RBSE Solutions for Class 8 Science Chapter 3 Synthetic Fibres and Plastics

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RBSE Solutions for Class 8 Science Chapter 3 Synthetic Fibres and Plastics are part of RBSE Solutions for Class 8 Science. Here we have given RBSE Rajasthan Board Solutions for Class 8 Science Chapter 3 Synthetic Fibres and Plastics.

Rajasthan Board Solutions for Class 8 Science Chapter 3 Synthetic Fibres and Plastics

Board RBSE
Class Class 8
Subject Science
Chapter Chapter 3
Chapter Name Synthetic Fibres and Plastics
Number of Questions Solved 43
Category RBSE Solutions

Synthetic Fibres and Plastics Textbook Questions Solved

I. Multiple Choice Questions
Question 1.

  1. The material used for making non stick utensils of kitchen is:
    (a) PVC
    (b) Polyether
    (c) Teflon
    (d) Rayon
  2. Which of the following group is of synthetic fibres?
    (a) Nylon, Terelene, Rayon
    (b) Compound
    (c) Acrylic, Silk, Wool
    (d) PVC, Polyether, Bakelite
  3. The handles of utensils are made from-
    (a) Polyether
    (b) Nylon
    (c) PVC
    (d) Bakelite
  4. Which is not the property of plastics ?
    (a) Inert
    (b) Durable
    (c) Light weight
    (d) Conduction of electricity
  5. Thermoplastics is
    (a) Bakelite
    (b) Melamine
    (c) Polyether
    (d) None of these

Answers:

  1. (c)
  2. (a)
  3. (d)
  4. (d)

Question 2.
Fill in the blanks:

  1. Synthetic fibres are also called………………or fibres.
  2. Rayon is also called……………..
  3. The polymerisation of acetonitryl gives……………..
  4. Plastic is also a type of……………..

Answers:

  1. artificial, polymer
  2. artificial silk
  3. Orion
  4. synthesised polymer

Question 3.
Match the column A with column B

Column A Column B
Rayon (a) Non stick coating
Nylon (b) Artificial fibre
Thremosetting plastic (c) Pipes
PVC (d) Clothes

Answer:

Column A Column B
Rayon (b) Artificial fibre
Nylon (d) Clothes
Thremosetting plastic (a) Non stick coating
PVC (c) Pipes

Synthetic Fibres and Plastics Short Answer Type Questions

Question 1.
Why it is not advice to burn plastics and synthetic fibres?
Answer:
It is not advice to burn plastics and synthetic fibres because when it is burnt it requires a great amount of energy and during this process poisonous gases are released in such a great amount which makes the environment polluted.

Question 2.
What are thermoplastics? Explain with example.
Answer:
Such plastics which get deformed easily on heating are thermoplastics. A Thermoplastic is a polymer that turns liquid when heated and freezes to very glassy state when cooled sufficiently. They can be recycled. Some examples of thermoplastics are polythene and PVC (polyvinyl chloride).

Question 3.
Terrycot is obtained by mixing two types of fibres? Name these fibres.
Answer:
Terrycot is a mixture of terelyne and cotton. .

Question 4.
What is non-biodegradable substances?
Answer:
The materials which do not get decomposed by various natural processes or take too long to decompose, are called non-biodegradable materials. All kinds of plastics, artificial fibres and metal cans used for packaging food and soft drinks are non- biodegradable materials.

Question 5.
What is polymerisation?
Answer:
The process of forming a polymer by the interlinking of monomer is called polymerisation.

Synthetic Fibres and Plastics Long Answer Type Questions

Question 1.
Write the uses of synthetic fibres in daily life?
Answer:
Synthetic fibres are man made fibre. Following are the uses of some main synthetic fibres.

  1. Nylon: It is used to make stocking, seat belts, ropes, tents, toothbrushes, sleeping bags, curtains and parachutes etc.
  2. Rayon: It is used as dress material mixed with cotton. It is used to make curtains, bedsheets etc. It is mixed with wool to make beautiful carpets.
  3. Polyester: PET is also derived from polyester which in terms is used to make containers, utensils, feeling wires etc.
  4. Acrylic: It is used to make sweaters and suit length. It is cheaper than natural wool.

