultimate source of energy in living world. Green plants convert light energy to chemical energy by photosynthesis.

Illustration (Text Book Page No:182)

Diversity For Sustenance Class 8 Kerala Syllabus Chapter 13 Question 1.
Discuss and complete the illustration given below suitably.

Diversity For Sustenance Pdf Kerala Syllabus 8th Chapter 13 Ecology

Ecology is the study of interrelationship of organisms among themselves and with their environment.

Basic Science Class 8 Chapter 13 Kerala Syllabus Chapter 13 Producers

Plants that perform photosynthesis are the producers.

Hss Live Guru Biology 8 Kerala Syllabus Chapter 13 Consumers

Organisms that directly or indirectly depend on green plants for energy are called consumers. Animals that directly depend plants are called primary consumers. Those dependent on primary consumers are the secondary consumers. The organisms depend on secondary consumers are called tertiary consumers.

Indicators (Text Book Page No: 183)

Hss Live Guru 8th Biology Kerala Syllabus Chapter 13 Question 1.
How do food chain and food web differ from each other?
Answer:
The chain of animals that eat and being eaten constitute food chain. But in nature different food chains are interrelated and this network is called food web.
Eg. Food Chain

8th Class Biology Notes Pdf Kerala Syllabus Chapter 13 Question 2.
Is a single organism involved in more than one food chain?
Answer:

• Same organism belongs to different food chains.
• Beneficial. No species increase or decrease beyond a level.

8th Class Physics Notes Kerala Syllabus Chapter 13 Question 3.
Is the possibility of an organism becoming food to more Is the possibility of an organism becoming food to more than one organism helpful to the existence of the food chain?
Why?
Answer:
If a particular species increase its number, the animals that forms its food get destroyed. It cause food scarcity and thus they themselves destroyed.

Diversity For Sustenance Notes Kerala Syllabus 8th Chapter 13 Question 4.
How does the variation in the number of a particular organism in the food chain affect the existence of other organisms?
Answer:
The number of an organisms decrease it adversely effects the existences of another group that depend them for their food. The increase and decrease in the number of organisms adversely affect the equilibrium of environments.

Hss Live Guru 8 Biology Kerala Syllabus Chapter 13 Trophic Level

Trophic level indicates the position of an organism in a food chain. Green plants belong to first trophic level. All food chains start from green plants. Herbivores are in II trophic level and Carnivores are included in III trophic level.

The Illustration (Text Book Page No: 184)

Basic Science For Class 8 Chapter 13 Question 5.
Did you read the note on trophic level?
Complete the illustration by including the organisms of the food web at various trophic levels
Answer:
Tertiary Consumers – Eagle, Mongoose
Secondary Consumers – Frog, Snake
Primary Consumers – Grasshopper, Rat
Producers – Grass, Paddy

Hsslive Guru Biology 8th Kerala Syllabus Chapter 13 Question 6.
Does the same organism occupy more than one trophic level?
Answer:
The same organism is included in different trophic levels as the complexity of food web increases.

Kerala Syllabus 8th Standard Chemistry Notes Chapter 13 Question 7.
Is there any possibility of a fifth trophic level?
Answer:
The number of trophic levels is an ecosystem is not constant. Even though in nature the food chains are not too long. This is to reduce the loss of energy during transmission.

Kerala Syllabus 8th Standard Physics Notes Chapter 13 Question 8.
How does the elimination of organisms from the higher trophic levels affect the ecosystem?
Answer:
The loss of organisms in higher levels cause tremendous increase in the number of organisms in the lower levels. It disrupt the equilibrium of environment.

Interactions in the Ecosystem

Many relations exist in nature. It maintains the equilibrium and stability of the ecosystem.
Food relations between organisms are good examples for these interactions.
Predation: One is benefitted. Other is harmed,
eg. Tiger and Deer.
Parasitism: One is benefitted. Other is harmed,
eg: Mango tree and Loranthus.
Competition: Both are harmed first. Later the winner is benefitted.
eg: Paddy and Weeds.
Mutualism: Both are benefitted
eg: Sea anemone and Hermit crab.
Commensalism: One is benefitted and the other is neither benefitted nor harmed.
eg : Mango tree and Vanda

Biodiversity

Biodiversity is the sum total of all the diverse species of organisms and their ecosystems (habitats)
Biodiversity has 3 different levels such as ecosystem diversity species diversity and genetic diversity.
Walter G. Rosen is the scientist who used the term ‘biodiversity’ for the first time.

Indicators (Text Book Page No: 186)

Hsslive Guru 8th Class Kerala Syllabus Chapter 13 Question 9.
Are all ecosystems alike in biodiversity?
Answer:
No.

Question 10.
Are all organisms seen in an ecosystem also seen in another ecosystem?
Answer:
Organisms adapted to the conditions of particular ecosystems. The physical and chemical structure of each ecosystem is different. So organisms seen in one ecosystem may not be present in another ecosystem.

Question 11.
What is the need for protecting natural ecosystems?
Answer:
Natural ecosystem are to be conserved for the existence and conservation of organisms. Ecosystems are the treasure houses of biodiversity. They provide innumerable services. Essential services, Ecological services, supporting services, and cultural services.

Indicators (Text Book Page No: 188)

Question 12.
Large scale destruction of ecosystems
Answer:
Birds are primary the victims of changes occurring in the ecosystem

Question 13.
Overexploitation of the natural resources
Answer:
The unwise interference of human beings destroys our ecosystem with rich biodiversity. If adversely affects the bird diversity in our locality. Many species of birds disappeared due to habitat loss. The pesticides like DDT, endosulfan used in agricultural field kills or drives away the birds that come
in search of food.

