NCERT Solutions for Class 8 Science Chapter 3 Synthetic Fibres and Plastics
NCERT Solutions for Class 8 Science Chapter 3 Synthetic Fibres and Plastics are available here. Here we have provided the best and error-free solutions that will strengthen your foundation in science. Solving NCERT questions will assist you in grasping the content in the Crop Production and Management chapter in a better way.
In these solutions, we have answered all the intext and exercise questions provided in NCERT class 8 science textbook. All the solutions provided in this article are strictly based on the CBSE syllabus and curriculum. Students can easily download these solutions in PDF format for free or can read them online.
NCERT Solutions for Class 8 Science Chapter 3 Free PDF Download
Question 1: Explain why some fibres are called synthetic.
Answer: There are some fibres that are prepared by men by using chemicals. These are called synthetic fibres. These are made of small units that join together to form long chains. Examples of synthetic fibres are rayon, nylon, polyester, acrylic, etc.
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 synthesised from raw material called ______.
(c) Like synthetic fibres, plastic is also a ______.
(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: Nylon fibres are very strong. It is used for making ropes used for climbing rocks and for making parachutes. Their usage shows that nylon fibres have high tensile strength.
Question 5: Explain why plastic containers are favoured for storing food.
Answer: Plastic containers are favoured for storing food for the following reasons:
- Plastic containers are lightweight so they are easy to handle.
- The price of plastic containers is very less as compared to other containers.
- They have good strength.
- Plastic containers are durable.
Question 6: Explain the difference between the thermoplastic and thermosetting plastics.
Answer: Difference between the thermoplastic and thermosetting plastics:
|Plastic which gets deformed easily on heating and can be bent easily are known as thermoplastics.||Plastics which when moulded once, cannot be softened by heating. These are called thermosetting plastics.|
|Polythene and PVC are some of the examples of thermoplastics.||Two examples are Bakelite and Melamine.|
|These are used for manufacturing toys, combs and various types of containers.||Bakelite is used for making electrical switches, handles of various utensils, etc. Melamine is used for making floor tiles, kitchenware and fabrics which resist fire.|
Question 7: Explain why the following are made of thermosetting plastics.
(a) Saucepan handles
(b) Electric plugs/switches/plug boards
(a) Saucepan handles are made of thermosetting plastics because these plastics do not get softened on heating. Also, thermosetting plastics such as bakelite are poor conductors of heat.
(b) Thermosetting plastics such as bakelite are poor conductors of heat and electricity. Therefore, they are used for making electric plugs, switches, plugboards, etc.
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 and electrical switches.
|Can be Recycled||Cannot be recycled|
|Plastic chairs||Cooker handles|
|Plastic bowls||Electrical switches|
|The plastic covering on electrical wires|
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: Rana is advised to buy a cotton shirt for summers because cotton absorbs the sweat and the pores in cotton allow easy evaporation and keep our body cool, whereas synthetic shirts don’t absorb sweat so, they are very uncomfortable to wear in summers.
Question 10: Give examples to show that plastics are noncorrosive in nature.
Answer: Plastics are non-corrosive in nature, they do not react even if they come in contact with strong chemicals. For example, the cleaning chemicals that we use at home are stored in plastic bottles, instead of metal containers.
Question 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 toothbrush should be made of different materials. The handle of a toothbrush should be hard and strong, while the bristles should be soft and flexible.
Question 12: ‘Avoid plastics as far as possible’. Comment on this advice.
Answer: Plastics are non-biodegradable. Once introduced into the environment, they take several years to decompose. Plastics add to environmental pollution. They cannot be burnt as when burnt, they release poisonous gases. Plastic bags thrown in the garbage dump are swallowed by animals like cows. These plastic bags choke their respiratory system and can even prove fatal. Therefore, we should avoid plastics as far as possible.
Question 13: Match the terms of column I correctly with the phrases given in column II.
|(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 cookwares|
|(iv) Nylon||(d) Fabrics do not wrinkle easily|
|(i) Polyester||(d) Fabrics do not wrinkle easily|
|(ii) Teflon||(c) Used to make non-stick cookwares|
|(iii) Rayon||(a) Prepared by using wood pulp|
|(iv) Nylon||(b) Used for making parachutes and stockings|
Question 14: ‘Manufacturing synthetic fibres is actually helping conservation of forests’. Comment.
Answer: The manufacturing of synthetic fibres is helpful in the conservation of forests because if we use natural fibres, the raw materials for them have to be derived from the plants, which require cutting off lots of trees. This proves to be helpful in the conservation of forests.
Question 15: Describe an activity to show that thermoplastic is a poor conductor of electricity.
Answer: In order to show that thermoplastic is a poor conductor of electricity, we will design a circuit. For that, we need a bulb, some wires, a battery, a piece of metal and a plastic pipe (as shown in the figure below). After setting the experiment 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.
CBSE Class 8 NCERT solutions Science Chapter 3 PDF
Below we have listed the topics discussed in NCERT Solutions for Class 8 Science Chapter 3. The list gives you a quick look at the different topics and subtopics of this chapter.
|Section in NCERT Book||Topics Discussed|
|3.1||What are Synthetic Fibres?|
|3.2||Types of Synthetic Fibres|
|3.3||Characteristics of Synthetic Fibres|
|3.5||Plastics as Materials of Choice|
|3.6||Plastics and the Environment|
NCERT Solutions for Class 8 Science Chapter 3 – A Brief Discussion
CBSE Class 8 Science NCERT Solutions Chapter 3 helps students to clear their doubts and to score good marks in the board exam. All the questions are solved by experts with a detailed explanation that will help students complete their assignments & homework. Having a good grasp over CBSE NCERT Solutions for Class 8 Science will further help the students in their preparation for board exams and other competitive exams such as NTSE, Olympiad, etc. Students must also check our NCERT Solutions for Class 8 Maths and other chapters of science to score excellent marks in the exams.
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