Question 2.
Explain the statement “do not use plastics in daily life as far as possible”.
Answer:
Extensive use of synthetic polymers has led to certain environmental hazards, making with a matter of global concern, plastic proved to be a magical material for the world because of its properties, but it has a negative side also.
They are:

  1. Plastic cause health hazards and are very harmful to the environment, as they are non-biodegradable and cannot be decomposed by micro-organisms.
  2. Hence they prevent rain water from seeping into the earth and affect plant growth.
  3. Plastics lying on roadsides and floating in lakes and streams provide shelter for germs and animals causing diseases.
  4. Toxic to aquatic life when placed in water.
  5. Produce toxic gases when burnt, hence causing air pollution.
  6. Take several years to decompose.
    To avoid these problems we should prevent-
  7. By recycling which involved collecting, sorting and processing the plastic.
  8. Follow 4R principal – reduce, reuse, recycle and recover.
  9. Making use of cotton jute bags while shopping.
  10. By dividing the garbage into biodegradable and non-biodegradable wastes and hence recycling the non-biodegradable wastes.

Question 3.
How synthetic fibre nylon is formed? Write its different properties.
Answer:
Nylon is prepared by mixing of adipic acid and hexamethylene diamine. It is completely a synthetic fibre.

  1. Nylon fibre is a strong plastic and light.
  2. It is lustrous and easy to wash.
  3. Clothes made from nylon does not get wrinkle and stable for long time.
  4. This is durable.
  5. They soak less water and dry up easily.
  6. Clothes of nylon does not have threat of clothes worn.
  7. They do not need extra care.

Synthetic Fibres and Plastics Additional Questions Solved

I. Multiple Choice Questions
Question 1 .
The fibre obtained by processing cellulose is called
(a) Rayon
(b) Nylon
(c) Polystyrene
(d) Terylene

Question 2.
This is the synthetic fibre
(a) Wool
(b) Acrylic
(c) Cotton
(d) Polystyrene.

Question 3.
The fibre obtained by the chemical
treatment of wood pulp is called:
(a) Rayon
(b) Silk
(c) Cotton
(d) Polyester

Question 4.
Acrylic, a man made fibre is a good substitute of a natural fibre. Which is this natural fibre?
(a) Wool
(a) Silk
(c) Cotton
(d) Jute

Question 5.
Polyester is a polymer of
(a) Ester
(a) Ethane
(c) Ethylene
(d) Methane

Question 6.
The smallest unit of polymer is called
(a) Cell
(b) Atom
(c) Monomer
(d) Plastic

Question 7.
The thermosetting plastic is
(a) PVC
(b) Bakelite
(c) Teflon
(d) Nylon

Question 8.
Which of the following is not a thermoplastic?
(a) PVC
(b) Polythene
(c) Melamine
(d) Teflon

Question 9.
Which of the following plastics cannot be remoulded?
(a) PVC
(b) Polythene
(c) Bakelite
(d) Teflon

Question 10.
These are generally the bad conductor of heat-
(a) Natural fibre
(b) Synthetic fibres
(c) Cranes
(d) Plastics

Question 11.
A synthetic fibre obtained from petroleum is:
(a) Bakelite
(b) Rayon
(c) Melamine
(d) Polyester

Question 12.
Which of the following is not biodegradable?
(a) Cotton
(b) Wool
(c) Nylon
(d) Paper

Question 13.
Which of the following can be recycled?
(a) Plastic bowls
(b) Electrical switches
(c Telephone instruments
(d) Ballpoint pens

Question 14.
Which material is best suited for
covering electric wires?
(a) Polyester
(b) Polythene
(e) PVC
(d) PET

Question 15.
PET is a
(a) Polyamids
(b) Polyester
(e) Nylon
(d) Rayon

Answers:

1. (a)
2. (b)
3. (a)
4. (a)
5. (a)
6. (e)
7. (b
8. (c)
10. (d)
11. (c)
12. (c)
13. (a)
14. (c)
15. (b)

Synthetic Fibres and Plastics Very Short Answer Type Questions

Question 1.
What are natural fibres?
Answer:
Natural fibres are obtained from natural sources like plants or animals.

Question 2.
What are synthetic fibres?
Answer:
The fibres which are man-made and are prepared from chemicals in the laboratory.

