Video Explanation. 15. Why are the chemicals in the laboratory stored in plastic containers ? 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. Look for models … Write two important properties of bakelite. Learn more. Q. 13. 2. True 9. (b) Melamine (c) PET (d) Polyester. Bakelite definition: 1. a brand name for a type of hard plastic used especially in the past: 2. a brand name for a type…. 14. You will often notice the heavier feel of Bakelite. Bakelite is the first synthetic plastic and is known as a “material of thousand uses” due to its versatile applications. Thermoplastic: Plastics that can be deformed easily upon heating and can be bent easily. J. Bentley, in Paint and Surface Coatings (Second Edition), 1999. Answer: (b) Melamine. False 6. Q. True 5. what  are the wide range of synthetic or semi-synthetic organic compounds that are malleable and so can be molded into solid objects Bakelite -- Bakelite is the most common material used in older American-made plastic Mah Jongg tiles. C. Bakelite and melamine both are thermoplastics. MCQ Questions for Class 12 Chemistry with Answers were prepared based on the latest exam pattern. Example : Polyethene, Polyvinyl chloride (PVC) etc. False 2. Bakelite is used for making electrical switches whereas melamine is used for floor tiles. Given one example of each. >urea-formaldehyde resin, and melamine-formaldehyde resin—are widely used as adhesives in plywood and other structural wood products. Answer: (d) Bakelite. (a) Saucepan handles (b) Electric plugs/switches/plug boards. 54) Thermopalstics can be softened by heat but thermosetting plastics cannot be softened by heat. Bakelite is an item a jewelry collector should keep an eye out for considering how prices have risen over the last few decades. Jammu & Kashmir has banned the use of plastic bags. Polythene and PVC are some of the examples of thermoplastics. Ans.Bakelite and melamine. 12. 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. Melamine is a compound used in some plastic products, such as dishes, utensils, and more. 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. For example, glycerol [5], isocyanate [6] as well as substituted melamine [7] had been added into MF resin to improve its flexibility. The result is a hard plastic material. Identify the name of the polymer. We'll discuss whether it's safe to use and any risks. See more. It came in several colors, including translucent and marbled shades by the 1950s. Question 25. 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 thermosetting phenol formaldehyde resin, formed from a condensation reaction of phenol with formaldehyde. A. Melamine is a thermoplastic whereas bakelite is a thermosetting plastic. 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. Example: Bakelite, melamine, etc. Examples: PVC and Polythene are used for manufacturing combs, toys, car grills and various type of containers. 29-5D Urea-Methanal and Melamine Resins. Melamine is resistant to fire and is hence used for making utensils. In 1927 the Bakelite patent expired. Bakelite is used for making electrical switches and switchboards because it is a poor conductor of heat and electricity. Answer: Thermosetting – bakelite, melamine Thermoplastics – combs, toys. Answer: Plastics are non-reactive, so they can be used for storing chemicals. False 3. B. Bakelite and melamine both are thermosetting plastics. False 10. Answer: 1. The classic example is Bakelite, the phenol/formaldehyde-based resin invented by the Belgian chemist Baekeland in the early 20th century. Design and technology: Pupils can revise or learn about thermosetting plastics including; Epoxy resin, Melamine formaldehyde, Polyester resin, Urea formaldehyde and Bakelite, etc. There are several variables in the method of polymerization, depending on the properties desired. We have provided Polymers Class 12 Chemistry MCQs Questions with Answers to help students understand the concept very well. Thermosetting plastic: Plastics which do not get deformed or softened on heating when mold once, are called thermosetting plastics. Bakelite's molding process had a number of advantages. 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. Preview this quiz on Quizizz. 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. Identify the type of plastic that can best be used to make electrical switches. 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. Answer: Melamine is a versatile material. Hence, option C is correct. For example: - Bakelite and Melamine. Answer. True 4. Two example of thermosetting plastics are : Bekalite and melamine. 12. 11. Example : Bakelite, Melamine etc. 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. (a) PVC (b) Polythene (c) PET (d) Bakelite. Bakelite is a thermosetting plastic, it cannot be molded again whereas Melamine, being a thermoplastic, can be molded any number of times adn reshaped. For example, Bakelite jewelry is more rare than, say, … Question 14. The market value is extremely high, due to the retro feel and limited quantities of certain products. Check the below NCERT MCQ Questions for Class 12 Chemistry Chapter 15 Polymers with Answers Pdf free download. Write some uses of Bakelite. It is also heat resistant and used for making electrical switches, handles of various utensils, etc. True 11. Bakelite and melamine are thermoplastics. Bakelite jewelry became immensely popular in the 1920s as an affordable and attractive replacement for other materials. It was the first truly synthetic plastic and was developed and patented by Leo Baekeland in 1907. If plastics are burnt, they evolve oxygen gas. 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. Synthetic fibres are moth and insect resistant. 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 Question 13. 3. For example, melamine has an annual replacement rate of around 10 to 20%, whereas china has a replacement rate between 50 and 150%. Bakelite feels heavier when compared to some other types of plastics, like celluloid as one example. 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. 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. searches to solve its rigidity problem. Ans. Bakelite is a poor conductor of electricity. 33. Ans. 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. In the first half of the 20th century they were made into very important plastics such as Bakelite and Beetleware.… 20. Bakelite is a condensation polymer that requires two monomers - phenol and formaldehyde. 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. 2.10.4 Uses. Bakelite and melamine are the examples of thermosetting plastics. 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. Question 7: Explain why the following are made of thermosetting plastics. Plastics are corrosive in nature. Candidates can download NCERT Exemplar Class 12 Chemistry Chapter 15 from this page. Explain the difference between thermoplastics and thermosetting plastics. 10. Bakelite and melamine are examples of thermosetting plastic. Answer. Today, part of the reason why Bakelite items are collectibles, are because of the fine artisanship. These cannot be re-melted. It was made from a mixture of phenol (carbolic acid) and formaldehyde. Bakelite is a man-made (synthetic) material while Melamine occurs naturally (is organic). False 8. 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. Answered By (ii) It is heat resistant. Modern non-stick cookware and the flat end of an electric iron has a coating of a polymer. Q. 11. It can be explained as follows : both the two plastics are made up of long chain molecules called polumers. 21. It resists fire and can tolerate heat better than other plastics. Classify the following into thermosetting and thermoplastics-combs, bakelite, melamine, toys. True 7. Today, formica and medium density fiberboard (MDF) are still made by mixing bakelite with paper pulp or … The formation process of these two types of plastics also differs. 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. 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