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

NCERT Solutions for Class 8 Science Chapter 3 – Synthetic Fibres and Plastics, contains solutions to various questions in Exercise for Chapter 3.  At the end of the Solutions, all the keywords and Notes which are important to understand Science Chapter 3 – Synthetic Fibres and Plastics, have been explained in a simple and easy to understand manner. We are providing NCERT Solutions for Class 8 all subjects which can be accessed by clicking here.

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

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

NCERT Solutions for Class 8 Science Chapter 3 – Synthetic Fibres and Plastics– Solutions to Question 1 to Question 4

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NCERT Solutions for Class 8 Science Chapter 3 – Synthetic Fibres and Plastics– Solutions to Question 4 to Question 7

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NCERT Solutions for Class 8 Science Chapter 3 – Synthetic Fibres and Plastics– Solutions to Question 7 to Question 9

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NCERT Solutions for Class 8 Science Chapter 3 – Synthetic Fibres and Plastics– Solutions to Question 10 to Question 13

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NCERT Solutions for Class 8 Science Chapter 3 – Synthetic Fibres and Plastics– Solutions to Question 13 to Question 15

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NCERT Solutions for Class 8 Science Chapter 3 – Synthetic Fibres and Plastics– Solutions to Question 15

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NCERT Solutions for Class 8 Science Chapter 3 – Synthetic Fibres and Plastics– Definition of the Keywords-Synthetic Fibres, Polymer, Rayon, Nylon, PET, Petrochemicals, Acrylic, Polythene, Thermoplastics, Thermosetting and Biodegradable.

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NCERT Solutions for Class 8 Science Chapter 3 – Synthetic Fibres and Plastics , Exercises includes – Fill in the blanks, Tick the correct, Match the following , MCQ’s and Questions/ Answers  which helps you to understand the topic covered in Synthetic Fibres and Plastics Class 8, in a better manner to help you to score good marks in your examinations.

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

Question 1:

Explain why some fibres are called as synthetic.

Answer 1.

The fibres which are man-made or artificial and are not naturally obtained are known as synthetic fibres. Nylon, rayon, and polyester are some examples of synthetic fibres.

Question 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

Answer 2.

(b) it is obtained from wood pulp

Question 3

Fill in the blanks with appropriate words:

(a) Synthetic fibres are also called ______ or _______ fibres.

(b) Synthetic fibres are synthesised from raw material called ________.

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

Ans 3.

(a) Synthetic fibres are also called man-made or artificial fibres.

(b) Synthetic fibres are synthesised from raw material called petrochemicals.

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




Question 4

Give examples which indicate that nylon fibres are very strong.

Answer .

(a) It is used for reinforcement in rubber material like car tires.

(b) It is used in making seat belts, tents, curtains etc.

(c) It is used as a rope in rock climbing and in parachutes.

Question 5

Explain why plastic containers are favoured for storing food.

Answer 5.

Plastic containers are favoured because of the following reasons:

  • Plastic is light-weight, easy to carry and handle, cheaper in price and more convenient than other materials.
  • It is non-reactive so does not react with the food in containers.

Question 6

Explain the difference between the thermoplastic and thermosetting plastics.

Answer 6

difference

Question 7

Explain why the following are made of thermosetting plastics.

(a) Saucepan handles

(b) Electric plugs/switches/plug boards

Answer 7

(a) Thermosetting plastics are used to make saucepan handles because they are bad conductors of heat, resist fire and do not get softened on heating like other plastics. For example- Melamine.

(b) Thermosetting plastics are used in making Electric plugs/switches/plug boards because they are poor conductors of electricity and heat. For example- Bakelite.

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

Question 8

Categorise 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 8.

Can be Recycled:

(a)Plastic chairs

(b)Plastic bowls

(c)Plastic toys

(d)Plastic covering on electrical wires

(e)Carry bags

(f)Ballpoint pens

Cannot be Recycled

(a) Cooker handles

(b) Electrical switches

(c) Telephone




Question 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 9.

Rana is advised to purchase a cotton shirt in summer because cotton is a good absorber of sweat and has pores which facilitate easy evaporation of sweat allowing the person to feel cool in summer. On the other hand, synthetic materials do not absorb sweat and therefore are very uncomfortable for wearing in summers.