Conservation of Biodiversity

Conservation of organisms within their natural habitat is termed as in-situ conversation.
eg: Wildlife sanctuaries, National Parks, Community Reserves, etc.
Conservation of organisms outside their natural habitats is termed ex-situ conservation.
eg : Zoological garden, botanical garden, gene bank

Indicators (Text Book Page No: 183)

Question 14.
What is the scope of ex-situ conservation?
Answer:
It is possible to conserve the endangered animals by keeping them in specialized environment and by providing suitable conditions for reproduction. Rare species of plants can be conserved. Seeds, gametes, etc. can be collected and make we when necessary.

Question 15.
What is the significance of gene banks?
Answer:
Gene banks are research centers. Here special arrangements are these to collect seeds, gametes, etc. and to preserve them for long periods. Animals can be recreated when necessary.

Let US assess (Text Book Page No: 195) 

Question 16.
Phytoplankton – zooplankton – fish – seal – shark
a) In which trophic level is the secondary consumer of this food chain included?
b) Rewrite the food chain in such a way that the organism in the third trophic level figures in the second trophic level.
Answer:
a. In 3^rd trophic level.
b. algae → fish → duck

Question 17.
Find the odd one out from the following. Justify your answer.
a) Quagga, Malabar civet cat, Nilgiri Tahr, Lion-tailed macaque.
b) Eravikulam, Mathikettan shola, Periyar, Silent Valley
Answer:
a. Quaaga, Extinct
b. Periyar – Wildlife Sanctuary Others are national parks.

Question 18.
Examine the statements given below and rewrite if there are errors.
a) Extinct species are included in the Red Data Book.
b) WWF is an organisation working with the objective of protection of biodiversity.
c) Gene banks are included in in-situ conservation.
Answer:
In red data book endangered organisms are included
b. Right / True
c. Seed bank, sperm bank etc. are ex-situ conservation methods.

Diversity for Sustenance Additional Questions & Answers

Question 19.
Classify the following as producers and consumers.
Lizard, Planktons, Paddy, Calotes, Carrot, Grasshopper, Tortoise, Algae, Snake
Answer:

Producers	Consumers
Paddy	Lizard
Carrot	Calotes
Planktons	Grasshopper
Algae	Tortoise
	Snake

Question 20.
Find out suitable example for the animal relations mentioned.
i. Parasitism
ii. Mutualism
iii. Commensalism
Crops × Weeds
Mango tree × Vanda
Mango tree × Loranthus
Fish × Heron
Hermit crab × sea anemone
Answer:
i. Mango tree and Loranthus
ii. Hermit Crab – Sea anemone
iii. Mango tree and Vanda.

Question 21.
Complete the illustration Suitably

Answer:
a. Environmental / Ecological services
b. Cultural services
c. Food, Medicine
d. Nutrient Cycle, Pollination

Question 22.
Which are the different types of conservation of biodiversity?
Answer:
These are mainly two types.

1. In-situ conservation in which organisms are conserved within their natural environment
2. Ex-situ conservation in which animals are protected out their natural environment.

Question 23.
Classify the following into Ex-situ and In-situ.
(Zoological Gardens, Sacred Groves, Gene banks, Biosphere Reserves, Botanical Gardens, National parks)
Answer:

In-situ	Ex-situ
National parks	Zoological Gardens
Sacred Groves	Gene Banks Botanical
Biosphere Reserves	Gardens.

Question 24.
Expand the following terms.
Answer:
JNTBGRI – Jawaharlal Nehru Tropical Botanic Garden and Research Institute.
MBG – Malabar Botanical Garden RGCB – Rajiv Gandhi Centre for Biotechnology.

Question 25.
Why do all the food chains start from green plants?
Answer:
The basis of all food chains is the plants. They are the producers. These are eaten by the herbivores which in turn are eaten by the carnivores.

Question 26.
The members at the successively higher levels are lesser in number and larger in size in a food chain. What about their body weight? What would be the reason for that?
Answer:
In the successively higher levels in the food chain the number of consumers decreases and the size of their body increases. The number of producers will be very large. The number of animals which feed on them is less in number. But their body size increases.

Question 27.
Hay → Horse
Paddy → Fowl → Fox
Phytoplankton → Tadpole → Fish → Man
Grass → GrasshopperFrog → Snakes Vulture
Examine the food chain given above and classify them as primary consumers, secondary and tertiary consumers.
Answer:
Producers: Hay, Paddy, Phytoplankton, Grass
Primary consumer: Horse, Fowl, Tadpole, Grasshopper
Secondary consumers: Fox, Fish, Frog, Snake
Tertiary consumers: Vulture, Man

Question 28.
What will happen if the number of herbivores increases?
Answer:
If the number of herbivores increase they will eat away all the grass and shrubs and they will have to face shortage of food. The destruction of grass and shrubs will cause soil erosion and the top fertile soil will be washed away.

Question 29.
Animals which are facing extinction.
Answer:

• Wild goat
• Musk deer
• Indian wild Ass
• Lion-tailed Monkey
• Lion
• Rhinoceros
• The large Indian Bustard
• Tiger
• Kashmir deer
• Himalayan Tig
• Silver owl
• Panda

You can Download Why Classification? Questions and Answers, Summary, Activity, Notes, Kerala Syllabus 8th Standard Basic Science Solutions Chapter 12 help you to revise complete Syllabus and score more marks in your examinations.

