(5) (c) PVC (d) Nylon Question. (8) Bakelite is used for making electrical switches, handles of various utensils etc. A lot of plastic pollutes our environment. ? 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. (d) (a)-(iii), (b)-(ii), (c)-(i) Short Answer Type Questions 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. ? 4. Answer. Hang cotton, thread from a stand. It is also mixed with natural fibre like cotton and wool to make more variety of clothes. (c) wood (f) peels of vegetables. Rayon 7.Which raw material is used to make nylon? (e) Plastic bag Box Quantity: 48. Cotton, jute and wool are natural fibres. 4. (7) (c) Relyteen (d) Laspict For this reason, thermoset materials are typically considered to be non-recyclables. (a) Melamine (b) Polythene (c) PVC (d) Nylon. (d) PET is ‘poly-ethylene’ terephthalate’ PET as a plastic is very light weight and is commonly used for making kitchen containers. Answer: (False) Correct statement: It is good to wear clothes made of fibres while cooking. Such a material is also known as a thermoset or thermosetting polymer. Answer. (4) (a) Cotton (b) Nylon (c)Jute (d)Wool What is its common name? Melamine crockery is a thermoset plastic resin made from organic compounds. Answer. 1. Initially, the polymer is a liquid or soft solid. Answer. TRUE ? 15 Plastic is used for making a large variety of articles of daily use and these articles are very attractive. III. Electrical insulator and tableware. A type of fibre obtained naturally from cocoon. What is its chemical name? Answer. View Answer. 23 Match items in Column A with the terms of Column B. Attach a pan at the other end of the thread. Thermosetting plastics 5. Answer. Much more weight is required to break the nylon thread showing that nylon thread has a grater strength that the cotton thread. (b) Thermoplastics become soft on heating. NCERT Exemplar Class 8 Science Chapter 3 Synthetic Fibres and Plasticst are part of NCERT Exemplar Class 8 Science. Its physical properties and appearance has made it a popular material for manufacturing hard wearing products across a number of industries. Question. Question. 2. Here we have given NCERT Exemplar Class 8 Science Chapter 3 Synthetic Fibres and Plastics. Question. (b) Woollen clothes 1 Pick the synthetic fibre out of the following. (c) PVC, polythene, bakelite words given below, related to synthetic 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. 8 Which of the following represents the correct match for items in Column A with those in Column B. A plastic used for making containers and carry bags. Question. (a) Melamine (c) PVC (b) Polythene (d) Nylon 5. Heat provides energy for chemical reactions that increase the cross-linking Long Answer Type Questions Can you tell why? A polymer used for making ropes. The raw material to make plastic is oil. Explanation: Thermosetting plastics when moulded once can not be softened by heating. Another way to prevent getting this page in the future is to use Privacy Pass. Terylene It is used in textile industry to make clothes like sarees, tapestry and dress material. This characteristic is used to shape and process plastics and then solidify into products of definite shape and size. Answer. • Answer. (d) Polycot is obtained by mixing polyester and cotton. 6 The most suitable material for the preparation of handles of cooking utensils is (a) polythene (b) PVC Thus, cause environmental pollution. Once cured, the plastic will become hard. The material similar to silk in appearance is (a) Nylon (c) Polyester ... Indicate whether the following statements are True or False. 26 Write the importance of synthetic polymers in our life. 13 Terrycot is made by mixing two types of fibres. Which synthetic fibre is called synthetic silk? Answer. Thermosetting plastics are normally made up of lines of polymers which are highly cross-linked. A synthetic fibre classified as polyester. This results in increased installation costs, which may affect a homeowner's ability to afford these types of kitchen cabinets. The shopkeeper showed her blankets made up of acrylic fibres as well as made up of wool. Question. • State, whether the following statements are True or False. ? Question. NCERT Solutions for Class 6, 7, 8, 9, 10, 11 and 12. Answer. Answer. Codes 18 A bucket made of plastic does not rust like a bucket made up of iron. You may need to download version 2.0 now from the Chrome Web Store. 4. (a) Anory (b) Lopmery Please enable Cookies and reload the page. (c) Wool pulp True, a disadvantage as synthetic fibre is that they melt on heating. Answer. (c) Terylene (d) Plastic 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. (a) Nylon, tprylene, wool Refuse (avoid) is the best way to manage plastic. Another name for this compound is artificial silk. As a result, there is a risk of melamine and formaldehyde discharge into foods prepared or stored in melamine-containing dishes, bowls, and other products in the home. with reinforcement base materials such as glass, linen and graphite. Question. A) true B) false 17. Soln: Answer is (a) Melamine. 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On the other hand, thermosetting plastics when moulded once cannot be softened on heating. The molder can remove the part from the mold before it cools. Technically, melamine is a white crystalline chemical which is not the same thing as plastic. The biodegradable articles are: The reaction used to produce thermosetting plastic products involve a chemical interaction between specialized materials. Multiple Choice Questions Short Answer Questions: Why should we not use plastics? The resin of thermosetting plastic is linear or with branched chain, after curing, (c) Nylon —-> Fibre , PVC —->Thermoplastic , Bakelite —->Thermosetting plastic. FALSE; HDPE is a tough plastic used for making toys. (a) (a)-(ii), (b)-(iii), (c)-(i) TRUE ? Question. 11 Cotton is a natural polymer. It is good to wear clothes made of synthetic fibres while cooking. They do not decompose (or rot) easily. The material similar to silk in appearance is ... Indicate whether the following statements are True or False. (c) Durable FALSE; Plastic is suitable for building large and heavy structures. Polycot, Polywool, Terrycot ,Acrylic State whether the given statements are true or false… 14 Plastic articles are available in all possible shapes and sizes. Why? Whether a saucepan can be used in an oven usually depends on the type of material from which the pan's handles are made. Question 4. The material similar to silk in appearance is (a) Nylon (b) Rayon (c) Polyester (d) Terylene. 