Question 10

Give examples to show that plastics are noncorrosive in nature.

Ans10.

Plastics are non-corrosive in nature because:

  • They do not react with air and water which are essential for corrosion.
  • They do not react even in the presence of strong and concentrated chemicals such as acids present in cleansing agents, pickles etc.
  • Food can be stored in plastic containers in spite of the chemicals present in the food.
  • Buckets which are made of iron rust over time but plastic buckets do not rust.

Question 11

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

Ans11.

No. The handles and bristles of a tooth brush should not be made of the same material because the handle should be hard and strong for better handling and grip whereas the bristles should be soft and flexible promoting easy cleanliness and preventing damage to the gums.

Question 12

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

Ans12.

We should avoid using plastics as far as possible because they are promoter of environmental pollution. Plastics are non- biodegradable. They take several years to decompose and even upon incineration they produce gases such as carbon monoxide which are hazardous to human health as well as promote global warming. Plastic bags used for carrying groceries and other items are thrown by people into the environment and are later on consumed by stray animals which may result in blocking their respiratory passage and ultimately lead to their deaths.

Question 13

Match the terms of column I correctly with the phrases given in column II.

mtc ques

 Answer 13.

mtc answer

 Question 14

‘Manufacturing synthetic fibres is actually helping conservation of forest’.

Comment.

Answer 14.

Yes, manufacturing synthetic fibres is actually helping in the conservation of forests because synthetic fibres are made from the materials which are not available in the forests and are made from manmade or artificial compounds. On the other hand, natural fibres are derived from plants and animals, so they ultimately lead to the cutting of tress and the killing of animals. Thus, synthetic fibres prevent this from happening and help preserve the ecosystem.

Question 15

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

Answer 15.

In order to show that thermoplastic is a poor conductor of electricity we can make use of a circuit as shown below:

image

It can be clearly seen in the image above that in one circuit a conductor is used whereas in the other circuit a thermosetting plastic is used in place of it,

The circuit in which the thermosetting plastic is used, the bulb does not glow proving that there is no flow of current providing the conclusion that thermosetting plastic is a poor conductor or insulator of electricity.

Topics Covered in Chapter 3 Synthetic Fibres and Plastics Class 8 Science :-

  • What are Synthetic Fibres?
  • Types of Synthetic Fibres
  • Characteristics of Synthetic Fibres
  • Plastics
  • Plastics as Materials of Choice
  • Plastics and the Environment




Important Terms Relevant to understand NCERT Solutions for Class 8 Science Chapter 3 Synthetic Fibres and Plastics:-

Synthetic Fibres: These are fibres which are made by the human beings through chemical synthesis and are not obtained naturally.

Polymer: A Polymer is a combination of various repeating sub-units joined together. They may be synthetic and may also occur in nature.

Rayon: It is also known as artificial silk and is a semi-synthetic fibre. Rayon is made from the purified cellulose fibre obtained naturally from wood pulp, but certain chemicals are also used in completing its production.

Nylon: It was first made in 1931 using nothing but coal, air and water. It was the first fully synthetic fibre, made up of long heavy chain of atoms. It is strong, elastic, lustrous, and easy to wash.

PET: It stands for Polyethylene terephthalate and is one of the most commonly used thermoplastic polymer resin used in various applications such as clothing, manufacturing, thermoforming etc.

Petrochemicals: These are the chemical compounds obtained from petroleum by refining. All synthetic fibres are derived from the petroleum origin.

Acrylic: It is more commonly known as ‘plexiglass’. It is a synthetic thermoplastic polymer that has many unique properties such as extreme strength, stiffness etc.

Polythene: It is the most commonly used plastic and is a polymer of ethylene gas. It exists as Low-Density Polythene (LDPE), High-Density Polythene (HDPE) etc. Used for various daily activities.

Thermoplastics: These are the plastic polymers that melt on heating but solidify almost indiscriminately on cooling, regaining its mechanical properties.

Thermosetting: These are cross-linked polymers that become extremely rigid upon heating and cannot be returned back to their original state.

Biodegradable: These are the substances which get degraded and decomposed upon the action of microorganisms such as bacteria. Those which do not get decomposed are known as non-biodegradable.

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