Soln: Answer is (a) Melamine. The resin of thermosetting plastic is linear or with branched chain, after curing, Answer. 1. (c) Terylene (d) Plastic (7) (a) (a)-(ii), (b)-(iii), (c)-(i) Attach a pan at the other end of the thread. Question. (b) (a)-(iii), (b)-(i), (c)-(ii) Answer. True, a disadvantage as synthetic fibre is that they melt on heating. Soln: Answer is (b) Rayon Silk, jute, Nylon, wool 4. Thermosetting plastics do not melt when heated. • 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. Your IP: 138.201.32.27 A) true B) false 18. TRUE ? (c) teflon (d) PET Conclusion Which is a thermosetting plastic? Answer. Question. 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. NCERT Exemplar Class 8 Science Chapter 3 Synthetic Fibres and Plasticst are part of NCERT Exemplar Class 8 Science. (c) Wool pulp 6 The most suitable material for the preparation of handles of cooking utensils is (a) polythene (b) PVC Short Answer Questions: Why should we not use plastics? 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. Answer. 3 Polycot is obtained by mixing 10. 13 Terrycot is made by mixing two types of fibres. Question. This material is called thermosetting plastic. Across Can you guess why? Question. 19 Rohit took with him some nylon ropes, when he was going for rock climbing. Acrylic, polyethylene and polystyrene are thermoplastic. The importance of synthetic polymers in our life are as follows: Question. Question. (a) paper (b) woollen clothes (d) Good conductor of electricity (b) Light in weight • Answer. Terylene It is used in textile industry to make clothes like sarees, tapestry and dress material. 7. Write the names of the fibres. 5 The material similar to silk in appearance is … 5. 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. Why? Melamine plastic, also known as melamine formaldehyde, is a hard, thermosetting plastic material made from melamine and formaldehyde. (a) Nylon, tprylene, wool Plastics It is used to store food item, water, milk, pickles, dry food, etc. It is advised to restrict the use of plastic because of the following reasons: Question. 9. 9 Which of the following groups contains all synthetic substances? Question. Answer. It is used for making floor tiles, kitchenware and fabrics which resist fire. Answer. Melamine-Formaldehyde Resins Properties. A lot of plastic pollutes our environment. (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. 24 Unscramble the jumbled materials. 27 Despite being very useful, it is advised to restrict the use of plastic. A plastic used for making containers and carry bags. 5 The material similar to silk in appearance is (b) Cotton, polycot, rayon words given below, related to synthetic The material similar to silk in appearance is (a) Nylon (b) Rayon (c) Polyester (d) Terylene. FALSE; PVC is a thermoplastic. Also write the false statements in their correct form. Answer. Answer. She preferred to buy an acrylic blanket. Substance used as synthetic wool. 2 Which of the following is a source of rayon? 17 Select the articles from the following list which are biodegradable. Thermoplastics —–>Polythene and PVC ‘ Thermosetting plastics 5. 5. TRUE ? Answer: True. Answer. This results in increased installation costs, which may affect a homeowner's ability to afford these types of kitchen cabinets. Explanation: Thermosetting plastics when moulded once can not be softened by heating. d) Bakelite is a thermoplastics plastics. State whether the given statement is true or false. (8) The reaction used to produce thermosetting plastic products involve a chemical interaction between specialized materials. Answer. A synthetic fibre classified as polyester. Write full forms of: a) P.V.C. FALSE; HDPE is a tough plastic used for making toys. Write True or False against the following statements: a) Polyester shrinks on washing. Therefore among consumer uses, when people say “melamine” they are referring to the plastic made with it. Short Answer Type Questions What is its chemical name? ? Question. (a) Wool (b) PET (c) Wood pulp (d) Silk Its common name is rayon. with reinforcement base materials such as glass, linen and graphite. 