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

1. Explain why some fibres are called synthetic. 

Ans: Some fibres are called synthetic because- 

• They are man-made, meaning they are made from chemicals like petrochemicals. 

• They are artificial fibres made with or without using any natural raw material from plants or animals. 

• Synthetic fibres are typically a chain of small units joined together to form a large single unit called a polymer.

• Examples of synthetic fibres are nylon, rayon, acrylic, and polyester.

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. 

Ans: (b) it is obtained from wood pulp

Rayon is obtained from a natural source, wood pulp; while most synthetic fibres are made without using any natural raw material from plants or animals.

3. Fill in the blanks with appropriate words. 

(a) Synthetic fibres are also called __________ or __________ fibres. 

Ans: artificial or man-made

(b) Synthetic fibres are synthesized from raw material called __________ 

Ans: petrochemicals

(c) Like synthetic fibres, plastic is also a __________ . 

Ans: polymer

4. Give examples which indicate that nylon fibres are very strong. 

Ans: Nylon is a man-made fibre produced from coal water and air. It is strong, elastic, and light. It is said to be stronger than steel wire. Because of this property nylon is used for making parachutes and ropes for rock climbing. It is also used in seat belts for cars and fishing nets as well.

5. Explain why plastic containers are favored for storing food. 

Ans: Plastic containers are most convenient for storing food because:

• of their lightweight, good strength, lower price, and easy handling. 

• Most importantly plastic containers do not react with the food item that is stored in them, making them safe to store.

6. Explain the difference between thermoplastic and thermosetting plastics. 

Ans: The difference between thermoplastic and thermosetting plastics is given below,

7. Explain why the following are made of thermosetting plastics. 

(a) Saucepan handles 

(b) Electric plugs/switches/plug boards 

Ans: 

(a) Saucepan handles – Thermosetting plastics, such as melamine, are used because they resist fire and can withstand heat better than other polymers. They also don't easily bend or melt when heated.

(b) Electric plugs/switches/plug boards – They are made from thermosetting plastics like bakelite because it is a poor conductor of heat and electricity. Thus in case of any short or current leakage, it will not allow the electricity to pass and harm the user.

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. 

Ans:

A. Can be recycled: 

• Plastic toys

• Carry bags

• Ball point pens

• Plastic bowls

• Plastic covering on electrical wires

• Plastic chairs

• Electrical switches 

B. Cannot be recycled: 

• Telephone instruments

• Cooker handles

• Electrical switches. 

9. Rana wants to buy shirts for summer. Should he buy cotton shirts or shirts made from synthetic material? Advise Rana, giving your reason. 

Ans: Rana should buy cotton shirts for summer because cotton can absorb the sweat easily and allows the evaporation of sweat through its pores, helping Rana to cool down his body during the hot summer season. Also, it is not advised to buy synthetic shirts because the synthetic fibres do not absorb sweat and make it uncomfortable during the hot climate.

10. Give examples to show that plastics are non corrosive in nature. 

Ans: Plastics are non corrosive in nature because- 

• They do not react with water and air. That is why an exposed iron nail rusts, but plastic remains unaffected.

• Plastics do not react even with most chemicals. For example, cleaning materials like acid and detergents are usually stored in plastic containers but not in metal containers.

• Plastic is used to store food as well because it does not react with the food stored in it. For example, we store pickles, dry food in plastic containers but not in metal containers.

11. Should the handle and bristles of a toothbrush be made of the same material? Explain your answer. 

Ans: No, the handle and bristles of a tooth brush should not be made of the same material because the bristles which are used to brush our teeth must be soft and flexible; while the handle which we hold and grip on must be hard and strong.

That is why the bristles are made up of nylon, while the handle is made of thermosetting plastics like melamine or bakelite.

12. ‘Avoid plastics as far as possible’. Comment on this advice. 

Ans: ‘Avoid plastics as far as possible’ as-

• Plastics are non-biodegradable in nature, meaning it is not easily decomposed by natural processes. Plastics typically take several years to decompose and are not environmentally friendly. They tend to cause environmental pollution as well. 

• Even when the plastics are burnt to get rid of them, they do not burn completely and would release poisonous fumes into the atmosphere causing air pollution.

• The plastic bags which are thrown in dumps are eaten and swallowed by animals like cows, which would choke the respiratory tracts of the animal, resulting in its death.

• There are also cases of plastic bags clogging our drainage systems.

• Hence we should avoid them as much as possible and try to use plastic alternatives like cotton or jute bags.

• As responsible citizens, we must be environmentally friendly and practice Reduce, Reuse and Recycle principles.

13. Match the terms of column A correctly with the phrases given in column B. 

Ans: 

(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.

Ans: It is true that manufacturing synthetic fibres is actually helping conservation of forests. As synthetic fibres are man-made, meaning they are made from chemicals like petrochemicals. Synthetic fibres are artificial fibres that can be made with or without using any natural raw material from plants or animals. Thus their existence has helped in the substitution of natural fibres like cotton, silk, wool, jute which are obtained from plants and animals. So it means that trees need not be cut down for their production, since there is a man-made alternative. This can aid in preventing deforestation as well.

15. Describe an activity to show that thermoplastic is a poor conductor of electricity.

Ans: In order to show that thermoplastic is a poor conductor of electricity, let us make use of a simple circuit with a bulb, battery, switch, metal rod, and PVC (thermoplastic) of the same dimensions, and connecting wires.

• Set up two circuits as shown below.

