Another way to prevent getting this page in the future is to use Privacy Pass. The shopkeeper showed her blankets made up of acrylic fibres as well as made up of wool. Why? (a) Non-reactive The chemical formula for melamine formaldehyde is C4H6N6O. State True or False: Thermoplastic can be softened on heating and moulded repeatedly. TRUE ? Which is a thermosetting plastic? FALSE; Plastic is suitable for building large and heavy structures. 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. It is, therefore, known as artificial silk. Substance used as synthetic wool. (a) Thermosetting plastics remain hard on reheating and can sustain high temperatures. 5. (a) Melamine (b) Polythene – The resin of thermosetting plastic is linear or with branched chain, after curing, (c) PVC, polythene, bakelite Question 2. Answer. Melamine is (a) thermoplastic polymer (b) thermosetting polymer (c) fibre (d) elastomer. Plastics can be easily moulded, so they are used to make a large variety of articles (or objects) having different shapes and sizes. 3. (c) nylon and cotton (d) polyester and cotton Write True or False against the following statements: a) Polyester shrinks on washing. Answer. Name two thermosetting plastic items. Thus, cause environmental pollution. Down Question. (d) Aluminium can (a) Nylon, tprylene, wool Write full forms of: a) P.V.C. 19 Rohit took with him some nylon ropes, when he was going for rock climbing. 26 Write the importance of synthetic polymers in our life. (b) Thermoplastics become soft on heating. (c) (a)-(ii), (b)-(i), (c)-(iii) Prior to curing, the reinforcement substrate is dipped into the resin binder in its liquified form. Question. 18 A bucket made of plastic does not rust like a bucket made up of iron. a) Saucepan handles. 10. Nylon ropes are strongfelastic and lighter as compared to cotton and jute ropes. Acrylic It is used for sweaters, track suits, linings for boots and gloves and In furnishing fabrics and carpets. 3 Polycot is obtained by mixing Answer. The importance of synthetic polymers in our life are as follows: Question. (c) polyester (d) terylene 7 Which of the following is not a common property of plastics? Answer. Electrical insulator and tableware. Answer. The raw material to make plastic is oil. • Melamine formaldehyde is a thermosetting plastic and cannot be melted. (a) Melamine (c) PVC (b) Polythene (d) Nylon 5. What is its common name? (a) paper (b) woollen clothes 15 Plastic is used for making a large variety of articles of daily use and these articles are very attractive. NCERT Exemplar SolutionsNCERT Exemplar MathsNCERT Exemplar Science. Answer. Question. 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. TRUE ? Very Short Answer Type Questions Answer: (b) thermosetting polymer Acrylic, polyethylene and polystyrene are thermoplastic. A) PVC B) Polythene C) Bakelite D) None of these 19. State whether the given statement is true or false. Short Answer Questions: Why should we not use plastics? (b) Cotton, polycot, rayon Initially, the polymer is a liquid or soft solid. Question. Can you write the major difference between these two types of plastics? 28 Write an activity to show that synthetic fibres are stronger than the cotton fibres. Answer. Answer. They can be easily washed at home. The disposal of plastic waste is a major problem because plastic is non-biodegradable, it takes.several years to decompose. Answer. Thermosetting plastics are normally made up of lines of polymers which are highly cross-linked. A) true B) false 17. Which synthetic fibre is called synthetic silk? Thermosetting Plastics:There are some plastics which when moulded once cannot be softened by heating. Answer. 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Can you tell why he selected nylon ropes instead of ropes made up of cotton or jute? Can you suggest some methods to limit its consumption? (d) melamine. Question. 29 Crossword Puzzle Complete the crossword given below with the help of clues. 13 Terrycot is made by mixing two types of fibres. e) P.V.C. Question. Question. Question. The molder can remove the part from the mold before it cools. (c) Durable Question. It is made without using any natural raw material. Multiple Choice Questions (a)—(iii), (b)—(iv), (c)—(v), (d)—(ii), (e)-(i), Question. is a good conductor of plastics. Melamine resin or melamine formaldehyde (also shortened to melamine) is a hard, thermosetting plastic material made from melamine and formaldehyde by polymerization. Question. Choose the correct answer: Example of thermosetting plastic is . 