Kerala State Syllabus 8th Standard Basic Science Solutions Chapter 12 Why Classification?

Why Classification? Textbook Questions and Answers

Classification

Classification is the grouping of organisms on the basis of similarities and differences. Classification using suitable criteria makes the study of organisms more easy. Many criteria are used in classification.
Eg: size, beauty, speed, type of teeth, claws, etc.

Taxonomic Keys

Scientific indicators used to recognize and classify plants and animals are called Taxonomic keys. Dichotomous keys is the most popular among these. Each indicator contains 2 options for selection. By selecting the characteristic feature of the organism to be identified it can be recognized and classified.

Indicators (Text Book Page No: 170)

Why Classification Class 8 Kerala Syllabus Chapter 12 Question 1.
Peculiarity of dichotomous keys
Answer:
Dichotomous key is the most popular among these. Each indicator contains 2 options for selection. By selecting the characteristic feature of the organism to be identified it can be recognized and classified.

Why Classification Kerala Syllabus Chapter 12 Taxonomy

Taxonomy is the branch of science that deals with the identification and classification of organisms according to similarities and differences. Organisms are given scientific names. Carl Linnaeus laid foundation stone for classification. In all organism that including human beings are placed in different levels of classification. It was scientist named carl Linnaeus who fixed taxonomic hierarchy and provided a scientific base for classification. Hence he is known as the father of taxonomy.

Scientists and their Contribution to Taxonomy

Aristotle:

Father of Biology Classified animals as red-blooded and non-red blooded

Theophrastus:

Father of Botany Grouped Plants as animals, biennials, and perennials

Charaka:

Father of Ayurveda Author of ‘Charaka Samhita’

John Ray:

– Used the term ‘Species’ for the first time
– Recorded more than 18000 plants in his book ‘Historia Generalis Plantarum’

Carls Linnaeus:

– Father of Modern Taxonomy.
– Suggested different levels of Classification
– Introduced Binomial Nomenclature

Why Classification Notes Kerala Syllabus Chapter 12 Indicators (Text Book Page No: 173)

Hss Live Guru Biology 8 Kerala Syllabus Chapter 12 Question 2.
Which are the organisms included in kingdom Animalia?
Answer:
Cockroach, Butterfly, Bird, Rabbit, Cat, Tiger, Lion, bear

Why Classification Class 8 Notes Kerala Syllabus Chapter 12 Question 3.
Which organisms are excluded at each consecutive level? Why?
Answer:

• Eliminated from Phylum Chordates — Butterfly, Cockroach
  Reason — Animals with vertebral columns alone are included in the phylum chordates.
• Eliminated from Class Mammalia
  — Bird (Pigeon) Reason — Animals that give birth to young ones alone included in this group.
• Eliminated from the order Carnivora — Rabbit
  Reason — Carnivores alone included in this order.
• Eliminated from the family Felidae — Bear
  Reason — It does not have retractile claws.
• Eliminated from the Genus Felis — Lion, tiger
  Reason — Animals having small body and without roaring sound are included.
• Eliminated from the Species domestic — Wild Cat
  Reason — It has the basic features of cat

Basic Science Class 8 Chapter 12 Solution Kerala Syllabus Chapter 12 Question 4.
At what levels of this illustration can humans be included?
Answer:
Man can be included in Class Mam-malia and Phylum Chordata.

Binomial Nomenclature

Binomial nomenclature is the scientific naming of organisms. Scientific name consists of two words. First word indicates genus and second word indicates species. Scientific name of man – Homo sapiens. Earlier two-kingdom classification was in practice. Accordingly, the organisms were broadly classified into planate and anemia. Later Rober. H. Whittaker classified organisms into 5 Kingdoms.
Eg : Monera, Protista, Fungi, Plantae, Animalia.
Another Scientist Carl Vaus added ‘domain’ above kingdom and expanded it into 6 kingdom classification.

Indicators (Text Book Page No: 176)

Class 8 Basic Science Chapter 12 Kerala Syllabus Chapter 12 Question 5.
Limitations of two-kingdom classification.
Answer:
Bacteria, Fungus, etc were not inclu­ded in two kingdom classification.

Hss Live Guru 8th Physics Kerala Syllabus Chapter 12 Question 6.
Possibilities of five kingdom classification.
Answer:
In five kingdom classification bacteri­a, amoeba, fungus, plants, and animals were included in separate kingdoms according to their characteristics.

8th Std Physics Notes Kerala Syllabus Chapter 12 Question 7.
Circumstances that led to the formulation of six kingdom classification.
Answer:
In ancient times knowledge regarding the characteristics of micro organ­isms was limited. It was found out that the cell structu­re and physiology of archaebacteria belongs to kingdom monera are quite different from other bacteria. Hence kingdom monera was divided into two kingdoms – Archae and Bacteria. Be­sides another level namely ‘domain’ was added above kingdom. Thus 6 king­dom classification came into existence

8th Standard Biology Kerala Syllabus Chapter 12 Question 4.
Completing the table (Text Book Page No: 177)

Answer:

Domain	Eukarya
Kingdom	Animalia
Phylum	Chordata
Class	Mammalia
Order	Primates
Family	Hominidae
Genus	Homo
Species	Sapiens

Indicators (Text Book Page No: 178)

Basic Science Class 8 Chapter 12 Kerala Syllabus Question 8.
What are the peculiarities of virus?
Answer:
Viruses have no specific cell structure. Genetic material and a protein sheath alone are present. It is difficult to destroy them. They live only in living cells. They are dead or inactive outside the cell. It multiplies inside the host cell and destroys it.

