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Kerala State Syllabus 8th Standard Basic Science Solutions Chapter 17 Fibres and Plastics
We have variety of substances around us for improving our lifestyle. The natural resources are utilised to produce a variety of modern materials.
Fibres And Plastics Class 8 Kerala Syllabus Polymers
Cotton. Silk, jute, wool, rubber etc are the molecules belonging the group of polymers. Polymers are macromolecules formed by the combination of large number of simple molecules called monomers. Fibres are the polymers suitable for the manufacture of strong threads. Plastics are the polymers which can be moulded into different shapes. Rubber is an elastic polymer.
Manmade polymers
In order to overcome the demerits like less availability, less durability etc several synthetic polymers have been prepared through chemical methods. Synthetic threads have demerits too. Some of them are low aeration, low ability to absorb water, high inflammability etc
Basic Science Class 8 Chapter 17 Kerala Syllabus Plastic
These are the substances that changed the very face of human life which are having different properties.
Thermoplastics and thermosetting plastics
The plastic that gets softened on heating and hardened on cooling is thermoplastics. The plastic which remains soft when heated during its manufacture, and gets hardened permanently on cooling is thermosetting plastics.
Plastics and Pollution
Even though plastics are very useful substance, the careless use and misuse lead to environmental pollution. Plastics give many benefits to mankind. Forest conservation, household utility etc are some of the benefits. There are many ways to reduce pollution due to plastics. Some of them reduce the use of dispo¬sable plastics, reduce; the overuse of plastic materials, use other material like glass, ceramic materials instead of plastic etc.
Fibres and Plastics Textbook Questions and Answers
Basic Science For Class 8 Chapter 17 Kerala Syllabus Questions 1.
Polymers are macromolecules formed by the combination of many monomers.
a. How are polymers classified?
b. Classify the following:
Cotton, Wool, Nylon, Silk, Terylene, Jute, Polyester
Answer:
a. i. On the basis of its formation as natural and man-made.
ii. On the basis of structure as linear branches chain, cross-linked chain
iii. On the basis of process as addition polymer and condensation polymer.
iv. On the basis of molecular strength as fibres and plastics
b. Natural: wool, silk, jute, cotton Man-made: Nylon, Terylene, Polyester
Kerala Syllabus 8th Standard Physics Notes Questions 2.
Some monomers and polymers are given in the following table:
| Monomer | Polymer |
| Ethene | Polyethene |
| Propene | Polypropene |
| Styrene Vinyl | Polystyrene |
| chloride | Polyvinyl chloride |
a. What is meant by the terms ‘monomer’ and ‘polymer’?
b. What is the common system of nomenclature of polymers?
Analyse the table and find out.
Answer:
a. Monomer: A Simple molecule having a particular structure
Polymer: Macromolecules formed by combination of large number of monomers.
b. Add the word ‘poly’ before the name of monomer.
Kerala Syllabus 8th Standard Chemistry Notes Question 3.
Natural fibres and synthetic fibres are used in the field of textile manufacturing.
a. Compare their merits and demerits and tabulate.
b. Which of these clothes is most suited for the following situations? Give reason.
i. While cooking in the kitchen
ii. To wear during summer
Answer:
a. Merits:
- Comfortable to wear
- Not inflammable
- Ability to absorb water
- High aeration
Demerits:
- Less available
- Less durability
- Wrinkle easily
- Cannot dry easily on getting wet
b. Natural fibres:- Because they are not inflammable, have ability to absorb sweat, high aeration
8th Class Biology Notes Pdf Kerala Syllabus Question 4.
You know what thermoplastics and thermosetting plastics are.
a. Which of these plastics cannot be recycled?
b.You might have noticed that those who collect old plastics do not accept certain type of plastic articles. What are they? What may be the reason for this?
Answer:
a. Thermoplastic
b. Thermosetting plastic. Because they can’t be recycled.
Kerala Syllabus 8th Standard Biology Notes Question 5.
Some argue that plastics are to be completely banned as they cause environmental pollution. What is your view?
Answer:
No. Without plastic, we cannot manage daily life. Control the use of plastic. avoid disposable plastic products and use thermoplastic materials.
8th Class Biology Notes Pdf Malayalam Medium Question 6.
The school science club has N decided to conduct a poster propaganda for creating awareness about pollution due to plastics. Prepare some posters for this.
Answer:
Avoid disposable plastic products use glass, ceramic utensils or natural substances
Use paper or natural materials fo decorations
Don’t dump plastic materials in soil.
8th Standard Basic Science Textbook Kerala Syllabus Question 7.
What suggestions can you propose to realise the concept of ‘plastic waste-free school’? List your findings.
Answer:
Reduce: Buy only what you need because a better way to reduce waste is by not creating it.
Reuse: Instead of throwing out plastic product you no longer think you need, try repurposing them because plastics exist for long time. Eg: use refill in ball pens, use thick plastics which can be reused, reuse the plastic bottle. The banning of plastics below the thickness of 30 micron aims at this. When thickness increases a tendency will arise to use it again.
