NCERT Solutions for Class 8 Science Chapter 3 Synthetic Fibres and Plastics
You will find NCERT Solutions for Class 8 Science Chapter 3 Synthetic Fibres and Plastics that are helpful resources that can help you not only cover the entire syllabus but also provide in depth analysis of the topics. It will make entire memorizing process effortless and entertaining. These Chapter 3 Class 8 Science NCERT Solutions can be used to enrich knowledge and make lessons for learners more exciting.
These Class 8 NCERT Solutions are curated by the experts in a comprehensive which can be helpful in clearing your doubts instantly. Chapter 3 Synthetic Fibres and Plastics NCERT Questions and Answers are prepared as per the accordance of latest CBSE guidelines so you can score maximum marks. It is very challenging to score good marks in tests that is why we have prepared NCERT Solutions.
NCERT Solutions for Class 8 Science Chapter 3 Synthetic Fibres and Plastics
Synthetic Fibres and Plastics NCERT Solutions will useful in getting a solid understanding of the various concepts embedded in the chapter. Students should also refer previous year questions and practise test papers and worksheets to assess their key areas. Through these Class 8 Science NCERT questions and answers, students should not waste time and adopt a strategy that helps them operate and learn at maximum efficiency.
| Study Material for Class 8 Science Chapter 3 Synthetic Fibres and Plastics |
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Page No: 41
Exercise
1. Explain why some fibres are called synthetic.
Answer
Some fibres are called synthetic fibres because they are man-made. These fibres made by the combination of different types of chemicals in industries and their nature are also different in respect of natural fibre
2. Mark the correct answer.
Rayon is different from synthetic fibres because(a) it has a silk-like appearance.
(b) it is obtained from wood pulp.
(c) its fibres can also be woven like those of natural fibres..
► (b) it is obtained from wood pulp.
3. Fill in the blanks with appropriate words.
(a) Synthetic fibres are also called ________or _________fibres.
(b) Synthetic fibres are synthesised from raw materials called ________.
(c) Like synthetic fibres, plastic is also a _________.
Answer
(a) Synthetic fibres are also called artificial or man-made fibres.
(b) Synthetic fibres are synthesised from raw materials called petrochemicals.
(c) Like synthetic fibres, plastic is also a polymer.
4. Give examples which indicate that nylon fibres are very strong.
Answer
5. Explain why plastic containers are favoured for storing food.
Answer
Plastic containers are favoured for storing food because:
→ The plastics do not react with the food stored in them.
→ The plastics are light weight and are strong.
→ They are easy to handle and safe.
→ They are cheap and ductile.
6. Explain the difference between thermoplastic and thermosetting plastics.
Answer
Thermosetting plastic
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Thermoplastic
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| Thermosetting plastic cannot be bent easily. It may break when forced to bend. | Thermoplastic can be bent easily. |
| Thermosetting plastic cannot be softened by heating. Thus, it cannot be reshaped once moulded. | Thermoplastic can be softened easily by heating. Thus, it can be reshaped. |
7. Explain why the following are made of thermosetting plastics.
(a) Saucepan handles
(b) Electric plugs/switches/plug boards
Answer
(a) The handles of saucepans are made of thermosetting plastics because it is a bad conductor of heat and so, do not get heated up while cooking. So it is easier to handle the utensil while cooking. Moreover it does not get softened due to heat.
(b) Electrical plugs, switches and plug-boards are made up of thermosetting plastics because it is a bad conductor of electricity. It does not allow the electric current to pass through it, thus safe in using in electric appliances.
8. Categorize the materials of the following products into 'can be recycled' and 'cannot be recycled'.
Telephone instruments, plastic toys, cooker handles, carry bags, ball point pens, plastic bowls, plastic covering on electrical wires, plastic chairs, electrical switches.
Answer
Cannot be recycled
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Can be recycled
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Telephone instruments
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Plastic toys
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Cooker handles
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Plastic chairs
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Electrical switches
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Carry bags
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Plastic
covering on electrical wires
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Ball point pens
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Plastic bowls
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9. Rana wants to buy shirts for summer. Should he buy cotton shirts or shirts made from synthetic material? Advise Rana, giving your reason.
Answer
Rana should buy shirts made from cotton. This is because cotton is a good absorber of water. It can soak the sweat coming out of our body and expose it to the environment. Thus, it helps in evaporating the liquid (sweat), thereby cooling our body.