Hss Live Guru 8 Biology Kerala Syllabus Chapter 12 Question 9.
Can virus be included in any of the classification methods we have discussed earlier? Why?
Answer:
As viruses have no cellular structure, it is not possible to include in any of the classifications mentioned.

Let US assess (Text Book Page No: 179) 

Basic Science For Class 8 Chapter 12 Kerala Syllabus Question 10.
Identify the word pair relation and fill in the blanks
a. Five kingdom classification: Robert H.Whittaker
Six kingdom classification :
b. Charaka: Charaka Samhita
John Ray
Answer:
a. Carl Vaus
b. Historia Generalis Plantarum

Kerala Syllabus 8th Standard Biology Notes Chapter 12 Question 11.
Hints about some organisms are given below. Name the
kingdom to which these organisms belong:
a. Multicellular heterotrophic organisms with a nucleus and capacity for locomotion.
b. Multicellular, heterotrophic, non-motile organisms with a nucleus.
c. Unicellular organisms with a nucleus.
d. Multicellular, autotrophic, non-motile organisms with a nucleus.
Answer:
a. Animals
b. Fungi
c. Amoeba
d.Plants

Kerala Syllabus 8th Standard Chemistry Notes Chapter 12 Question 12.
Write from the table the name of the organism which has more resemblances with tiger. Give explanations for your answer.

Answer:
Lion having the scientific name Pantheraleo.
Lion and Tiger belongs to same Genus ‘Panthera’

Why Classification? Additional Questions and Answers

Basic Science Class 8 Ch 12 Kerala Syllabus  Question 13.
Identify the word pair relation and fill the blanks.
a. 2 Kingdom Classification: Carls Linnaeus:: 5 kingdom Classification: …………….
b.Mushrooms: Fungi:: Bacteria: ……………..
c. Aristotle – Father of Biology Carls Linnaeus – …………….
d. Golden shower: Cassia fistula::…………..: Corvus splendens
e. Charaka: Father of Ayurveda::……………: Father of Botany
Answer:
a. R H Whittaker
b. Monera
c. Father of Taxonomy
d. Crow
e. Theophrastus

Hss Live Guru 8th Biology Kerala Syllabus Chapter 12 Question 14.
2. Identify the odd one and write the characteristic features of others.
a. Lion, Tiger, Rabbit, Cat.
b. Genus, Order, Carl Linnaeus, Phylum.
Answer:
a. Rabbit – Others including order Carnivora
b. Carl Linnaeus – He is the Father of Modern Taxonomy. Others are different levels of classification.

Question 15.
Which organism is most suit¬able for the following indicators (amoeba, bacteria, virus, Fungus)
1. Lives only in living cell
2. Pathogen
3. Only genetic material and a protein covering.
Answer:
Virus

Question 16.
Find out the scientists suitable to the statements given.
i. Author of Charaka Samhitha
ii. Author of Historia Generalis Plantarum
iii. Father of Modern Taxonomy
iv.Father of Biology
Answer:
i. Charaka
ii. John ray
iii. Carl Linnaeus
iv. Aristotle

Question 5.
Complete the table

Answer:

• Elephas Maximus / Elephas Indicus
• Pavo Cristatus
• Canis Familiaris
• Hibiscus Rosasinensis
• Azadiracuta Indica
• Oryza sativa

Question 17.
What are limitations in the system of classification of Carl Linnaeus?
Answer:
Some lower organisms share the characters of both animals and plants. So it is difficult to recognize them as plants or animals. Linnaeus considered only plants and animals for his classification. Microscopic organisms like bacteria, fungus, protozoa, etc were not included either in plant kingdom or in animal kingdom. Certain animals which were included in the classification of Linnaeus show characters of both the animal and plant kingdoms. Eg: Euglena protozoan shows locomotory movements like animals, but it contains chlorophyll like plants.

Question 18.
7. Hints about some organisms are given below. Name the kingdom to which these organisms belong.
a. Multicellular heterotrophic organisms with a nucleus and capacity for locomotion.
b. Multicellular heterotropic, non-motile organisms with a nucleus.
c. Unicellular organisms with a nucleus.
d. Multicellular, autotroph, non-motile organisms with a nucleus
Answer:
a. Animalia
b. Fungi
c. Protista
d. Plantae

Question 19.
Write the scientific name of following animals and plants. Coconut, paddy, wheat, crow, mango, grapes
Answer:
Coconut – Cocos nucifera
Paddy – Oryza sativa
Wheat – Triticum aestivum
Crow – Corvus splendens
Mango – Mangifera indica
Grapes – Vitis vinifera

Question 20.
What are two important characters of species?
Answer:
1. Species is a group of organisms that can freely interbreed to produce fertile offsprings.
2. A group of organisms that closely resemble each other in structure biochemical makeup and external characteristics but which are genetically different. In one species there may be subspecies.

Question 21.
The method of classification adopted by Whittaker is much better than the method adopted by Carl Linnaeus the father of the science of classification. What is your response to this statement?
Answer:
The classification of Linnaeus had only two kingdoms, plants, and animals. He did not consider bacteria, protozoa, fungus, etc. Certain characters of animals considered by Linnaeus for classification are found in both the kingdoms, eg. photosynthesis found in plants is seen in some animals like Euglena. Certain characters of animals can be seen in plants also, eg certain types of algae. But Whittaker adopted the method of having five kingdoms including protozoa and bacteria.