Question 3.
Define plastic.
Answer:
Plastic is a polymer which is easily moulded or set into any desired shape when heated. It hardens on cooling to make a durable object.

Question 4.
How many types of plastics are found?
Answer:
Plastics are of two types
(a) Thermoplastics
(b) Thermosetting plastics.

Question 5.
What are polymers?
Answer:
The synthetic fibres made from small units which combines to form long chain are called polymers.

Question 6.
How orlon is obtained?
Answer:
Orion is obtained by the polymerisation of acetonitrile. It resembles with woollen fibres.

Synthetic Fibres and Plastics Solutions Short Answer Type Questions

Question 1.
Illustrate that nylon thread is stronger than cotton, wool and steel.
Answer:
Take an iron stand with the clamp. Take a cotton thread of about 60 cm length. Tie it to the clamp so that it hangs freely from it as at the free end, suspend a pen so that weight can be placed in it. Add weight one by one till the thread breaks. Note down the total weight required to break the thread. This weight indicates the strength of the thread. Repeat the same activity with threads of wool and steel of similar length and thickness. You will observe that nylon thread is strongest among them.

Question 2.
Why is polyester quite suitable for making dress material?
Answer:
Polyester is synthetic fibre. Fabric made from polyester does not get wrinkled easily. It remains crisp and is easy to wash, so it is quite suitable for making dress materials. Terylene is a type of popular polyester. It can be drawn into very fine fibres that can be woven like any other yam. PET is also popular polyester. It is used for making bottles, utensils, tiles, wires and many other useful products.

Question 3.
Rayon is not considered as a synthetic fibre completely. Justify the statement.
Answer:
In the true sense or literally rayon is not considered as a synthetic fibre completely because, it involves the regeneration of cellulose from naturkl resources, in the synthesis, to improve the quality of fibre. Hence it is also called as modified natural fibre.

Question 4.
Write some properties and use of melamine.
Answer:
Melamine is versatile material. It resists fire and can tolerate heat better than other plastics. It is used for making floor tiles, kitchenware and fabrics which resists fire.

Question 5.
Is terylene a type of polyester? Explain.
Answer:
Polyester is light weight and strong. Terylene, as it is very elastic, used in making conveyor belt. Polyester under the name ‘mylar’ is used in making recording tapes in audio, video cassettes and floppy discs. Activity and questions based on it.

Question 6.
Clothes of nylon, polyester, terylene and cotton fibre are soaked in water and then dried up on rope. What do you observe?
Answer:
We observe that nylon, polyester, terylene clothes dry up quickly than cotton clothes. Synthetic threads soak less water hence dry easily.

Question 7.
Clothes made of different fibres are pressed turn-by-turn by your fist. What do you observe?
Answer:
Cotton gets wrinkled but nylon, polyester and rayon does not get wrinkled.

Question 8.
Threads made of different fibres are stretched. What do you sobserve?
Answer:
We observe that it is difficult to stretch nylon, polyester, rayon thread than cotton thread. They are more strong. Therefore, we can say that synthetic fibres are strong and durable for long time.

Question 9.
You are daily going to school wearing uniform. Have you ever thought how this uniform is made?
Answer:
The uniform is made from clothes, clothes are made from fibres. From where do these fibres come from? Some fibres are obtained from nature called natural fibres and some are made by human being called synthetic fibres. Let’s get the knowledge about the things used in our daily life made from natural fibre or synthetic fibre. The name of fibres used for making articles are given in table:

Articles Type of fibre
Parachute
Brush
Curtains
Sweater

Answer:

Articles Type of fibre
Parachute Synthetic fibre (Nylon)
Brush Synthetic fibre (Nylon)
Curtains Synthetic fibre (Nylon)
Sweater  Synthetic fibre (Nylon)

Question 10.
With the help of an activity show the properties of two types of plastic.
Answer:
Activity:
Put some hot water in a plastic bucket and try to press it. You will feel that the bucket has become comparatively soft. Now at the time of cooking try to press the handle of the pressure cooker. You observe that handle neither becomes hot nor soft, that is both the bucket and handle made of plastics show different properties. This is because the internal structures of both are different. Thus plastics are of two types:
(a) Thermoplastic (thermally soft) i.e. it becomes soft on heating.
(b) Thermosetting plastic (thermally strong) i.e. it remains hard and retains its property even on heating.

