Addition polymers: Polymers are formed by the repeated addition of monomers with double and triple bonds. 1) Teflon, a kind of plastic is used as a coating to manufacture non-stick cookware. Although synthetic fibre catches fire easily, it is interesting to know that the uniforms of firemen have coating of “melamine plastic” to make them flame resistant. A common example of linear polymer A Bakelite B Melamine C Branched D Poly. “Generally, we see in a garbage dump where animals eating garbage”. Question 7. Question 12. Although rayon is obtained from a natural source, wood pulp, yet it is a man-made fibre. The fabric melts and sticks to the body of the person wearing it. Being lighter as compared to metals, plastics are used in cars, aircrafts and spacecrafts, too. a) Thermosetting plastics. Can you write a name of a “Natural polymer”? The first human-made plastics were actually made using cellulose from plants. Boojho wants to know that which type of plastic is used for the coating of uniforms of fireman? Such as animals, trees, cotton, jute. a) Nylon. So, it is quite suitable for making dress material. See more. For example, polyethene and polyvinyl chloride. v) Synthetic fibres absorb very little water. It contributes sturdy structure to the plants. Course Hero is not sponsored or endorsed by any college or university. This preview shows page 1 - 2 out of 2 pages. Answer: Plastics are non-reactive, so they can be used for storing chemicals. Question 25. We can store various kinds of chemicals and other materials in plastic containers because they are non-reactive and does not react with water and air. Why? A. Bakelite B. Melamine C. Branched D. Poly-vinyl chloride 9. Important Questions and Extra questions are prepared to revise the chapter 3 of Class 8 Science. Nylon is also used for making parachutes and ropes for rock climbing. The wool obtained from natural sources is quite expensive, whereas clothes made from acrylic are relatively cheap. Answer. Why do people choose this type of sweaters? Nylon is another man-made fibre. Polyester is another synthetic fibre. ii) Buy products without a little plastic packaging. b) Silk. Ask your doubts related to NIOS or CBSE Board and share your knowledge with your friends and other users through Discussion Forum. Such fibre was obtained by chemical treatment of wood pulp. Polyvinyl chloride has heavy metals such as cadmium and lead which are toxic and harmful to our health. So, it is not advisable to dispose of the used plastic articles by burning. A synthetic fibre is also a chain of small units joined together. Answer: Thermosetting – bakelite, melamine Thermoplastics – combs, toys. 2) Bakelite is a poor conductor of heat and electricity so, it is used for making electric switches and handles of the utensils. This is actually a disadvantage of synthetic fibres. These are prepared from a type of synthetic fibre, called acrylic. Bakelite and Melamine are examples of a) Thermosetting plastics b) Silk c) Nylon d) Rayon. Polythene and PVC are some of the examples of thermoplastics. For example, Bakelite, and Melamine formaldehyde. Fire proof plastic uniform worn by fire fighters has a coating of _____ to make it fire resistant. Hence, “manufacturing synthetic fibres is actually helping conservation of forests”. A material which gets decomposed through natural processes, such as action by bacteria, is called biodegradable. “Paheli wants to know the uses of plastic in health-care industry”. Answer: (c) 10. Explain the statement. The coating on modern non- stick cookware and electric iron is of These cannot be re-melted. Cotton is a natural polymer, called cellulose. b) Rayon. These fibres are made from petrochemicals. Some examples are natural gas or even corn, wheat, or rice. Bataan Peninsula State University in Balanga, Bataan Peninsula State University in Balanga • BSME 101, Cracking the Sat Biology E_M Su - The Princeton Review.pdf, Bataan Peninsula State University in Balanga • CEA 0223, Bataan Peninsula State University in Balanga • BSAR 13-00215, Bataan Peninsula State University in Balanga • BSME 5C, Bataan Peninsula State University in Balanga • NURSING 103, Bataan Peninsula State University in Balanga • CHEM MISC. These are called synthetic fibres. They are available in a variety of colours. Will you help her? iv) Collect and dispose of biodegradable and nonbiodegradable waste separately. Class 8 Science Chapter 3 Important Questions of Synthetic Fibres and Fabric. c) Melamine plastic. Odd one out: choose the letter of the word that is not related from the other choices. Question 13. a) Terrycot. Example : Bakelite, Melamine etc. Such as animals, trees, cotton, jute. The plastic material chokes the respiratory system of these animals, or forms a lining in their stomachs and can be the cause of their death. We should use of bags made of cotton or jute instead of plastic bags when we go for shopping. Odd one out: choose the letter of the word that is not related from the other choices. Plastics are often made from petrochemicals like crude oil but can also be made from other materials. Question 13. She preferred to buy an acrylic blanket”. The term polymer means large molecules with higher molecular mass. Therefore, this fibre is referred as artificial silk or man-made fibre. Therefore, people always prefer to choose plastic instead of using metals. These are used for manufacturing toys, combs and various types of containers. “Despite being very useful, it is advised to restrict the use of plastic”. Mention also their pattern of joining with each other. Towards the end of the nineteenth century, scientists were successful in obtaining a fibre having properties similar to that of silk. These are reactive molecules and are usually linked to each other by covalent bonds. In the process of eating the food waste from dump of garbage – “they swallow materials like polythene bags and wrappers of food”. 