15 Plastic is used for making a large variety of articles of daily use and these articles are very attractive. (e) Yespolter (f) Felton Question. (d) Plastics are non-reactive, light in weight and durable but they do not conduct electricity. (9) Question. A) true B) false 17. ? You may need to download version 2.0 now from the Chrome Web Store. Burning of plastics and synthetic fabrics produces lots of poisonous gases causing air pollution. They tend to char and burn when heated, but they are resistant to much higher temperatures than thermosoftening plastics. Polycot = polyester + cotton. Terrycot is made by mixing terylene and cotton. is a good conductor of plastics. Bakelite is used for making electrical switches, handles of various utensils etc. (7) ? (d) (a)-(iii), (b)-(ii), (c)-(i) (a) nylon and wool (b) polyester and wool Plastic containers seem most convenient. Melamine formaldehyde is a thermosetting plastic and cannot be melted. Here we have given NCERT Exemplar Class 8 Science Chapter 3 Synthetic Fibres and Plastics. Answer. A) PVC B) Polythene C) Bakelite D) None of these 19. Statement: The articles made of thermoplastics can be recycled whereas the articles made of thermosetting plastics cannot be recycled. (5) Answer. Plastics can be easily moulded, so they are used to make a large variety of articles (or objects) having different shapes and sizes. (d) PET is ‘poly-ethylene’ terephthalate’ PET as a plastic is very light weight and is commonly used for making kitchen containers. Question 4. Examples are bakelite and melamine. A nylon thread is actually stronger than a steel wire of similar thickness. 1. Answer: (False) Correct statement: It is good to wear clothes made of fibres while cooking. (a) Cotton (b) Nylon (c)Jute (d)Wool (a) Melamine (c) PVC (b) Polythene (d) Nylon . When left exposed to moisture and air, it does not react with air and water which are essential for corrosion, therefore does not rust. Question 2. Rayon is often regarded as artificial silk. State True or False: Thermoplastic can be softened on heating and moulded repeatedly. The molder can remove the part from the mold before it cools. (a) PVC (b) acrylic Long Answer Type Questions (a) Melamine (b) Polythene – The shopkeeper showed her blankets made up of acrylic fibres as well as made up of wool. Answer. 7 Which of the following is not a common property of plastics? Initially, the polymer is a liquid or soft solid. Answer. Thermosetting plastics —–> Bakelite and melamine, Question. The articles mades of plastics are non-biodegradable. 4. NCERT Solutions for Class 6, 7, 8, 9, 10, 11 and 12. It is white, tasteless, odourless and exhibits great chemical and heat resistance. (c) polyester (d) terylene Electrical insulator and tableware. Question. Question. This gives a measure of the tensile strength of the thread. (c) Wood Thermoset plastic products are typically produced by heating liquid or powder within a mold and allowing the material to cure into its hardened form. Question 3. (b) Nylon Is a synthetic fibre. 1 Pick the synthetic fibre out of the following. The biodegradable articles are: The burning of plastic wastes gives out harmful gases which pollute the air. Answer (d) melamine Melamine is not thermoplastics, it is thermosetting plastic. note the total weight required to break the cotton thread. (i) The fabric terywool is obtained by mixing terylene and wool. ? III. Another name for this compound is artificial silk. (a) Thermosetting plastics remain hard on reheating and can sustain high temperatures. 25 State whether the following statements are True/False. 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. Plastic is non-reactive material. When first heated to a certain temperature, the plastic can soften, flow and undergo a chemical reaction. Is melamine plastic? Which is a thermosetting plastic? Rayon 7.Which raw material is used to make nylon? Nylon ropes are strongfelastic and lighter as compared to cotton and jute ropes. These are called thermosetting plastics e.g., bakelite and melamine. (b) Rayon resembles silk in appearance, therefore, rayon is also called artificial silk. 14 Plastic articles are available in all possible shapes and sizes. Answer. (a) Melamine is a thermosetting plastic which when moulded once, cannot be softened by heating. Add weights, one by one, to the pan until the thread breaks (see fig.) Down Answer: True. (c) PVC, polythene and bakelite are synthetic substances. Very Short Answer Type Questions Polycot, Polywool, Terrycot ,Acrylic State whether the given statements are true or false… Question. 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. Acrylic blankets are cheap, light in weight, more durable and are available in variety of colours and designs. Question. ? (a) Rayon (b) Polymer (c) nylon (d) bakelite Answer. Can you suggest some methods to limit its consumption? (c) PVC, polythene, bakelite Why? Thermosetting Plastics:There are some plastics which when moulded once cannot be softened by heating. Cloudflare Ray ID: 6076c08d7e3f1f95 Answer. Which synthetic fibre is called synthetic silk? (a) Anory (b) Lopmery Completing the CAPTCHA proves you are a human and gives you temporary access to the web property. 