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. (a) nylon and wool (b) polyester and wool Therefore among consumer uses, when people say “melamine” they are referring to the plastic made with it. Question. She preferred to buy an acrylic blanket. Answer. Cloudflare Ray ID: 6076c08d7e3f1f95 Answer: True. Question. (d) melamine. Repeat the same with nylon thread. Substance used as synthetic wool. Which is a thermosetting plastic? Answer. (a) PVC (b) acrylic Add weights, one by one, to the pan until the thread breaks (see fig.) Silk, jute, Nylon, wool 4. (a) Melamine is a thermosetting plastic which when moulded once, cannot be softened by heating. ? 5. Is melamine plastic? 25 State whether the following statements are True/False. Answer. 3 Polycot is obtained by mixing However its most common use is to combine it with formaldehyde, to create a melamine resin which is a type of plastic. Question. (7) Answer. Thermosetting polymer composites are made using a laminating process, which binds together resins such as epoxy, silicone, melamine, etc. (f) Peels of vegetables 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. Answer. 9 Which of the following groups contains all synthetic substances? Plastic containers seem most convenient. Statement: The articles made of thermoplastics can be recycled whereas the articles made of thermosetting plastics cannot be recycled. When first heated to a certain temperature, the plastic can soften, flow and undergo a chemical reaction. (d) Plastics are non-reactive, light in weight and durable but they do not conduct electricity. TRUE ? (a) Wool (b) PET (c) Wood pulp (d) Silk Bakelite is a thermosetting plastic and is used for making electrical switches, handles of various utensils, etc. 21 PVC (polyvinyl chloride) is a thermoplastic and is used for making toys, chappals, etc. (a)—(iii), (b)—(iv), (c)—(v), (d)—(ii), (e)-(i), Question. (a) Paper a) Saucepan handles. A) PVC B) Polythene C) Bakelite D) None of these 19. Answer. They tend to char and burn when heated, but they are resistant to much higher temperatures than thermosoftening plastics. PVC, melamine, polythene, natural ru bber 2. Question 3. Question. (b) Rayon resembles silk in appearance, therefore, rayon is also called artificial silk. Which is a thermosetting plastic? This gives a measure of the tensile strength of the thread. Choose the correct answer: Example of thermosetting plastic is . State True or False: Thermoplastic can be softened on heating and moulded repeatedly. State whether the given statement is true or false. Can you suggest some methods to limit its consumption? Answer: (b) thermosetting polymer Answer. The disposal of plastic waste is a major problem because plastic is non-biodegradable, it takes.several years to decompose. Thermoset plastic products are typically produced by heating liquid or powder within a mold and allowing the material to cure into its hardened form. (b) (a)-(iii), (b)-(i), (c)-(ii) 9. This causes a great problem in the disposal of plastic wastes. 11. 1. It is, therefore, known as artificial silk. Answer: Melamine is a versatile material. (9) 20 A lady went to the market to buy a blanket. (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. Nylon ropes are strongfelastic and lighter as compared to cotton and jute ropes. 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. 27 Despite being very useful, it is advised to restrict the use of plastic. 16. 17 Select the articles from the following list which are biodegradable. Its common name is rayon. Melamine is a strong, lightweight and hard, thermosetting plastic which is an ideal hygienic and durable alternative to china. Thermosetting Plastics:There are some plastics which when moulded once cannot be softened by heating. Answer (d) melamine Melamine is not thermoplastics, it is thermosetting plastic. It is made from melamine and formaldehyde by condensation of the two monomers. Thermosetting plastics do not melt when heated. d) Bakelite is a thermoplastics plastics. (a) Rayon (b) Polymer So, we should avoid use of plastics, as for as possible. (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. (a) paper (b) woollen clothes Melamine is (a) thermoplastic polymer (b) thermosetting polymer (c) fibre (d) elastomer. A) true B) false 18. (a) Non-reactive (c) (a)-(ii), (b)-(i), (c)-(iii) 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. 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. Burning of plastics and synthetic fabrics produces lots of poisonous gases causing air pollution. Teflon (b) Electric switches (c) Pa rachutes (d) Polyester (e) Artificial silk The odd one out. (c) Wood Rayon is obtained by the chemical treatment of wool pulp (which contains cellulose). Down Answer: True. A nylon thread is actually stronger than a steel wire of similar thickness. Melamine is … We hope the NCERT Exemplar Class 8 Science Chapter 3 Synthetic Fibres and Plastics help you. Question. Acrylic blankets are cheap, light in weight, more durable and are available in variety of colours and designs. It is white, tasteless, odourless and exhibits great chemical and heat resistance. Answer. Melamine plastic, also known as melamine formaldehyde, is a hard, thermosetting plastic material made from melamine and formaldehyde. Why is it so? (c) nylon and cotton (d) polyester and cotton Question 2. Across 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 … 16 Why is it not advisable to burn plastic and synthetic fabrics? Question. It is advised to restrict the use of plastic because of the following reasons: Question. 7. Plastics can be easily moulded, so they are used to make a large variety of articles (or objects) having different shapes and sizes. Answer. 12 A synthetic fibre which looks like silk is obtained by chemical treatment of wood pulp. They can be easily washed at home. Acrylic, polyethylene and polystyrene are thermoplastic. 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Are normally made up of wool pulp ( which contains cellulose ) not rust like a bucket up! By condensation of the thread advisable to burn plastic and is used for making toys chappals. Shape and process plastics and then solidify into products of definite shape and size 7 which the. Non-Reactive ( b ) Polythene ( c ) Terylene, as for as.... ) silk Answer of about same length and thickness > thermoplastic, —-.