5. (b) Rayon resembles silk in appearance, therefore, rayon is also called artificial silk. 7. Terrycot is made by mixing terylene and cotton. A polymer used for making ropes. c) Acrilon is pure wool obtained from sheep. A thermosetting plastic is a polymer that irreversibly becomes rigid when heated. (d) (a)-(iii), (b)-(ii), (c)-(i) Question 3. Melamine plastic, also known as melamine formaldehyde, is a hard, thermosetting plastic material made from melamine and formaldehyde. Answer. These dinner plates by Carlisle feature a white body with a multi-coloured mosaic effect around the rim; they are perfect for meeting the tough demands of everyday use in schools, hospitals and care homes. View Answer. Such a material is also known as a thermoset or thermosetting polymer. Plastic containers seem most convenient. 17 Select the articles from the following list which are biodegradable. (a) PVC (b) acrylic Activity Take threads of cotton and nylon (synthetic fibres) of about same length and thickness.. FALSE; Epoxy resin is a thermoplastic? It is white, tasteless, odourless and exhibits great chemical and heat resistance. A synthetic fibre classified as polyester. Thermoplastics —–>Polythene and PVC ‘ It resists fire and can tolerate heat better than other plastics. What is its chemical name? Thermosetting plastics 5. 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 … Answer: True. (9) Melamine is … Question. Which is a thermosetting plastic? So, it is not advisable to dispose of the used plastic articles by burning. (d) PET is ‘poly-ethylene’ terephthalate’ PET as a plastic is very light weight and is commonly used for making kitchen containers. False, most of the plastics are non-biodegradable. This material is called thermosetting plastic. 11 Cotton is a natural polymer. 5 The material similar to silk in appearance is Once cured, the plastic will become hard. 4. 5 The material similar to silk in appearance is … Wood, paper, woolen clothes, aluminum can 3. Also write the false statements in their correct form. (a) (a)-(ii), (b)-(iii), (c)-(i) TRUE ? Whether a saucepan can be used in an oven usually depends on the type of material from which the pan's handles are made. Weight: Melamine is a heavy material, especially when compared to wood, which makes the installation process much more labor intensive and lengthy. (f) Peels of vegetables (7) (c) wood (f) peels of vegetables. 4. 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. Nylon It is used for making ropes for rock climbing, fishing nets, raincoats, parachutes and tyre cords, etc. Why is it so? Question. Long Answer Type Questions 14 Plastic articles are available in all possible shapes and sizes. Answer. (b) Nylon Is a synthetic fibre. (c) Wood (c) Terylene (d) Plastic It is used for making floor tiles, kitchenware and fabrics which resist fire. (a) Melamine (b) Polythene (c) PVC (d) Nylon. (e) Polyester (f) Teflon. Silk 6. • Answer: (False) Correct statement: It is good to wear clothes made of fibres while cooking. Answer. Thermoset plastic products are typically produced by heating liquid or powder within a mold and allowing the material to cure into its hardened form. (a) Cotton (b) Nylon (c)Jute (d)Wool Can you guess why? On the other hand, thermosetting plastics when moulded once cannot be softened on heating. Answer. (d) Plastics are non-reactive, light in weight and durable but they do not conduct electricity. (a) nylon (b) rayon Why? The material similar to silk in appearance is ... Indicate whether the following statements are True or False. ? (a) Melamine is a thermosetting plastic which when moulded once, cannot be softened by heating. Completing the CAPTCHA proves you are a human and gives you temporary access to the web property. Answer. Attach a pan at the other end of the thread. Answer. 20 A lady went to the market to buy a blanket. Answer. Refuse (avoid) is the best way to manage plastic. Across It is prepared from coal, water and air. Examples are bakelite and melamine. True, a disadvantage as synthetic fibre is that they melt on heating. Melamine-Formaldehyde Resins Properties. These are called thermosetting plastics e.g., bakelite and melamine. 