10. Give examples to show that plastics are non-corrosive in nature.
Answer
Plastics are noncorrosive in nature because it is a nonreactive substance. It does not react with air, water, minerals and other chemicals. So in present days most of the containers, utensils and laboratory equipments are made with plastics to store food, chemicals etc.
11. Should the handle and bristles of a tooth brush be made of the same material? Explain your answer.
Answer
No. The handle and bristles of a tooth brush should be made of different materials. The handle of a toothbrush should be hard and strong, while the bristles should be soft and flexible.
12. 'Avoid plastics as far as possible'. Comment on this advice.
Answer
Plastics are non-biodegradable materials. They take several years to decompose. It is not environment friendly and causes environment pollution. Also burning process of plastics is quite slow. In the process of burning it releases lots of poisonous gas into the atmosphere causing air pollution. Some plastics can’t be recycled and so, it is very difficult to finally dispose off such materials. Polythene bags, carelessly thrown in an eating garbage can cause death for the animals like – cows, dogs etc or sometimes even become a cause for clogging of the drains.
Page No: 42
13. Match the terms of column A correctly with the phrases given in column B.
A
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B
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| (i) | Polyester | (a) | Prepared by using wood pulp |
| (ii) | Teflon | (b) | Used for making parachutes and stockings |
| (iii) | Rayon | (c) | Used to make non-stick cookware |
| (iv) | Nylon | (d) | Fabrics do not wrinkle easily |
Answer
A
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B
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| (i) | Polyester | (d) | Fabrics do not wrinkle easily |
| (ii) | Teflon | (c) | Used to make non-stick cookware |
| (iii) | Rayon | (a) | Prepared by using wood pulp |
| (iv) | Nylon | (b) | Used for making parachutes and stockings |
14. 'Manufacturing synthetic fibres is actually helping conservation of forests'. Comment.
Answer
The natural fibers are obtained from plants and animals, whereas the synthetic fibers are obtained by chemical processing of petrochemicals. Unlike natural fibers, manufacturing of synthetic fibers do not require to cut trees or hunting of any animal. In this way manufacturing synthetic fibers is actually helping conservation forests.
15. Describe an activity to show that thermoplastic is a poor conductor of electricity.
Answer
We will design a circuit to see that thermoplastics are poor conductors of electricity. We need a bulb, some wires, a battery, a piece of metal, and a plastic pipe. Set up the circuit first with the metal and then with the plastic pipe (as shown in the figure). After you switch on the current, you will observe that the bulb glows in the former case. In the latter case, the bulb does not glow. Hence, a plastic pipe (which is a thermoplastic) is shown to be a poor conductor of electricity.
Answer
We will design a circuit to see that thermoplastics are poor conductors of electricity. We need a bulb, some wires, a battery, a piece of metal, and a plastic pipe. Set up the circuit first with the metal and then with the plastic pipe (as shown in the figure). After you switch on the current, you will observe that the bulb glows in the former case. In the latter case, the bulb does not glow. Hence, a plastic pipe (which is a thermoplastic) is shown to be a poor conductor of electricity.
Go Back To NCERT Solutions for Class 8 Science
Chapter 3 Synthetic Fibres and Plastics NCERT Solutions for Class 8 Science
Class 8 Science NCERT Solutions will be useful in gaining good marks in the examinations. It will be useful in building a great foundation of concepts and make easy for the students to understand basics. NCERT Solutions prepared by our experts try to provide all round clarity of questions. These are very much essential in steering students towards their goal.
Class 8 Science Chapter 3 Synthetic Fibres and Plastics NCERT Questions and Answers - Topics
• What are Synthetic Fibres?
• Types of Synthetic Fibres
→ Rayon
→ Nylon
→ Polyester and Acrylic
• Characteristics of Synthetic Fibres
• Plastics
• Plastics as Materials of Choice
→ Plastic is Non-reactive
→ Plastic is Light, Strong and Durable
→ Plastics are Poor Conductors
• Plastics and the Environment
Chapter 3 Synthetic Fibres and Plastics NCERT Solutions for Class 8 Science - Notes
• Fabrics are made from fibres obtained from natural or artificial source.
• Jute, cotton, wool and silk are natural fibres, they are obtained from plants or animals. Nylon, rayon like fibres are synthetic or man-made fibres.
• A polymer is an aggregated structure consisting of numerous small simple molecules of one or more kind, called monomers.
