A thermosetting polymer, resin, or plastic, often called a thermoset, is a polymer that is irreversibly hardened by curing from a soft solid or viscous liquid prepolymer or resin. 9 Which of the following groups contains all synthetic substances? Silk 6. Answer. Also write the false statements in their correct form. She preferred to buy an acrylic blanket. Answer. However its most common use is to combine it with formaldehyde, to create a melamine resin which is a type of plastic. (i) The fabric terywool is obtained by mixing terylene and wool. (d) melamine. (e) Yespolter (f) Felton Question. Melamine formaldehyde is a thermosetting plastic and cannot be melted. Thermoplastics get deformed easily on heating and can be bent easily on heating. Answer. Polycot, Polywool, Terrycot ,Acrylic State whether the given statements are true or false… Box Quantity: 48. So, it is not advisable to dispose of the used plastic articles by burning. b) Plastics are not affected by heat. A type of fibre obtained naturally from cocoon. 2 Which of the following is a source of rayon? A) true B) false 18. 7. Question. Conclusion It is made from melamine and formaldehyde by condensation of the two monomers. It resists fire and can tolerate heat better than other plastics. Write the names of the fibres. Codes • 27 Despite being very useful, it is advised to restrict the use of plastic. The chemical formula for melamine formaldehyde is C4H6N6O. Name two thermosetting plastic items. Cloudflare Ray ID: 6076c08d7e3f1f95 The articles mades of plastics are non-biodegradable. The material similar to silk in appearance is (a) Nylon (b) Rayon (c) Polyester (d) Terylene. Examples are bakelite and melamine. Please enable Cookies and reload the page. Refuse (avoid) is the best way to manage plastic. 24 Unscramble the jumbled materials. So, we should avoid use of plastics, as for as possible. A lot of plastic pollutes our environment. (a) PVC (b) acrylic Which is a thermosetting plastic? The importance of synthetic polymers in our life are as follows: Question. A) true B) false 17. e) P.V.C. Melamine is … Statement: The articles made of thermoplastics can be recycled whereas the articles made of thermosetting plastics cannot be recycled. As the containers used for microwave cooking should be able to sustain reheating without causing any damage to the food kept in them, these containers can be made of thermosetting plastics. 4 Which is a thermosetting plastic? Answer. (a) paper (b) woollen clothes Question. Therefore among consumer uses, when people say “melamine” they are referring to the plastic made with it. 14 Plastic articles are available in all possible shapes and sizes. A polymer used for making ropes. 3 Polycot is obtained by mixing (a) Anory (b) Lopmery Is melamine plastic? But it is advised to avoid the use of plastic as far as possible. Silk, jute, Nylon, wool 4. The heavily cross-linked structure produced by chemical bonds in thermoset materials is directly responsible for the high mechanical and physical strength compared with thermoplastics or elastomers. (a) Melamine is a thermosetting plastic which when moulded once, cannot be softened by heating. Answer. 15 Plastic is used for making a large variety of articles of daily use and these articles are very attractive. Wood, paper, woolen clothes, aluminum can 3. Answer. (c) Durable So, it is not advisable to burn plastic and synthetic fibres. MEDIUM This causes a great problem in the disposal of plastic wastes. Down The burning of plastic wastes gives out harmful gases which pollute the air. (5) Question. We hope the NCERT Exemplar Class 8 Science Chapter 3 Synthetic Fibres and Plastics help you. Substance used as synthetic wool. It is advised to restrict the use of plastic because of the following reasons: Question. Add weights, one by one, to the pan until the thread breaks (see fig.) 9. Why? (a) Melamine (c) PVC (b) Polythene (d) Nylon . Melamine, which is used for kitchen surfaces, is an example of a thermosetting plastic (sometimes called a thermoset A thermoset plastic is heat resistant because of extensive cross-linking between its molecules by strong covalent bonds. 