• Monera,
• Protista
• fungi
• Plantae
• animalia

Question 22.
Bacteria does not have a well defined Nucleus. Viruses are also like Bacteria. Why is it not possible to include viruses under Monera.
Answer:
Viruses exhibit living nature only when they enter the host cells. On other occasions, they do not exhibit living nature. But organisms in Monera are not like that.

Question 23.
How do the levels of classification of plants made by Carl Linnaeus differ from the levels of classification of Animals?
Answer:
Not much differences are there. In the place of ‘Order’ in animal classification, plant classification has series. And in the place of ‘Phylum’ in animal classification, plant classification has ‘Division’.

Question 24.
Find the level of classification and complete the given table.

Answer:
1. Kingdom
2.Phylum Chordata
3. Mammalia
4. Mammalia
5. Species

Question 25.
Cell is the smallest unit of life. But there are certain organisms that live without cell too. Analyze this statement.
Answer:
Life is not possible without a cell. Viruses do not have cells. As it is so, it does not have life when it outside a living cell. As it enters a living cell, it will show the features of life forms. It makes use of the components of the host cell and continues to live. Though it does not have a cell, it can continue its life only after entering a host cell and by making use of its components.

Question 26.
Observe the given statement, and write correct answer if you find false statements.
a. Aristotle is the Father of Biology.
b. John Ray is the Father of Botany.
c. Carl Linnaeus used the term ‘species’ for the first time.
d. Charaka proposed binomial nomenclature.
Answer:
a. True
b. False, Theophrastus
c. False, John Ray
d. False, Carl Linnaeus

Question 27.
What is the relationship between taxonomic keys and dichotomous key?
Answer:
Taxonomic keys are scientific indicators used to identify and classify plants and animals. Dichotomous keys is one of the popular taxonomic keys.

You can Download Equal Triangles Questions and Answers, Activity, Notes, Kerala Syllabus 8th Standard Maths Solutions Chapter 7 help you to revise complete Syllabus and score more marks in your examinations.

Kerala Syllabus 8th Standard Maths Solutions Chapter 7 Ratio

Area of Quadrilaterals Text Book Questions and Answers

Ratio Chapter Class 8 Kerala Syllabus Question 1.
In a regular polygon, the ratio of the inner and outer angle is 7 : 2. What is each angle? How many sides does the polygon
Solution:
Let the inner angle be 7x and the outer angle 2x .
Inner angle + outer angle = 180°
7x + 2x = 180°
9x = 180°
x = 180 ÷ 9 = 20°
Inner angle = 7x = 7 × 20 = 140°
Outer angle = 2x = 2 × 20 = 40°
Sum of the outer angles of a polygon of n sides is 360°. Since it is a regular polygon, the outer angles are equal,
n × 40 = 360°

Number of sides of the polygon = 9

Hsslive Maths Class 8 Kerala Syllabus Question 2.
The number of girls and boys in a class are in the ratio 7 : 5 and there are 8 more girls than boys. How many girls and boys are there in this class?
Solution:
Let the number of girls be 7x and the number of boys be 5x ,
Difference = 7x – 5x = 2x

Number of girls = 7x = 7 × 4 = 28
Number of boys = 5x = 5 × 4 = 20

Hsslive Class 8 Maths Kerala Syllabus Question 3.
Blue and yellow paints are mixed in the ratio 2 : 5 to make a new colour. 6 litres more of yellow 1 than blue is taken. How many litres of each is mixed?
Solution:
Let the measure of blue paint be 2x and yellow paint be 5x .
Their difference = 5x – 2x = 3x
3x = 6
x = 2
Quantity of blue paint = 2x = 2 × 2 = 4 litre
Quantity of yellow paint = 5x = 5 × 2 = 10 litre

Hsslive Guru 8th Class Maths Kerala Syllabus Question 4.
There are four right triangles, the ratio of perpendicular sides being 3 : 4 m each. One more fact about each is given below. Find the lengths of the sides of each triangle.
i. The difference in the lengths of the perpendicular sides is 24 metres.
ii. The hypotenuse is 24 metres.
iii. The perimeter is 24 metres.
iv. The area is 24 square metres.
Solution:
i. Let the perpendicular sides be 3x and 4x

The difference between the perpendicular sides be,
4x – 3x =x
x = 24
Sides are, 3x = 3 × 24 = 72 m
4x = 4 × 24 = 96 m
5x = 5 × 24 = 120 m

ii. Hypotenuse = 5x = 24

Perpendicular sides 3x = 3 × 4.8 = 14.4 m
4x = 4 × 4.8 = 19.2 m

iii. Perimeter = 3x + 4x + 5x = 12x
12x = 24
x = 2
Sides are, 3x = 3 × 2 = 6m
4x = 4 × 2 = 8 m
5x = 5 × 2 = 10 m

iv. Area = 1/2 × 3x × 4x = 6x ²
6x ² = 24
x ² = 4; x = 2
Sides are, 3x = 3 × 2 = 6m
4x = 4 × 2 = 8m
5x = 5 × 2 = 10 m