Synthetic Fibres and Plastics Long Answer Type Questions

Question 1.
How rayon or artificial silk is produced? Write its uses?
Answer:
We know that silk was discovered in China and was kept a closely guarded secret for a long time. Fabric made from the silk were very costly. However, the beautiful texture of silk fascinated everybody attempts where made by the chemists to make artificial silk, and they were successful by the end of the nineteenth century. The product they developed is called rayon and has similar properties to the silk. The raw material for the production of rayon is pure cotton or wood cellulose. Rayon is sometimes called regenerated fibre, because it is produced by modifying the natural fibre. Rayon is not truly an artificial fibre because its raw material is a natural fibre. However for all practical purposes it is included in to man – made fibre or synthetic fibre.
Uses of Rayon:
The filament of rayon can be woven like any other natural fibre. They have a feel and texture of natural silk.

  1. Rayon filament are blended with wool in the manufacture of carpet
  2. Rayon filaments are blended with cotton to make smooth silk cloth which can be used for making bed sheets.
  3. Long filaments of rayon are used for making reinforced automobile tyres.

Question 2.
Define polyester. Write its properties and uses.
Answer:
Polyester is a synthetic fibre made from petroleum product which contain a large number of esters. It has the property of repelling water, known as hydrophobia. Blended fibres are more comfortable than synthetic fibres and are easier to maintain
than natural fibre. Properties of polyester:

  • It is a very strong fibre. Polyester clothes are quite durable.
  • Polyester clothes are easy to maintain their wrinkle free and resist wear and tear.
  • Polyester is light in weight and elastic.

Uses of polyester:

  • It is a popular fibre for making shirt, trouser, saree and other dress material.
  • It is used to make sail of sailing boat as it is least.
  • Hollow polyester fibre trap heat. Hence, they are used to ma^e jacket, sleeping bags, etc.
  • In industry polyester is used to make bottle, jar, utensils, wire, films and many other useful product.

Question 3.
Explain the advantages of fibres and plastic?
Answer:
Both fibre and plastic have dominated the world since quite sometime due to their user-friendly characteristics.
Plastic has substituted natural product, due to much of its good qualities.

  1. Plastic is light in weight. It is easy to carry, can be managed well and is easy to handle. Being lighter as compared to metals, plastics are used in cars, aircraft and spacecraft too.
  2. Plastic is non-reactive you cannot keep pickle or anything sour in metal container as metals react with acid. Again metal like iron get rusted when left exposed to moisture and air. But plastics do not react with water or air. That is why they are used to store various kind of food material and also many chemicals.
  3. Plastic is strong and durable. That is why it is used to make buckets, tubs and most of our household articles.
  4. Plastic can be moulded into different shape and size. Hence, it is used for various purposes from insulating wire to making spacecraft.
  5. Plastic is low in price. This is why it is within the reach of common man.

Question 4.
Explain the uses of thermoplastic and thermosetting plastic.
Answer:

  1. Thermoplastic: As these plastic are soften on heating, they can be recycled, reused, coloured, melted and moulded into different shape.
    Some thermoplastic and their uses are mentioned below:
    (a) FVC: one of the most commonly used plastic is PVC (polyvinyl chloride). PVC is used as a building material and to make enclosure for electronic item.
    (b) Teflon: Teflon is a scratch proof, corrosion-resistant plastic, which is used to provide protective covering to materials.
    (c) Polyethylene (PE): It has a wide range of inexpensive uses that include making supermarkets bags, plastic bottle, packing material for milk, and some other liquid.
    (d) Polystyrene (PS): It is used for making disposable untensils, food container, cover for CD and cassettes.
  2. Thermosetting: Such plastic once moulded cannot be heated and recanted into another. Some thermosetting plastic are:
    (a) Bakelite: Bakelite is used for making plugs, sockets, switches and other electrical fitting.
    (b) Melamine: It is used for making unbreakable kitchenware. Melamine plastic is also coated on the uniform of firemen.

We hope the given RBSE Solutions for Class 8 Science Chapter 3 Synthetic Fibres and Plastics will help you. If you have any query regarding RBSE Rajasthan Board Solutions for Class 8 Science Chapter 3 Synthetic Fibres and Plastics, drop a comment below and we will get back to you at the earliest.