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. d) Silk 10 The coating on modern non- stick cookware and electric iron is of. They become hard and infusible on heating and cannot be softened again. 4) Recover: We can recover or restore the resources into their original state, wherever possible. d) Rayon 9 Fire proof plastic uniform worn by fire fighters has a coating of _____ to make it fire resistant. Some important properties of bakelite are listed below. We have provided Polymers Class 12 Chemistry MCQs Questions with Answers to help students understand the concept very well. The shopkeeper showed her blankets made up of acrylic fibres as well as made up of wool. On the other hand, there are some plastics which when moulded once, cannot be softened by heating. 3) Recycle: Resources can be recycled wherever possible so that they can be used again and again. Jammu & Kashmir has banned the use of plastic bags. It is further classified into, Homopolymers:Polymers formed by the polymerisation of a single monomeric species. A common example of linear polymer. Tutorial for Learning C Programming: Is It Possible to Learn the Programming Language Online. The chemical formula of bakelite can be written as (C 6 H 6 O-CH 2 OH) n. What are the Desirable Properties of Bakelite? Question 8. use a steel lunch box instead of a plastic one. This causes a great problem in the disposal of plastic waste. Explain. Can you suggest some methods to limit its consumption? Why is it so? Polymerization in the simplest form can be described as a chemical process that results in the formation of polymers. Although, polyester (Poly+ester) is actually made up of the repeating units of a chemical called an ester. Bakelite is a man-made (synthetic) material while Melamine occurs naturally (is organic). a) Nylon b) Rayon c) Melamine plastic d) Silk. Sometimes people are very careless and throw the wrappers of chips, biscuits and other eatables on the road or in parks or picnic places. Classify the following into thermosetting and thermoplastics-combs, bakelite, melamine, toys. Esters are the chemicals which give fruits their smell. That is why electrical wires have plastic covering, and handles of screw drivers are made of plastic. 1) Reduce: We must reduce the use of resources as possible and save them for the future generation. In 1927 the Bakelite patent expired. Define the term synthetic fibre. Such as plastic. Polymers are generally formed by the addition of a network of structural units or small molecules called monomers. How does plastic create problems for them? Synthetic fibres are more durable and affordable which makes them more popular than natural fibres. “Avoid the use of plastic as for as possible”. There are some plastic articles which can bend easily while some break when forced to bend. 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(adsbygoogle = window.adsbygoogle || []).push({}); Copyright 2021 by Tiwari Academy – A step towards Free Education, NCERT Solutions for Class 8 Science Chapter 3, Class 8 Science Chapter 3 Important Questions. Plastic causes environmental pollution. Answer: (a) 9. All organic compound comes to this category. The formation process of these two types of plastics also differs. It is used for non-stick coating on cook-wares. Try to minimise the use of plastic materials. v) Do not throw plastic waste in the street on the pavement or in drains. Bakelite and melamine are some examples of thermoplastics Answer: False Correct statement: Bakelite and and melamine are some examples of thermosettingplastic. Write down their some features. 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. This is because of their light weight, lower price, good strength and easy handling. A material which gets decomposed through natural processes, such as action by bacteria, is called biodegradable. The polybags carelessly thrown here and there are responsible for clogging the drains, too. Thermosetting polymers are those which undergo permanent change on heating. Some examples of synthetic fibres are polyester, nylon and acrylic. These monomers add together to form a long chain to form a product with spe… Many such small units combine to form a large single unit called a polymer. iii)Synthetic fibres are less expensive and readily available in the market. For manufacturing synthetic fibres cutting of trees or killing of animals is not required and we can conserve our natural environment using synthetic fibres. Generally, shirt, trousers, bed sheets, blankets, curtains, table-cloths, towels and dusters are made from different kinds of fibres. 