Textbook Page No 137

8th Std Maths Guide Kerala Syllabus  Question 5.
Acid and water are mix ed in the ratio 4 : 3 to make a liquid. On adding 10 more litres of water, the ratio changed to 3 : 1. How many litres of acid and water does the liquid contain now?
Solution:
Let the volume of acid be 4x and volume of water be 3x volume of acid on adding 10 more litres of acid = 4x + 10 litres
present ratio = 3 : 1
4x + 10 : 3x = 3 : 1
3 × 3x = 1 × (4x + 10)
9x = 4x + 10
9x – 4x = 10 ; 5x = 10
x = 2
Volume of acid in the original mix ture = 4x = 4 × 2 = 8 litres
Volume of water in the original mix ture = 3x = 3 × 2 = 6 litres
Volume of acid in the present mix ture = 8 + 10 = 18 litres
Volume of water in the present mix ture = 6 litres

Hss Live Maths Class 8 Kerala Syllabus Question 6.
Two angles are in the ratio 1 : 2. On increasing the smaller angle by 6° and decreasing the larger angle by 6°, the ratio changed to 2 : 3. What were the original angle?
Solution:
Let x be the smaller angle and 2x be the larger angle,
x + 6 : 2x – 6 = 2 : 3
2(2x – 6) = 3 (x +6)
4x – 12 = 3x + 18
4x – 3x = 18 + 12 = 30; x = 30
Original smaller angle = x ° = 30°
Original larger angle =2x ° = 6o°

Hss Live Guru 8th Maths Kerala Syllabus Question 7.
The sides of a rectangle are in the ratio 4 : 5.
i. By what fraction should the shorter side be increased to make it a square?
ii. By what fraction should the longer side be decreased to make it a square?
Solution:
Let 4x be the smaller side and 5x be the larger side,
i. Let y part of a shorter side be added breadth after adding = 4x + 4xy = 4x (1 + y)
Ratio of breadth and length of a square = 1 : 1
so present ratio
4 × (1 + y) : 5x = 1 : 1
1 × 4x (1 + y) = 5x × 1
4(1 + y) = 5

On adding \(\frac{1}{4}\) part of the original breadth, it can be made into square,

ii. Let y part of the longer side be substracted length after subtracting = 5x – 5xy
= 5x (1 – y)
As the present ratio is 1 : 1
5x (1 – y) : 4x = 1 : 1
1 × 5x (1 – y) = 1 × 4x
5 (1 – y) = 4

On subtracting \(\frac{1}{5}\) part of the original length, it can be made into square.

Hss Live Guru 8 Maths Kerala Syllabus Question 8.
Two quantities are in the ratio 3 : 5
i. If the smaller alone is made four times the original, What would be the ratio?
ii. If the smaller is doubled and the larger is halved, What would be the ratio?
Solution:
i. Let 3x be the smaller side and 5x be the larger side,
4 times the smaller = 4 × 3x = 12x
present ratio = 12x : 5x = 12 : 5

ii. Double the smaller = 2 × 3x = 6x

Kerala Syllabus 8th Standard Maths Notes Question 9.
i. The capacities of two bottles are in the ratio 3 : 4. The smaller bottle was filled twice and the larger bottle was filled and emptied into a vessel. Twice the smaller and half the larger was emptied into another. What is the ratio of the quantities of water in the two vessels?

ii. In the problem, what is the capacities of the bottles are in the ratio 4 : 7?
Solution:
i. Let the capacity of the smaller bottle = 3x
the capacity of the larger bottle = 4x
Volume of water when the smaller bottle is filled twice = 2 × 3x = 6x
Volume of water when the larger bottle is filled once = 4x
Total volume now = 6x + 4x = 10x
Volume of the water when the smaller bottle is filled twice = 6x
Volume of water when larger bottle is filled half = \(\frac{4 x }{2}\) = 2x
Total volume now = 6x + 2x = 8x
Ratio of the quantities of water = 10x : 8x , = 10 : 8 = 5 : 4

ii. Ratio of capacities of the bottle = 4 : 7
Let the capacity of the smaller bottle = 4x
the capacity of the larger bottle = 7x
Volume of water when the smaller bottle is filled twice = 2 × 4x = 8x
Volume of water when the larger bottle is filled once = 7x
Total volume now = 8x + 7x = 15x
Volume of the water when the smaller bottle is filled twice = 8x
Volume of water when larger bottle is filled half = \(\frac{7 x }{2}\)

= 30 : 23 (multiplied by 2)

8th Std Maths Notes Kerala Syllabus Question 10.
The breadth and length of two rectangles are in the ratio 2 : 3. In another rectangle, whose breadth is 1 cm less and length is 3 cm less than those of the first, this ratio is 3 : 4. Calculate the breadth and length of both rectangles.
Solution:
Ratio between the breadth and length of the first rectangle = 2 : 3
Breadth of the first rectangle = 2x
Length of the first rectangle = 3x
Breadth of the second rectangle = 2x – 1
Length of the second rectangle = 3x – 3
Ratio between the breadth and length = 3 : 4
so, (2x – 1) : (3x – 3) = 3 : 4
3 (3x – 3) = 4 (2x – 1)
9x – 9 = 8x – 4
9x – 8x = -4 + 9
x = 5
Breadth of the first rectangle = 2x = 2 × 5 = 10cm
Length of the first rectangle = 3x = 3 × 5 = 15 cm
Breadth of the second rectangle = 2x – 1 = 10 – 1 = 9 cm
Length of the second rectangle = 3x – 3 = 15 – 3 = 12 cm