23 Match items in Column A with the terms of Column B. (d) PET is ‘poly-ethylene’ terephthalate’ PET as a plastic is very light weight and is commonly used for making kitchen containers. Electrical insulator and tableware. The correct matching is as given: Another way to prevent getting this page in the future is to use Privacy Pass. Can you tell why he selected nylon ropes instead of ropes made up of cotton or jute? d) Bakelite is a thermoplastics plastics. Terylene It is used in textile industry to make clothes like sarees, tapestry and dress material. Which synthetic fibre is called synthetic silk? Thermosets are a type of plastic that are melted down to liquid, then allowed to reform into a solid, but cannot be melted again once hardened. (e) Plastic bag Can you tell why? NCERT Exemplar Class 8 Science Chapter 3 Synthetic Fibres and Plasticst are part of NCERT Exemplar Class 8 Science. Question. Choose the correct answer: Example of thermosetting plastic is . Nylon It is used for making ropes for rock climbing, fishing nets, raincoats, parachutes and tyre cords, etc. Melamine resin or melamine formaldehyde (also shortened to melamine) is a resin with melamine rings terminated with multiple hydroxyl groups derived from formaldehyde.This thermosetting plastic material is made from melamine and formaldehyde. 17 Select the articles from the following list which are biodegradable. Melamine plastics degrade and release chemical constituents upon heating to temperatures utilized for cooking in ovens and microwaves, as well as upon exposure to acidic foodstuffs. 1. Question 2. Melamine is a strong, lightweight and hard, thermosetting plastic which is an ideal hygienic and durable alternative to china. Question. Answer. NCERT Exemplar SolutionsNCERT Exemplar MathsNCERT Exemplar Science. The material similar to silk in appearance is ... Indicate whether the following statements are True or False. Can you guess why? The shopkeeper showed her blankets made up of acrylic fibres as well as made up of wool. Much more weight is required to break the nylon thread showing that nylon thread has a grater strength that the cotton thread. 18 A bucket made of plastic does not rust like a bucket made up of iron. Once cured, the plastic will become hard. (f) Peels of vegetables (a)—(iii), (b)—(iv), (c)—(v), (d)—(ii), (e)-(i), Question. Can you suggest some methods to limit its consumption? The raw material to make plastic is oil. (c) PVC, polythene, bakelite (c) Nylon —-> Fibre , PVC —->Thermoplastic , Bakelite —->Thermosetting plastic. Write full forms of: a) P.V.C. Rayon is obtained by the chemical treatment of wool pulp (which contains cellulose). Answer. A) PVC B) Polythene C) Bakelite D) None of these 19. Question. Thermoset plastic products are typically produced by heating liquid or powder within a mold and allowing the material to cure into its hardened form. False, most of the plastics are non-biodegradable. (c) PVC, polythene and bakelite are synthetic substances. Curing is induced by heat or suitable radiation and may be promoted by high pressure, or mixing with a catalyst.Heat is not necessarily to be applied externally. Thermosetting polymer composites are made using a laminating process, which binds together resins such as epoxy, silicone, melamine, etc. (c) nylon (d) bakelite Answer: True. While p olyethylene is a thermoplastic polymer consisting of long hydrocarbon chains, PVC or Polyvinyl chloride , is also a thermoplastic produced by polymerization of vinyl chloride monomer (VCM) and nylon belongs to a … Your IP: 188.8.131.52 (a) Wool (b) PET (c) Wood pulp (d) Silk (c) wood (f) peels of vegetables. What is its common name? (c) Terylene (d) Plastic Nylon ropes are strongfelastic and lighter as compared to cotton and jute ropes. (4) FALSE; PVC is a thermoplastic. 6 The most suitable material for the preparation of handles of cooking utensils is (a) polythene (b) PVC When first heated to a certain temperature, the plastic can soften, flow and undergo a chemical reaction. 