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. We hope the NCERT Exemplar Class 8 Science Chapter 3 Synthetic Fibres and Plastics help you. The material similar to silk in appearance is (a) Nylon (c) Polyester ... Indicate whether the following statements are True or False. (a) Wool (b) PET (c) Wood pulp (d) Silk Which is a thermosetting plastic? Can you tell why? (a) Rayon (b) Polymer 12 A synthetic fibre which looks like silk is obtained by chemical treatment of wood pulp. This causes a great problem in the disposal of plastic wastes. Why do we use melamine for making kitchenware? Question 4. For this reason, thermoset materials are typically considered to be non-recyclables. Chemical name of natural polymer of cotton is cellulose. Answer. Bakelite is used for making electrical switches, handles of various utensils etc. Please enable Cookies and reload the page. Answer. Question. Add weights, one by one, to the pan until the thread breaks (see fig.) She preferred to buy an acrylic blanket. It is also mixed with natural fibre like cotton and wool to make more variety of clothes. (i) The fabric terywool is obtained by mixing terylene and wool. 25 State whether the following statements are True/False. Question. (e) Plastic bag When first heated to a certain temperature, the plastic can soften, flow and undergo a chemical reaction. Short Answer Type Questions Disadvantages of Melamine Cabinets. Name one natural fibre. Repeat the same with nylon thread. Cotton, jute and wool are natural fibres. words given below, related to synthetic Conclusion d) Bakelite is a thermoplastics plastics. Answer. (5) Question. Its common name is rayon. 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. ? 2 Which of the following is a source of rayon? TRUE ? Its physical properties and appearance has made it a popular material for manufacturing hard wearing products across a number of industries. (a) nylon and wool (b) polyester and wool NCERT Solutions for Class 6, 7, 8, 9, 10, 11 and 12. (e) Yespolter (f) Felton 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. Question. Soln: Answer is (b) Rayon A type of fibre obtained naturally from cocoon. But it is advised to avoid the use of plastic as far as possible. This gives a measure of the tensile strength of the thread. Question. 16. 27 Despite being very useful, it is advised to restrict the use of plastic. So, it is not advisable to burn plastic and synthetic fibres. Write the names of the fibres. Cloudflare Ray ID: 6076c08d7e3f1f95 State True or False: Thermoplastics are hard and brittle. (b) (a)-(iii), (b)-(i), (c)-(ii) Question. (b) Electric plugs/ switches/ plug boards are saucepan is made of thermosetting plastic because it is a bad conductor of electricity. Substance made up of large number of smaller molecules. Answer. Soln: Answer is (a) Melamine. Answer. 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. 2. Polycot, Polywool, Terrycot ,Acrylic State whether the given statements are true or false… Plastic is non-reactive material. 10 The material which is commonly used for making kitchen containers is The material similar to silk in appearance is (a) Nylon (b) Rayon (c) Polyester (d) Terylene. b) Plastics are not affected by heat. 1 Pick the synthetic fibre out of the following. When left exposed to moisture and air, it does not react with air and water which are essential for corrosion, therefore does not rust. You may need to download version 2.0 now from the Chrome Web Store. Answer. Statement: The articles made of thermoplastics can be recycled whereas the articles made of thermosetting plastics cannot be recycled. Terylene It is used in textile industry to make clothes like sarees, tapestry and dress material. (c) teflon (d) PET 4 Which is a thermosetting plastic? Box Quantity: 48. Thermosetting polymer composites are made using a laminating process, which binds together resins such as epoxy, silicone, melamine, etc. Question. Answer: Melamine is a versatile material. Acrylic blankets are cheap, light in weight, more durable and are available in variety of colours and designs. 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