Textbook Page No 141

Hsslive Guru Class 8 Maths Kerala Syllabus Question 11.
Johny invested 50000 rupees, Jaleel 40000 rupees and Jayan 20000 rupees to start a business together. They got 3300 rupees as profit in a month, which they divided in the ratio of their investments. How much did each get ?
Solution:
Ratio of the investment = 50000 : 40000: 20000 = 5 : 4 : 2
Profit of one month = 3300 rupees

Kerala Syllabus 8th Standard Notes Maths Question 12.
The capacities of three water tanks are in the ratio 2 : 3 : 5. The smallest of them can hold 2500 litres. How many litres can the other two hold ?
Solution:
Ratio of the capacities = 2 : 3 : 5
Let the capacities be 2x , 3x , 5x
Quantity of water in smaller tank = 2x = 2500
x = 1250 litres
Capacity of second tank = 3x = 3 × 1250 = 3750 litres
Capacity of third tank = 5x = 5 × 1250 = 6250 litres

Maths Guide For Class 8 Kerala Syllabus Question 13.
The angles of a triangle are in the ratio 1 : 3 : 5. How much is each angle?
Solution:

Class 8 Maths Notes Kerala Syllabus Question 14.
The outer angles of triangle are in the ratio 5 : 6: 7. What are the angles ?
Solution:
Sum of outer angle = 360°
Let the angles be 5x , 6x , 7x
5x + 6x + 7x = 360°
18x = 360°
x = 20°
Angles are = 5x =5 x 20 = 100°
6x = 6 × 20 = 1200
7x = 7 × 20 = 140°

8th Standard Maths Notes Kerala SyllabusQuestion 15.
The sides of a triangle are in the ratio 2 : 3 : 4. The longest side is 20 cm more than the shortest side. Calculate the length of all three sides.
Solution:
Let sides be 2x , 3x , 4x then,
Since the longest side is 20 cm more than the shortest side,
4x = 2x + 20, 4x – 2x = 20
2x = 20
x = 10
First side = 2 × 10 = 20 cm
Second side = 3 × 10 = 30 cm
Third side = 4 × 10 = 40 cm

Class 8 Chapter 7 Maths Kerala Syllabus Question 16.
A box contains beads of three colors. Black beads and white beads are in the ratio 3 : 5. White and red beads are in the ratio 2 : 3. What is the ratio of all three colors ?
Solution:
Black beads : White beads: Red beads

Hsslive Guru 8 Maths Kerala Syllabus Question 17.
The length, breadth and height of a rectangle block are in the ratio 3 : 2 : 5 and its volume is 3750 cubic centimetres. Calculate the length, breadth and height.
Solution:
Let breadth be 3x , length be 2x and height be 5x , then
3x × 2x × 5x = 3750
30 × 3 = 37
x = 5
Breadth = 3x = 3 × 5 = 15 cm
Length = 2x = 2 × 5 = 10 cm
Height = 5x = 5 × 5 = 25 cm

Additional Questions And Answers

Hss Live Guru Maths 8th Kerala Syllabus Question 1.
Sides of a triangular plot are in the ratio 3 : 5 : 7. Perimeter of the plot is 150 meter. Find the length of the sides.
Solution:
Perimeter = 150 m

= 30 m, 50 m, 70 m

Question 2.
The denominator and numerator of fraction are in the ratio 3 : 1. If \(\frac{1}{2}\) part of the numerator is added to it, prove that the ratio becomes 2 : 1.
Solution:

Ratio between denominator and numerator, when \(\frac{1}{2}\) part of the numerator is added to it, then the ratio is 6 : 3 = 2 : 1

Question 3.
Arun, Varun and Hari bought two packet of sweets, 245 in all. The ratio of the number of sweets Arun took to the number of sweets Varun took is 3 : 4. The ratio of the number of sweets Varun and Hari took is 6 : 7
How many sweets did each take?
Solution:

Question 4.
In a goat farm, the ratio of the number of goats which give milk to the number of goats which don’t is 6 : 2. The number of goat which don’t give milk is 160. How many goats do give milk? And how many goats are there in all?
Solution:
Ratio of the number of goat which give milk to the number of goat which don’t = 6 : 2
We have to find how many times the number of goat which don’t give milk is the number of goats which give milk is \(\frac{6}{2}\) times
that the number of goats which don’t give milk.
Therefore the number of goats which give milk \(160 \times \frac{6}{2}=480\)
Total number of goats = 160 + 480 = 640

Question 5.
Length and breadth of a rectangle are in the ratio 5 : 3. How many parts of the length of this rectangle is to be deducted so as to get the ratio of the length and breadth of the new rectangle is 7 : 6?
Solution:
5 : 3 = 10 : 6
If \(\frac{3}{10}\) part of 10 is deducted from it, the ratio is 7 : 6
That is \(\frac{3}{10}\) part of the length is deducted from it, the ratio is 7 : 6

Question 6.
In a school, the ratio of the number of boys to the number of teachers 2 : 3; and the ratio of the number of teacher to the number of girls is 4 : 5. What is the ratio of the number boys to girls.
Solution:
boys : teacher : girls

Question 7.
The ratio between the number of boys and girls in a college is 8 : 5. If the number of girls is 800, find the total number of students.
Solution:
Let the number of boys = 8x
Let the number of girls = 5x
5x = 800
x = 800 ÷ 5 = 160
Number of boys = 8 × 160 = 1280
Total number of students = 800 + 1280 = 2080

