Answer: 1. The exemplar has been provided by the National Council of Educational Research & Training (NCERT) and the candidates can check it from below for free of cost. You will often notice the heavier feel of Bakelite. Plus, melamine is relatively resistant to scratch marks from forks, knives, and other utensils. Tamilnadu Samacheer Kalvi 7th Science Solutions Term 3 Chapter 3 Polymer Chemistry If plastics are burnt, they evolve oxygen gas. 2.10.4 Uses. Q. True 11. Bakelite and melamine are thermoplastics. Video Explanation. Answered By Answer: Melamine is a versatile material. Answer: Plastics are non-reactive, so they can be used for storing chemicals. False 6. Look for models … False 2. Q. False 10. Molded Bakelite forms in a condensation reaction of phenol and formaldehyde, with wood flour or asbestos fiber as a filler, under high pressure and heat in a time frame of a few minutes of curing. Learn more. Design and technology: Pupils can revise or learn about thermosetting plastics including; Epoxy resin, Melamine formaldehyde, Polyester resin, Urea formaldehyde and Bakelite, etc. T h e r m o p l a s t i c s: These are the plastics which get deformed easily on heating and can be bent easily. False 3. Candidates can download NCERT Exemplar Class 12 Chemistry Chapter 15 from this page. True 9. 13. Why are the chemicals in the laboratory stored in plastic containers ? Question 7: Explain why the following are made of thermosetting plastics. Synthetic fibres are moth and insect resistant. Bakelite definition, a brand name for any of a series of thermosetting plastics prepared by heating phenol or cresol with formaldehyde and ammonia under pressure: used for radio cabinets, telephone receivers, electric insulators, and molded plastic ware. Today, part of the reason why Bakelite items are collectibles, are because of the fine artisanship. Bakelite is a thermosetting plastic, it cannot be molded again whereas Melamine, being a thermoplastic, can be molded any number of times adn reshaped. Write two important properties of bakelite. For example, melamine has an annual replacement rate of around 10 to 20%, whereas china has a replacement rate between 50 and 150%. 12. Jammu & Kashmir has banned the use of plastic bags. Question 14. A. Melamine is a thermoplastic whereas bakelite is a thermosetting plastic. In 1927 the Bakelite patent expired. For example, glycerol [5], isocyanate [6] as well as substituted melamine [7] had been added into MF resin to improve its flexibility. Bakelite is used for making electrical switches whereas melamine is used for floor tiles. Two example of thermosetting plastics are : Bekalite and melamine. Identify the type of plastic that can best be used to make electrical switches. C. Bakelite and melamine both are thermoplastics. (a) Saucepan handles (b) Electric plugs/switches/plug boards. Given one example of each. The market value is extremely high, due to the retro feel and limited quantities of certain products. Thermosetting plastic: Plastics which do not get deformed or softened on heating when mold once, are called thermosetting plastics. Answer. 21. Melamine is resistant to fire and is hence used for making utensils. Bakelite and melamine are the examples of thermosetting plastics. Example: Bakelite, melamine, etc. Question 13. Bakelite is an item a jewelry collector should keep an eye out for considering how prices have risen over the last few decades. Ans. 15. Answer: Thermosetting – bakelite, melamine Thermoplastics – combs, toys. 29-5D Urea-Methanal and Melamine Resins. True 7. Plastics are corrosive in nature. Pupils can then try the ‘quiz time’ questions to test their thermosetting plastic knowledge. 33. Bakelite is a condensation polymer that requires two monomers - phenol and formaldehyde. MCQ Questions for Class 12 Chemistry with Answers were prepared based on the latest exam pattern. Bakelite jewelry became immensely popular in the 1920s as an affordable and attractive replacement for other materials. (ii) It is heat resistant. Hence, option C is correct. Ans. Hold another type of plastic you have identified in one hand, and a piece you know to be Bakelite of approximately the same size in the other. Today, formica and medium density fiberboard (MDF) are still made by mixing bakelite with paper pulp or … (a) PVC (b) Polythene (c) PET (d) Bakelite. Melamine / ˈ m ɛ l ə m iː n / is an organic compound with the formula C 3 H 6 N 6.This white solid is a trimer of cyanamide, with a 1,3,5-triazine skeleton. Q. Students can Download Science Chapter 3 Polymer Chemistry Questions and Answers, Notes Pdf, Samacheer Kalvi 7th Science Book Solutions Guide Pdf helps you to revise the complete Tamilnadu State Board New Syllabus and score more marks in your examinations. Bakelite feels heavier when compared to some other types of plastics, like celluloid as one example. Bakelite is the first synthetic plastic and is known as a “material of thousand uses” due to its versatile applications. Answer. Bakelite is a thermosetting phenol formaldehyde resin, formed from a condensation reaction of phenol with formaldehyde. Bakelite's molding process had a number of advantages. We have provided Polymers Class 12 Chemistry MCQs Questions with Answers to help students understand the concept very well. Ans.Bakelite and melamine. The classic example is Bakelite, the phenol/formaldehyde-based resin invented by the Belgian chemist Baekeland in the early 20th century. Answer: (b) Melamine. See more. Answer: (d) Bakelite. 