4. (d) Good conductor of electricity Polycot = polyester + cotton. The reaction used to produce thermosetting plastic products involve a chemical interaction between specialized materials. This gives a measure of the tensile strength of the thread. Explanation: Thermosetting plastics when moulded once can not be softened by heating. (a) nylon (b) rayon FALSE; Plastic is suitable for building large and heavy structures. If you have any query regarding NCERT Exemplar Class 8 Science Chapter 3 Synthetic Fibres and Plastics, drop a comment below and we will get back to you at the earliest. Answer. Answer: True. Question. (d) Acrylic, silk, wool Repeat the same with nylon thread. You may need to download version 2.0 now from the Chrome Web Store. c) Acrilon is pure wool obtained from sheep. Multiple Choice Questions Answer. The resin of thermosetting plastic is linear or with branched chain, after curing, note the total weight required to break the cotton thread. Rayon is often regarded as artificial silk. Answer. Terrycot is made by mixing terylene and cotton. FALSE; HDPE is a tough plastic used for making toys. Plastic is non-reactive material. If you are on a personal connection, like at home, you can run an anti-virus scan on your device to make sure it is not infected with malware. (b) Cotton, polycot, rayon Such a material is also known as a thermoset or thermosetting polymer. 11. Question 4. Whether a saucepan can be used in an oven usually depends on the type of material from which the pan's handles are made. Melamine-Formaldehyde Resins Properties. 13 Terrycot is made by mixing two types of fibres. with reinforcement base materials such as glass, linen and graphite. View Answer. Question. Thermosetting plastics are normally made up of lines of polymers which are highly cross-linked. (a) Paper 16 Why is it not advisable to burn plastic and synthetic fabrics? It is used for making floor tiles, kitchenware and fabrics which resist fire. (c) Relyteen (d) Laspict Question. Chemical name of natural polymer of cotton is cellulose. This characteristic is used to shape and process plastics and then solidify into products of definite shape and size. (a) Melamine (b) Polythene – True or False : Question 1. Thermosetting plastics 5. is a good conductor of plastics. Question. 21 PVC (polyvinyl chloride) is a thermoplastic and is used for making toys, chappals, etc. Question. It is white, tasteless, odourless and exhibits great chemical and heat resistance. 12 A synthetic fibre which looks like silk is obtained by chemical treatment of wood pulp. (a) (a)-(ii), (b)-(iii), (c)-(i) The material similar to silk in appearance is (a) Nylon (c) Polyester ... Indicate whether the following statements are True or False. (b) Thermoplastics become soft on heating. 26 Write the importance of synthetic polymers in our life. It is made without using any natural raw material. (d) Polycot is obtained by mixing polyester and cotton. (a) Nylon, tprylene, wool Disadvantages of Melamine Cabinets. (e) Polyester (f) Teflon. ? This material is called thermosetting plastic. Bakelite is a thermosetting plastic and is used for making electrical switches, handles of various utensils, etc. (c) PVC (d) Nylon Its physical properties and appearance has made it a popular material for manufacturing hard wearing products across a number of industries. Prior to curing, the reinforcement substrate is dipped into the resin binder in its liquified form. Answer. If you are at an office or shared network, you can ask the network administrator to run a scan across the network looking for misconfigured or infected devices. Short Answer Type Questions NCERT Solutions for Class 6, 7, 8, 9, 10, 11 and 12. Answer. Performance & security by Cloudflare, Please complete the security check to access. Answer. (d) Plastics are non-reactive, light in weight and durable but they do not conduct electricity. A nylon thread is actually stronger than a steel wire of similar thickness. Acrylic It is used for sweaters, track suits, linings for boots and gloves and In furnishing fabrics and carpets. Initially, the polymer is a liquid or soft solid. (a) Melamine (c) PVC (b) Polythene (d) Nylon 5. (c) teflon (d) PET Question. 