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. Should we not think twice before doing so? Give example to show that plastics are non-corrosive in nature. Answer: True. Such as plastic. It is used for making floor tiles, kitchenware and fabrics which resist fire. Most of the thermoplastics can be recycled. Why do people always prefer to choose plastic instead of using metals? 2) The burning of plastic waste gives out harmful gases which pollute the air. “A lady went to a market to buy a blanket. It can be drawn into very fine fibres that can be woven like any other yarn. Check the below NCERT MCQ Questions for Class 12 Chemistry Chapter 15 Polymers with Answers Pdf free download. How would you contribute towards the reducing the use of plastic materials? If the clothes catch fire, it can be disastrous. It resists fire and can tolerate heat better than other plastics. These are called thermosetting plastics. A material which is not easily decomposed by natural processes is termed as non-biodegradable. Terylene is a popular polyester. Synthetic fibres melt on heating. 8 Bakelite and Melamine are examples of. How is plastic made? Download NCERT Books 2020-21 based on new CBSE Syllabus for session 2020-2021. Plastic takes several years to decompose; it is not environment friendly. Acrylic blankets are cheap, light in weight, more durable and are available in variety of colours and designs. Name some common articles made from fibres. Why are the chemicals in the laboratory stored in plastic containers ? b) Rayon. Write down their some features. After studying the NCERT Books, important Questions provide a proper revision of the chapter for exams. MCQ Questions for Class 12 Chemistry with Answers were prepared based on the latest exam pattern. Synthetic fibres possess unique characteristics which make them popular dress materials. Synthetic fibres are man-made fibres. They do not decompose (or rot) easily. Generally, people love to wearing polyester shirts and other dresses. Today if we think of storing a food item, water, milk, pickles, dry food, etc., plastic containers seem most convenient. The list is endless if we start counting articles like slippers, furniture and decoration pieces, etc. i) Avoid the use of plastics as far as possible. Teflon is a special plastic on which oil and water do not stick. After reading NCERT Books, you have just to go through these questions to prepare the entire chapter for exams. Cellulose is made up of a large number of glucose units. Fabric made from this fibre does not get wrinkled easily. i)Synthetic fibres are very strong and durable. They are not corroded easily. Question 14. Based on the mode of polymerisation, it is classified into I. We need not produce resources on large scale which may lead to exploitation of natural resources. vi)Synthetic fibre are not attacked by moths easily. A. Bakelite B. Melamine C. Branched D. Cross-linked 10. The cross-linked product of phenol and formaldehyde has the following structure. They are also referred to as macromolecules. Class 8 Science Chapter 3 Extra Questions are prepared for academic session 2020-21 and it provides the complete revision of NCERT Book of Class 8 Science Chapter 3. Melamine is a versatile material. What do you mean by “thermoplastic” and “thermosetting plastic”? ii) Synthetic fibres are light, wrinkled free and easy to maintain. “As a responsible citizen remember the 4R principle”. Would you like to help him? Can you guess why? vi) Try to minimise the use of plastic materials e.g. 3) Melamine is used for making floor tiles and kitchenware. The 4 R principle is: 4R means Reduce, Reuse, Recycle and Recover. We use many articles made from nylon, such as socks, ropes, tents, toothbrushes, car seat belts, sleeping bags, curtains etc. Example : Polyethene, Polyvinyl chloride (PVC) etc. Which type of plastic is used for non-stick coating on cook-wares? 2) Reuse: Resources can be reused wherever possible. All organic compound comes to this category. Orientation of monomer units in a polymer molecule A. Tacticity B. Graft C. Linear D. Monomer arrangement 11. Bakelite and Melamine are the example of thermosetting plastic. In the process it releases lots of poisonous fumes into the atmosphere causing air pollution. Today, formica and medium density fiberboard (MDF) are still made by mixing bakelite with paper pulp or … 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. So, a polymer is made of many repeating units. Besides, the burning process in the synthetic material is quite slow and it does not get completely burnt easily. Plastics find extensive use in the health-care industry. Answer. It is better to recycle the plastic waste. Write down some characteristics of synthetic fibre. Examples – Bakelite, melamine, etc. Do Not Burn Plastic and Synthetic Fabrics. c) Nylon. Bakelite items, particularly jewelry and radios, have become a popular collectible. Examples – Bakelite, Melamine, Silicone, Epoxy. Bakelite and Melamine are the example of thermosetting plastic. Reducing the usage is a method of conservation of resources. These two types of containers Chemistry Chapter 15 Polymers with Answers Pdf free download where animals eating garbage.. It possible to Learn the Programming Language Online, trees, cotton, jute pieces... Units joined together should, therefore, people always prefer to choose plastic instead of metals... 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bakelite and melamine are example of