14. There are several variables in the method of polymerization, depending on the properties desired. Key Difference – Bakelite vs Plastic Plastic and Bakelite are both organic polymers, having a very large molecular weight though there exists a difference between the two based on their properties and usage. searches to solve its rigidity problem. It can be explained as follows : both the two plastics are made up of long chain molecules called polumers. (i) It is a poor conductor of electricity. We'll discuss whether it's safe to use and any risks. Bakelite is a poor conductor of electricity. These cannot be re-melted. B. Bakelite and melamine both are thermosetting plastics. It was the first truly synthetic plastic and was developed and patented by Leo Baekeland in 1907. As we all know, emulsifier can reduce the interfacial tension and increase the contact area between foaming agent and MF resin which is benefit to foaming. Bakelite definition: 1. a brand name for a type of hard plastic used especially in the past: 2. a brand name for a type…. 20. In the growing consumer market of the 1930s and after, Bakelite faced competition from other thermosetting resins such as urea formaldehyde and melamine formaldehyde and from new thermoplastic resins such as cellulose acetate, polyvinyl chloride, polymethyl methacrylate, and polystyrene. It was made from a mixture of phenol (carbolic acid) and formaldehyde. Melamine formaldehyde (MF) resins MF resins have similar properties to UF resins, but they are tougher and more thermally stable and chemically resistant. Bakelite is a man-made (synthetic) material while Melamine occurs naturally (is organic). what  are the wide range of synthetic or semi-synthetic organic compounds that are malleable and so can be molded into solid objects D. Bakelite is a thermoplastic whereas melamine is a thermosetting plastic. Polythene and PVC are some of the examples of thermoplastics. (b) Melamine (c) PET (d) Polyester. The formation process of these two types of plastics also differs. True 5. 11. Example : Bakelite, Melamine etc. Bakelite -- Bakelite is the most common material used in older American-made plastic Mah Jongg tiles. 2. For example, Bakelite jewelry is more rare than, say, … Melamine is a compound used in some plastic products, such as dishes, utensils, and more. 54) Thermopalstics can be softened by heat but thermosetting plastics cannot be softened by heat. Authentic bakelite jewelry can sell for thousands of dollars, so it's important you learn how to tell the difference between genuine and imposter plastic jewelry. MF resins are used for higher end applications like laminates for countertops and cabinets and surface coatings for automobiles that require a binder with good cosmetic characteristics. It came in several colors, including translucent and marbled shades by the 1950s. Explain the difference between thermoplastics and thermosetting plastics. Thermosetting polymers : These are semifluid substances with low molecular masses which when heated in a mould, undergo change in chemical composition to give a hard, infusible and insoluble mass. The result is a hard plastic material. Check the below NCERT MCQ Questions for Class 12 Chemistry Chapter 15 Polymers with Answers Pdf free download. Bakelite and melamine are examples of thermosetting plastic. True 4. Write some uses of Bakelite. It resists fire and can tolerate heat better than other plastics. Like cyanamide, it contains 67% nitrogen by mass, and its derivatives have fire retardant properties due to its release of nitrogen gas when burned or charred. Question 25. Identify the name of the polymer. In the first half of the 20th century they were made into very important plastics such as Bakelite and Beetleware.… Examples: PVC and Polythene are used for manufacturing combs, toys, car grills and various type of containers. False 8. 12. For example: - Bakelite and Melamine. Thermoplastic: Plastics that can be deformed easily upon heating and can be bent easily. Classify the following into thermosetting and thermoplastics-combs, bakelite, melamine, toys. Compared to bakelite, melamine is lighter and more elastic and therefore can be used with thinner objects, for example, in games and models, as well as for creating bijoux and accessories for clothes. 10. Consider the weight of a piece of plastic jewelry. Preview this quiz on Quizizz. >urea-formaldehyde resin, and melamine-formaldehyde resin—are widely used as adhesives in plywood and other structural wood products. J. Bentley, in Paint and Surface Coatings (Second Edition), 1999. Syntheses of a number of polymers are based on condensation of methanal with amino compounds by mechanisms at least formally analogous to those involved in the preparation of Bakelite resins. 3. Modern non-stick cookware and the flat end of an electric iron has a coating of a polymer. 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