Recycling: Is the process by which the plastics which is rendered useless is heated and subjected to certain processes to produces new materials. Recycling the rate of environmental pollution
Refuse: We can avoid the use of plastic when it is not necessary. Avoid thin plastic covers when things are bought. Use cloth bag, paper bag or thick plastic covers which can be used for long time
Fibres and Plastics Additional Questions and Answers
8th Biology Notes Malayalam Medium Kerala Syllabus Question 1.
Differentiate between thermoplastic and thermosetting plastic.
Answer:
The plastic that gets softened on heating and hardened on cooling is thermoplastic. When heating physical change occurs.
The plastic which remains soft when heated and gets hardened permanently on cooling is thermosetting plastics. Chemical change occurs when heating.
Kerala Syllabus 8th Standard Biology Notes Malayalam Medium Question 2.
Given some occasions of using plastic. Find the peculiarity of plastic used and fill the table.
Answer:
| Occasion | Peculiarity |
| As the covering of conductor | |
| To make the handles of cooking vessels | |
| To keep chemicals | |
| To make water tanks | |
| To make household materials |
Answer:
| Occasion | Peculiarity |
| As the. covering of conductor | Plastics are insulators |
| To make the handles of cooking vessels | Not conducting heat |
| To keep chemicals | Do not react with chemical |
| To make water tanks | No rusting. Less weight |
| To make household materials | Easy to use. Less weight |
Kerala Syllabus 8th Standard Chemistry Notes Malayalam Medium Question 3.
Write 4 occasions which plastic is harmful to daily life.
Answer:
- Environmental pollution when it is thrown without any control.
- When burning it cause air pollution.
- Hindrance in drainages
- The water absorption property of soil decreases when plastics are dumped in soil.
Kerala Syllabus 8th Standard Notes Question 4.
What are the uses of plastic in the field of human health?
Answer:
To produce IV tubes, bottles To produce heart valves To produce packets
Synthetic Fibres And Plastics Class 8 Notes Kerala Syllabus Question 5.
What are the uses of plastic in the field of production of house building?
Answer:
To produce roof materials, doors, plumbing and wiring materials.
Class 8 Chemistry Notes Kerala Syllabus Question 6.
List the peculiarities of plastic.
Answer:
Can mould in any shape, longlasting, insulator, do not conduct heats, not reacting with chemicals and water, will burn.
Question 7.
Separate natural and artificial polymer from the list
Rubber, wool, Pvc, Bakelite, nylon, rayon cellulose, silk, polythene, polyester
Answer:
| Natural | Artificial |
| Rubber | P.V.C |
| Wool | Polythene |
| Cellulose | Nylon |
| Silk | Rayon |
| Polyester |
Question 8.
List the merits of natural and artificial polymer
Answer:
| Merits | Demerits |
| Comfortable to wear | Less availability |
| More aeration Absorb | wrinkle easily |
| water, sweat Not | high cost not |
| easily burns | durable |
Question 9.
If we heat polyethene cover can we convert into earlier stage? Justify.
Answer:
No. Undergoes chemical change because it is thermosetting plastic.
Question 10.
Filling in the blanks.
1. Natural polymer is ……………
2. Insulin is a ………….
3. is a monomer of polythene. …………..
4. Nylon is type of plastic. …………….
5. Bakelite is an example for plastic. …………..
6. Natural polymer which has elastic nature is ……………
7. Inflammable tendency is higher in …………….
8. Thermoplastic is a ……………. type polymer.
9. The constituent unit of polymer is called
10. Polymers of plant origin are made up of …………..
Answer:
1. Starch
2. Protein
3. Ethylene
4. thermoplastic
5. thermosetting
6. Rubber
7. Synthetic fibres.
8. linear
9. monomer
10. cellulose
Question 11.
Give examples for natural fibres.
Answer:
Coconut husk, cotton, hemp, silk etc.
Question 12.
What is vulcanization? What is the use of it?
Answer:
’The process of heating rubber with sulphur is called vulcanization. By vulcanization rubber retains its form and to increase the hardness, Moreover, tensile strength, elasticity keeping stability at high temperature etc. are increased.
Question 13.
Give four difference between natural rubber and synthetic rubber.
Answer:
1. Synthetic rubber is harder than natural rubber.
2. Natural rubber is easily flammable.
3. The elasticity of natural rubber is lower than that of synthetic rubber.
4. Synthetic rubber keeps stability at higher temperature.
Question 14.
Classify the following into thermoplastic and thermosetting plastics.
Bakelite, polyvinyl chloride, nylon, celluloid, urea-formaldehyde, Teflon, polyester, polythene.
Answer:
| Thermoplastics | Thermosetting |
| Nylon | plastics |
| Polyvinyl chloride | Bakelite |
| polythene | urea formaldehyde |
| celluloid | polyester |
| Teflon |
Question 15.
Find out odd one and give reason. Bakelite, polyester, polythene, melamine formaldehyde.
Answer:
Polythene: All the others are thermosetting plastics.