• Types of Synthetic Fibres:
→ Rayon or Artificial silk: It is made from pure cotton or wood pulp. The fibres of rayon are long, smooth and shiny. It is a good conductor of heat and cool to wear.
→ Nylon: Nylon is a fully synthetic polymer developed simultaneously in New York and London. It was prepared from coal, water and air. Its fibres resemble the silk fibre.
→ Polyesters: Terrylene and Acrylic are synthetic fibres called polyesters. The fibres of polyester are long and smooth. These fibres do not absorb stains and easily wash.
→ Acrylic: These are the synthetic fibres which resemble to natural wool. They are durable and affordable.
• Advantages of Synthetic Fibres: They dry up quickly, and are durable, less expensive, readily available, easy to maintain and synthetic fibres melt on heating.
• Disadvantages of Synthetic Fibres: If synthetic fibre clothes catch fire, they can melt and stick to the body of the person wearing it.
• Plastics: It is also a polymer like the synthetic fibre. All plastics do not have the same type of arrangement of units. Some plastic polymers have linear arrangement of units, whereas in others it is cross-linked arrangement.
• Plastic is easily mouldable, recycled, reused, coloured, melted, rolled into sheets or made into wires.
• Polythene (poly + ethene) is a plastic which is used for making commonly used polythene bags.
• Thermoplastics: Plastics which get deformed easily on heating and can be bent easily are known as Thermoplastics. Polythene and PVC are the examples. These are used for manufacturing toys, combs and various types of containers.
• Thermosetting Plastics: Plastics which when moulded once, cannot be softened by heating are called Thermosetting plastics. Bakelite and Melamine are the examples.
• Plastics as Materials of Choice
→ Plastics are non-reactive. They do not react with water, air and do not corrode easily. So, they are used to store various materials, including many chemicals.
→ Plastics are light, strong and durable. They are generally cheaper than metal. So, they are widely used in industry and household articles.
→ Plastics are poor conductors of heat and electricity.
• A material which gets decomposed through natural processes, such as action by bacteria, is called biodegradable.
• A material which is not easily decomposed by natural processes is termed non-biodegradable.
• Since plastic takes several years to decompose, it is not environment friendly.
• How can we reduce abuse of plastics?
→ Avoid the use of plastics as far as possible.
→ Recycle plastic waste, especially thermoplastics which can be recycled.
→ The best way is to follow 4R principle, namely, Reduce, Reuse, Recycle and Recover.
Chapter 3 Synthetic Fibres and Plastics Class 8 Science Questions and Answers - MCQ Questions with answers
1. Rayon blended in wool will result in
a) Shirt
b) Bedsheets
c) Table cover
d) Carpets
► d) Carpets
2. What is the saturated solid state?
a) A state at which solid can change into liquid at constant pressure and temperature
b) A state at which solid can change into liquid at constant temperature but change in pressure
c) A state at which solid can change into liquid at constant pressure but changing temperature
d) None of the above
► c) a state at which solid can change into liquid at constant pressure but changing temperature
3. Electrical wires have a coating of insulating material. The material generally used for insulation is:
a) Sulphur
b) Graphite
c) PVC
d) All of the above
► c) PVC
4. Remoulding can be done of:
a) Polyvinyl chloride
b) Bakelite
c) Melamine
d) Formaldehyde
► a) Polyvinyl chloride
5. In electrical field, PVC is used to make
a) pipes
b) wire cover
c) tungsten wire
d) switches
► a) pipes
6. Which of the following fibres are made from petroleum products?
a) acrylic
b) decron
c) acrylon
d) all of the above
► d) all of the above
7. The plastic that is used in making uniforms of firemen is
a) teflon
b) melamine
c) bakelite
d) polythene
► b) melamine
8. Yarn is twisted to form:
a) thread
b) fabric
c) plastic
d) fibre
► a) thread
9. First man-made fibre produced chemically is:
a) Nylon
b) Polyester
c) Terylene
d) Rayon
► a) Nylon
10. Which of the following items cannot be recycled?
a) Plastic milk bottles
b) Plastic food trays
c) CD/DVD cases
d) Plastic cups
► c) CD/DVD cases
These Chapter 3 Class 8 Science NCERT Solutions are curated by the experts in a comprehensive which can be helpful in clearing your doubts instantly. It will let you explore answers of those questions which you're finding difficult to solve. You can pinpoint your weaknesses and prepare accordingly to change it in a positive way.