2. Completing the CAPTCHA proves you are a human and gives you temporary access to the web property. (b) Woollen clothes Filed Under: CBSE Tagged With: CBSE 8 Synthetic Fibres and Plastics., CBSE Exemplar Problems Class 8 Science, RD Sharma Class 11 Solutions Free PDF Download, NCERT Solutions for Class 12 Computer Science (Python), NCERT Solutions for Class 12 Computer Science (C++), NCERT Solutions for Class 12 Business Studies, NCERT Solutions for Class 12 Micro Economics, NCERT Solutions for Class 12 Macro Economics, NCERT Solutions for Class 12 Entrepreneurship, NCERT Solutions for Class 12 Political Science, NCERT Solutions for Class 11 Computer Science (Python), NCERT Solutions for Class 11 Business Studies, NCERT Solutions for Class 11 Entrepreneurship, NCERT Solutions for Class 11 Political Science, NCERT Solutions for Class 11 Indian Economic Development, NCERT Solutions for Class 10 Social Science, NCERT Solutions For Class 10 Hindi Sanchayan, NCERT Solutions For Class 10 Hindi Sparsh, NCERT Solutions For Class 10 Hindi Kshitiz, NCERT Solutions For Class 10 Hindi Kritika, NCERT Solutions for Class 10 Foundation of Information Technology, NCERT Solutions for Class 9 Social Science, NCERT Solutions for Class 9 Foundation of IT, PS Verma and VK Agarwal Biology Class 9 Solutions, Chapter 4 Materials : Metals and Non-Metals, Chapter 7 Conservation of Plants and Animals, Chapter 10 Reaching the Age of Adolescence, Chapter 14 Chemical Effects of Electric Current, NCERT Solutions for Class 10 Science Chapter 1, NCERT Solutions for Class 10 Science Chapter 2, Periodic Classification of Elements Class 10, NCERT Solutions for Class 10 Science Chapter 7, NCERT Solutions for Class 10 Science Chapter 8, NCERT Solutions for Class 10 Science Chapter 9, NCERT Solutions for Class 10 Science Chapter 10, NCERT Solutions for Class 10 Science Chapter 11, NCERT Solutions for Class 10 Science Chapter 12, NCERT Solutions for Class 10 Science Chapter 13, NCERT Solutions for Class 10 Science Chapter 14, NCERT Solutions for Class 10 Science Chapter 15, NCERT Solutions for Class 10 Science Chapter 16, CBSE Previous Year Question Papers Class 12, CBSE Previous Year Question Papers Class 10. 19 Rohit took with him some nylon ropes, when he was going for rock climbing. Question. Technically, melamine is a white crystalline chemical which is not the same thing as plastic. (b) Rayon resembles silk in appearance, therefore, rayon is also called artificial silk. Burning of plastics and synthetic fabrics produces lots of poisonous gases causing air pollution. Soln: Answer is (a) Melamine. Thermoplastics —–>Polythene and PVC ‘ Melamine is (a) thermoplastic polymer (b) thermosetting polymer (c) fibre (d) elastomer. State, whether the following statements are True or False. Rayon 7.Which raw material is used to make nylon? It is good to wear clothes made of synthetic fibres while cooking. Why is it so? (b) (a)-(iii), (b)-(i), (c)-(ii) Question. 1. 5. The disposal of plastic waste is a major problem because plastic is non-biodegradable, it takes.several years to decompose. Answer. (d) Bakelite is used for making the handles of various cooking utensils because it is a poor conductor of heat and does not become soft on getting heated. Which is a thermosetting plastic? (d) (a)-(iii), (b)-(ii), (c)-(i) A synthetic fibre classified as polyester. words given below, related to synthetic Substance made up of large number of smaller molecules. For this reason, thermoset materials are typically considered to be non-recyclables. ? State True or False: Thermoplastics are hard and brittle. Can you write the major difference between these two types of plastics? Soln: Answer is (b) Rayon It is also mixed with natural fibre like cotton and wool to make more variety of clothes. Name one natural fibre. Answer: (False) Correct statement: It is good to wear clothes made of fibres while cooking. Bakelite is used for making electrical switches, handles of various utensils etc. a) Saucepan handles. Melamine resin or melamine formaldehyde (also shortened to melamine) is a hard, thermosetting plastic material made from melamine and formaldehyde by polymerization. A plastic used for making containers and carry bags. Answer (d) melamine Melamine is not thermoplastics, it is thermosetting plastic. The molder can remove the part from the mold before it cools. Also write the false statements in their correct form. On the other hand, thermosetting plastics when moulded once cannot be softened on heating.