• Switch on the circuit.

• It is observed that in the first case (i), with a metal rod, the bulb lights up. It implies that the metal rod is a good conductor of electricity.

• In the second case (ii), with a PVC pipe, the bulb does not light up. It implies that the PVC i.e. thermoplastic is a poor conductor of electricity.

NCERT Solutions for Class 8 Science Chapter 3 - Synthetic Fibres and Plastics

NCERT Solutions for Class 8 Science Chapter 3 – Free PDF Download

NCERT Solutions for Class 8 Science Chapter 3 are very crucial from the final exam’s perspective. The NCERT Solutions for Class 8 Science Chapter 3 Synthetic Fibres and Plastics are provided in such a way that students get a better understanding of the topic. Clarity of concept, quick absorption of the content, and an easy language to comprehend are some of the main objectives of this solution. NCERT Solutions of Class 8 Science Chapter 3 learning is especially important to understand the NCERT concepts, terminologies, and questioning patterns.

The solutions are specially drafted, topic-wise, by specialized professional staff with a greater understanding of the concepts, and the kind of answers that need to be written in exams. Downloading these NCERT Class 8 Chapter 3 Science Solutions PDF will undoubtedly help you in learning and crystal-clear logical thinking.

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NCERT Solutions for Class 8 Science Chapter 3 - Synthetic Fibres And Plastics

Class 8 Chapter 3 Synthetic Fibres and Plastics includes different topics like synthetic fibres meaning, types of synthetic fibres, their characteristics, plastics, benefits of plastics, use of plastic as a choice, hazards of plastic on the environment, and exposure to many fibres like nylon, rayon, melamine, bakelite, etc.

This chapter deals with the type of cloth we use in our daily life. The cloth is made up of fabric, so there are two types of fabric explained in the chapter. The natural fibre which is obtained from plants and the synthetic fibre which is synthesized by humans using some chemicals.

There are a variety of synthetic fibres present in the environment with a diverse range of characteristics and benefits. This Class 8th Science Chapter 3 explains the various things around us made up of different kinds of synthetic fibres.

We have to understand the core concepts of these fibres to understand their implementation in their surroundings. Also, there is an elaborate description of plastics, the types of plastics, the impact of plastic on the environment, and a logical understanding among humans to make an easy choice whether to use plastic or not. Here also, the implementation of plastics is essential in various things surrounding us, and the questions are asked about these objects and their texture with justified reasons.

Key Points discussed In NCERT Class 8 Science Chapter 3 

• Synthetic fibres and plastics, like natural fibres, are made up of polymers, which are very massive units. Polymers are made up of many small units.

• Synthetic fibres are made through chemical processes, whereas natural fibres come from plants and animals. These fibres, like natural fibres, may be woven into garments.

• Synthetic fibres have a wide range of applications, including ropes, buckets, furniture, containers, and other everyday items, as well as highly specialized applications in airplanes, ships, spacecraft, and healthcare.

• Rayon, Nylon, Polyester, and Acrylic are the names given to synthetic fibres based on the chemicals used to make them.

• The strength, water absorption capacity, burning nature, cost, and durability of different types of fibres differ from one another.

• Today, life would be unimaginable without plastics. Plastic is present everywhere, including the house and the outdoors.

• The ecology suffers as a result of plastic waste. Plastics emit harmful fumes when they are burned. They might take years to decompose if dumped in the ground. This is due to the fact that they are non-biodegradable.

• We must use synthetic fibres and plastics in such a way that we may benefit from them while also reducing the environmental risks to living communities caused by them.

Benefits of NCERT Solutions for Class 8 Science

• All in text, exemplar, and exercise questions are not only answered in Vedantu's pdf but also explained with every reason for a better understanding and reliability of students. This offline mode of study through PDF will help you to maintain notes in a sequential manner too, which is crucial for merit marks in exams, so download these pdfs for free right now. 

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What makes Vedantu's Ncert Solutions For Class 8 Science Chapter 3 Synthetic Fibres And Plastics very crucial in this Chapter 3 is the application of these concepts. The question is not asked directly about the topics discussed above and their definitions instead mostly about their applications in daily life so unless we learn the concept we can't apply them. Here, Vedantu brings plenty of questions regarding application in everyday life too.

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The study material is designed according to the mental ability of class-wise children, various quizzes are present, frequent mock tests for revision, interlinking of concepts in topics, and query options for any doubt of students.

Chapter wise NCERT Solutions for Class 8 Science

• Chapter 1 - Crop Production and Management

• Chapter 2 - Microorganisms : Friend and Foe

• Chapter 4 - Materials : Metals and Non-Metals

• Chapter 5 - Coal and Petroleum

• Chapter 6 - Combustion and Flame

• Chapter 7 - Conservation of Plants and Animals

• Chapter 8 - Cell - Structure and Functions

• Chapter 9 - Reproduction in Animals

• Chapter 10 - Reaching The Age of Adolescence

• Chapter 11 - Force and Pressure

• Chapter 12 - Friction

• Chapter 13 - Sound

• Chapter 14 - Chemical Effects of Electric Current

• Chapter 15 - Some Natural Phenomena

• Chapter 16 - Light

• Chapter 17 - Stars and The Solar System

• Chapter 18 - Pollution of Air and Water

Along with this, students can also view additional study materials provided by Vedantu, for Class 8 :

• NCERT Exemplar for class 8 Science Chapter 3

• CBSE Revision Notes for class 8 Science Chapter 3