Question 8.
The sides of a triangle are in the ratio 3 : 5 : 7. Its smallest side is 28 cm less than the largest side. Find the sides of the triangle.
Solution:
Ratio of the sides of the triangle = 3 : 5 : 7
3x = 7x – 28
7x – 28 = 3x
4x = 28
x = 28 ÷ 4
Smallest side = 3 × 7 = 21 cm
Second side = 5 × 7 = 35 cm
Largest side = 7 × 7 = 49 cm

Question 9.
To make a colour, red, blue and green paints mixed in the ratio 1 : 2 : 4. How much quantity red and green are needed for 10 bottle of blue paint?
Solution:
Let red paint be 1x bottle, blue paint
2x bottle and green paint 4x
2x = 10 x = 10 ÷ 2 = 5
Red paint needed = 1 × 5 = 5 bottles
Green paint needed = 4 × 5 = 20 bottles.

Question 10.
In a 50 litre mixture of milk and water, milk and water are in the ratio 3 : 2. How much more milk should be added to it to make the ratio as 3 : 1.
Solution:
Let the measure of milk = 3x litre and
that of water = 2x litre.
3x + 2x = 50, 5x = 50
x = 50 ÷ 5 = 10
Milk = 3 × 10 = 30 litres
Water = 2 × 10 = 20 litres
Let k more litre of milk is added to make the ratio 3 : 1
Then 30 + k : 20 = 3 : 1
30 + k = 60, k = 60 – 30 = 30
Measure of milk to be added = 30 litres

Question 11.
The length and breadth of a rectangle are in the ratio 8 : 5. The length is 9 centimetres more than the breadth. What are the length and breadth of the rectangle?
Solution:
Let the length of the rectangle = 8x and breadth = 5x
Their difference = 8x – 5x = 3x
This is given as 9 m, 8x – 5x = 9
3x = 9, x = 9 ÷ 3 = 3
∴ Length of the rectangle = 8 × 3 = 24 cm
Breadth of the rectangle = 5 × 3 = 15 cm

Question 12.
In a concrete, cement and sand are mixed in the ratio 4 : 3. Prove that double the quantity of cement should be added to it to make the ratio 4 : 1.
Solution:
cement : sand = 4 : 3
Let cement = 4x and sand = 3x .
Double of cement = 2 x 4x = 8x ,
Quantity of cement now = 4x + 8x = 12x
Quantity of sand = 3x
Their ratio now = 12x : 3x
= 12 : 3 (divided by x)
= 4 : 1 (divided by 3)
That is if double the quantity of cement is added, the ratio will become 4 : 1.

Question 13.
Ratio of the number of red beads and blackheads in a box is 6 : 5. If the number of red beads is 4 more than the number of black beads find the number of red beads and black beads in the box.
Solution:
Let the number of red beads = 6x
Number of black beads = 5x
6x – 5x = 1x ; = 6x – 5x = 4
This is given as 4. ∴ x = 4
Number of red beads = 6 × 4 = 24
Number of black beads = 5 × 4 = 20

Question 14.
The ratio of the number of boys to the number of girls in a school is 14 : 15. There are 27 more girls than boys. How many girls are there in this school? How many boys?
Solution:
Ratio of the number of boys to the number of girls = 14 : 15
Let girls be 15x & boys be 14x
Their difference = 15x – 14x
= x = 27
Number of girls = 15x = 15 × 27 = 405
Number of boys = 14x = 14 × 27 = 378

Question 15.
State that if the sides of a triangle are in the ratio 3 : 4 : 5, then it is a right angled triangle. If perimetre is 36 cm, then find the length of the sides?
Solution:
Sides are 3x , 4x and 5x

Square of two sides are equal to the square of the third side. Therefore, it is a right angled triangle.

Question 16.
Ratio of cement, sand and gravel in a concrete mixture are in the ratio 1 : 3 : 4. If 80 kilogram of mixture is to be prepare, what quantity of cement, sand and gravel are to be taken?
Solution:
Let quantity of cement = x,
Quantity of sand = 2x,
Quantity of gravel = 4x
x + 3x + 4x = 80
8x = 8o ⇒ x = 10
quantity of cement = x = 10 kg
quantity of sand = 3x = 3 × 10 = 30 kg
quantity of gravel = 4x = 4 × 10 = 40 kg

Question 17.
Did the sides of a triangle be in the ratio 3 : 5 : 8 ? Why ?
Solution:
Sides are 3x, 5x and 8x .
3x + 5x = 8x
here sum of two sides is equal to the third side.
But sum of two sides should be greater than the third side. So the given sides
3x, 5x and 8x are not the sides of a triangle.
Therefore the ratio 3 : 5 : 8 cannot be the sides of a triangle.

Question 18.
In ∆ ABC, AB : BC = 2 : 3, BC : CA = 4 : 5, then find AB : BC : CA.
Solution:

Question 19.
One side of triangle given below is 12 cm. P is the midpoint of BC. Find the ratio of areas between ∆ ABC and ∆ APC

Solution:

Question 20.
Area of a rectangle is 2400 sq.cm. If length and breadth are in the ratio 8 : 3, find length and breadth? If length and breadth are increased by 20 cm, then find the ratio between length and breadth
Solution:
Length = 8x
Breadth = 3x

length = 8 × 10 = 80,
Breadth = 3 × 10 = 30
When length and breadth are increased by 20, then length = 100;
Breadth = 50
length : breadth = 2 : 1