11. Cotton, jute and wool are natural fibres. The disposal of plastic waste is a major problem because plastic is non-biodegradable, it takes.several years to decompose. (c) PVC (d) Nylon Answer. Performance & security by Cloudflare, Please complete the security check to access. Also write the false statements in their correct form. Answer: (b) thermosetting polymer They can be easily washed at home. 10 The material which is commonly used for making kitchen containers is Disadvantages of Melamine Cabinets. The raw material to make plastic is oil. The material similar to silk in appearance is ... Indicate whether the following statements are True or False. They do not decompose (or rot) easily. (e) Plastic bag (c) Relyteen (d) Laspict 21 PVC (polyvinyl chloride) is a thermoplastic and is used for making toys, chappals, etc. 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. 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. It is also mixed with natural fibre like cotton and wool to make more variety of clothes. 18 A bucket made of plastic does not rust like a bucket made up of iron. Answer. c) Acrilon is pure wool obtained from sheep. A thermosetting plastic is a polymer that irreversibly becomes rigid when heated. (d) Polycot is obtained by mixing polyester and cotton. (b) Thermoplastics become soft on heating. NCERT Exemplar SolutionsNCERT Exemplar MathsNCERT Exemplar Science. Nylon It is used for making ropes for rock climbing, fishing nets, raincoats, parachutes and tyre cords, etc. Thermosetting polymer composites are made using a laminating process, which binds together resins such as epoxy, silicone, melamine, etc. 16 Why is it not advisable to burn plastic and synthetic fabrics? Question. Please enable Cookies and reload the page. So, we should avoid use of plastics, as for as possible. Name two thermosetting plastic items. Silk 6. Why is it so? Answer. On the other hand, thermosetting plastics when moulded once cannot be softened on heating. Question. Refuse (avoid) is the best way to manage plastic. Melamine is (a) thermoplastic polymer (b) thermosetting polymer (c) fibre (d) elastomer. (b) Electric plugs/ switches/ plug boards are saucepan is made of thermosetting plastic because it is a bad conductor of electricity. Answer. 20 A lady went to the market to buy a blanket. TRUE ? 11 Cotton is a natural polymer. (5) (c) nylon and cotton (d) polyester and cotton Weight: Melamine is a heavy material, especially when compared to wood, which makes the installation process much more labor intensive and lengthy. Question. a) Saucepan handles. Another way to prevent getting this page in the future is to use Privacy Pass. So, it is not advisable to dispose of the used plastic articles by burning. Can you tell why? Substance made up of large number of smaller molecules. 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. (e) Polyester (f) Teflon. 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 … Can you write the major difference between these two types of plastics? 23 Match items in Column A with the terms of Column B. 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. Its physical properties and appearance has made it a popular material for manufacturing hard wearing products across a number of industries. 26 Write the importance of synthetic polymers in our life. What is its common name? (a) nylon (b) rayon Question. FALSE; Epoxy resin is a thermoplastic? (c) wood (f) peels of vegetables. 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. Answer: Melamine is a versatile material. (f) Peels of vegetables It is made without using any natural raw material. 16. For this reason, thermoset materials are typically considered to be non-recyclables. It is made from melamine and formaldehyde by condensation of the two monomers. Answer. Thermoplastics get deformed easily on heating and can be bent easily on heating. Question. Answer. Repeat the same with nylon thread. 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. (a) Melamine (b) Polythene (c) PVC (d) Nylon. 2. Answer. Much more weight is required to break the nylon thread showing that nylon thread has a grater strength that the cotton thread. (a) Paper A polymer used for making ropes. It is good to wear clothes made of synthetic fibres while cooking. Prior to curing, the reinforcement substrate is dipped into the resin binder in its liquified form. (d) Acrylic, silk, wool Thermosetting plastics are normally made up of lines of polymers which are highly cross-linked. 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. We hope the NCERT Exemplar Class 8 Science Chapter 3 Synthetic Fibres and Plastics help you. View Answer. 4 Which is a thermosetting plastic? 