NCERT Solution For Class 8 Science, Chapter 3 – Synthetic Fibres and Plastics

NCERT Solutions is known as an extremely helpful resource for preparing for the exam. Takshila Learning provides its learners with access to a wealth of NCERT problems and their solutions. CBSE Class 8 Science NCERT Solutions are built by subject matter experts, so be sure to train learners for a good grade. The questions set out in the NCERT Books are prepared in compliance with the requirements of the CBSE.

NCERT Solution For Class 8 Science, Chapter 3 – Synthetic Fibres and Plastics provides us with all-inclusive information on all concepts. As students would have to learn the basics about the subject in class 8, this curriculum for class 8 is comprehensive study material, which explains the concepts in a great way.

Explain why some fibres are called synthetic.

Answer:
Some fibres are called synthetic fibres because they are prepared by humans using chemicals.

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:
(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 synthesized from a raw material called _____
(c) Like synthetic fibres, plastic is also a _____

Answer:
(a) man-made, artificial fibres
(b) petrochemicals
(c) polymer

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

Answer:
The following examples indicate that nylon fibres are very strong, they are:
(i) They are basically used for making parachutes and ropes for rock climbing.
(ii) They are also used for making seat-belts, fishing nets, tire cord, a string for sports rackets and musical instruments.

Question 5.
Explain why plastic containers are favoured for storing food.

Answer:
Plastic containers are favoured for storing food because:
(i) the plastics do not respond with the food stored in them.
(ii) the plastics are light and are strong.
(iii) they are easy to deal with and safe.

Question 6.
Explain the difference between thermoplastic and thermosetting plastics.

Answer:

Question 7.
Explain why the following are made of thermosetting plastics.
(a) Saucepan handles
(b) Electric plugs/switches/plug boards

Answer:
(a) Since thermosetting plastics are a bad conductor of heat and do not get warmed while cooking, they are used for preparing saucepan handles.
(b) Since thermosetting plastics are a bad conductor of electricity and the electric current does not depart through such plastics, they are used for making electric plugs, switches, plug boards.

Question 8.
Categorize the materials of the following products into ‘can be recycled’ and ‘cannot be recycled’.
Telephone instruments, plastic toys, cooker handles, carry bags, ballpoint pens, plastic bowls, plastic covering on electrical wires, plastic chairs, electrical switches.

Answer:

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:
He should buy cotton shirts because cotton has more capability to hold moisture than synthetic clothes. In summers we have enormous sweating which is easily absorbed by cotton shirts and hence, cotton clothes are much favourable than the clothes made from synthetic material.

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

Answer:
Examples that show that plastics are non-corrosive in nature.

• Plastic containers do not respond with items stored in it.
• They do not get rusted when jeopardized to moisture and air.
• They do not deteriorate when left in open for a long period.

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

Answer:
No, the handle and bristles of a toothbrush should not be made of the same material because our gums are soft and sensitive and the bristles should be made of soft material so that it does not harm the gums. On the other hand, the handles should be made up of hard and strong material so that it can give a firm grip.

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

Answer:
Plastics must be avoided as far as possible. The stuff made of plastics is non-biodegradable. The use of plastics has a bad effect on the environment and surroundings. When the plastics are burnt, it discloses a lot of harmful fumes into the environment causing air pollution. These plastic materials when eat up by the animals (like cows) choke their respiratory system. This can result in the death of these animals. The scrap plastic items thrown here and there recklessly get into dirty water drains and sewers, and block them. In a nutshell, plastics can be considered a danger to our environment.

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

Answer:
(i) (d)
(ii) (c)
(iii) (a)
(iv) (b)

Question 14.
‘Manufacturing synthetic fibres is actually helping the conservation of forests’. Comment.

Answer:
In the manufacturing of synthetic fibres, we use only chemical substances and no biological materials, thus, in turn, we conserve forests.

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

Answer:
Arrange a circuit as shown in the given figure. Leave a gap between two ends of the wire. Place a thermoplastic in the gap. Observe the bulb.

It is observed that the bulb does not glow. This shows that thermoplastic is a poor conductor of electricity.

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