12 A synthetic fibre which looks like silk is obtained by chemical treatment of wood pulp. The chemical formula for melamine formaldehyde is C4H6N6O. State, whether the following statements are True or False. Answer 4 (a) Question 5. Question. (b) Woollen clothes Answer. Hang cotton, thread from a stand. (d) Aluminium can (a)—(iii), (b)—(iv), (c)—(v), (d)—(ii), (e)-(i), Question. Such a material is also known as a thermoset or thermosetting polymer. Choose the correct answer: Example of thermosetting plastic is . Thus, cause environmental pollution. Wood, paper, woolen clothes, aluminum can 3. 4. Question. Teflon (b) Electric switches (c) Pa rachutes (d) Polyester (e) Artificial silk The odd one out. Melamine crockery is a thermoset plastic resin made from organic compounds. Question. TRUE ? Rayon is obtained by the chemical treatment of wool pulp (which contains cellulose). PVC, melamine, polythene, natural ru bber 2. Answer. So, it is not advisable to burn plastic and synthetic fibres. Question. (a) Non-reactive b) Plastics are not affected by heat. (c) Durable Codes 29 Crossword Puzzle Complete the crossword given below with the help of clues. e) P.V.C. True or False : Question 1. (4) 3. It is, therefore, known as artificial silk. Chemical name of natural polymer of cotton is cellulose. Can you tell why he selected nylon ropes instead of ropes made up of cotton or jute? > Polythene and PVC ‘ thermosetting plastics: There are some plastics which moulded... Natural polymer of cotton and wool to make nylon plastics remain hard on reheating can. Making electrical switches, handles of various utensils, etc not conduct electricity substrate is dipped the! Polymer is a thermosetting plastic is non-biodegradable, it is good to wear clothes made synthetic... Required to break the nylon thread has a grater strength that the fibres! • Performance & security by cloudflare, Please complete the security check to access products across a number industries., known as artificial silk and durable alternative to china fibre out of the thread security by cloudflare, complete! High temperatures problem because plastic is suitable for building large and heavy structures steel wire of similar thickness be. Great chemical and heat resistance track suits, linings for boots and gloves and in furnishing fabrics carpets. Her blankets made up of lines of polymers which are biodegradable is linear or branched... Common use is to combine it with formaldehyde, to the web property silicone,,. Formaldehyde, is a source of Rayon a measure of the used plastic articles are very.! And dress material by heating correct form woolen clothes, aluminum can.. ) paper ( b ) nylon —- > thermosetting plastic is actually stronger than a steel wire similar... Page in the future is to use Privacy Pass ( or rot ) easily plastics —– > and... Went to the web property irreversibly becomes rigid when heated ( b ) Electric plugs/ switches/ boards. Oven usually depends on the type of plastic as far as possible once, can not be softened on.. Plastic is used for making toys of vegetables certain temperature, the polymer a! Two monomers None of these 19 than the cotton fibres as glass, linen and graphite the... Resembles silk in appearance, therefore, Rayon is also known as a or! For rock climbing, fishing nets, raincoats, parachutes and tyre cords, etc: Question handles are.... Melamine is a white crystalline chemical which is a thermosetting plastic, flow and undergo a chemical reaction to.! Represents the correct Answer: ( a ) melamine ( b ) Rayon ( b ) PET ( )!, light in weight ( c ) Polyester ( d ) melamine melamine is a tough used... In the future is to combine it with formaldehyde, to the market to buy blanket. Natural fibre like cotton and wool gives a measure of the two monomers with the help of clues nylon instead... Life are as follows: Question to show that synthetic fibres are than! It resists fire and can not be softened on heating and moulded repeatedly saucepan is of. Following represents the correct Answer: ( False ) correct statement: it is for..., it is made of thermosetting plastic is a type of material from the... Does not rust like a bucket made of plastic waste is a of... For sweaters, track suits, linings for boots and gloves and in furnishing fabrics carpets! This reason, thermoset materials are typically considered to be non-recyclables and durable but they referring! A pan at the other hand, thermosetting plastic products involve a chemical reaction made from organic.... Or soft solid a human and gives you temporary access to the pan the. And fabrics which resist fire represents the correct Answer: ( False ) correct statement: it used!, Rayon is also mixed with natural fibre like cotton and jute ropes Electric plugs/ switches/ plug boards are is!
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