Orientation of monomer units in a polymer molecule, A type of polymer wherein the side groups are arranged in an irregular or random, Monomers made of alkenes usually undergo addition polymerization due to their. It can be quickly molded. Synthetic fibres melt on heating. When we add hot water to a plastic bottle, it gets deformed. Plastics find extensive use in the health-care industry. Bakelite is a poor conductor of heat and electricity. Why do people always prefer to choose plastic instead of using metals? 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. But plastics do not react with water and air. If the clothes catch fire, it can be disastrous. She preferred to buy an acrylic blanket”. On the other hand, there are some plastics which when moulded once, cannot be softened by heating. Answer: Plastics are non-reactive, so they can be used for storing chemicals. This causes a great problem in the disposal of plastic waste. Generally, shirt, trousers, bed sheets, blankets, curtains, table-cloths, towels and dusters are made from different kinds of fibres. “Avoid the use of plastic as for as possible”. Reducing the usage is a method of conservation of resources. Explain. A common example of linear polymer. Why is it so? Bakelite and Melamine are the example of thermosetting plastic. Besides, the burning process in the synthetic material is quite slow and it does not get completely burnt easily. These are called synthetic fibres. v) Do not throw plastic waste in the street on the pavement or in drains. A material which is not easily decomposed by natural processes is termed as non-biodegradable. The term Bakelite is sometimes used in the resale market to indicate various types of early plastics, including Catalin and Faturan, which may be brightly colored, as well as items made of Bakelite material. c) Nylon. 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. Teflon is a special plastic on which oil and water do not stick. Burning of plastics and synthetic fabrics produces lots of poisonous gases causing air pollution. Polythene and PVC are some of the examples of thermoplastics. A. Bakelite B. Melamine C. Branched D. Poly-vinyl chloride 9. The term polymer means large molecules with higher molecular mass. We use many articles made from nylon, such as socks, ropes, tents, toothbrushes, car seat belts, sleeping bags, curtains etc. Answer: True. So, it is not advisable to burn plastic and synthetic fabrics. iv) Synthetic fibres are extremely fine and shiny. Why do people choose this type of sweaters? Plastic causes environmental pollution. “Generally, we see in a garbage dump where animals eating garbage”. a) Nylon b) Rayon c) Melamine plastic d) Silk. Bakelite is a man-made (synthetic) material while Melamine occurs naturally (is organic). i)Synthetic fibres are very strong and durable. Addition polymers: Polymers are formed by the repeated addition of monomers with double and triple bonds. It resists fire and can tolerate heat better than other plastics. Synthetic fibres possess unique characteristics which make them popular dress materials. Important Questions and Extra questions are prepared to revise the chapter 3 of Class 8 Science. It is advised to restrict the use of plastic because of the following reasons: 1) The articles made of plastics are non-biodegradable. Write down their some features. See more. “We should not wear synthetic clothes while working in kitchen or in the laboratory”. 4) Recover: We can recover or restore the resources into their original state, wherever possible. We should, therefore, not wear synthetic clothes while working in in the kitchen or in a laboratory. This preview shows page 1 - 2 out of 2 pages. (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. Today if we think of storing a food item, water, milk, pickles, dry food, etc., plastic containers seem most convenient. 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. d) Rayon 9 Fire proof plastic uniform worn by fire fighters has a coating of _____ to make it fire resistant. Being lighter as compared to metals, plastics are used in cars, aircrafts and spacecrafts, too. Do Not Burn Plastic and Synthetic Fabrics. “A lady went to a market to buy a blanket. For example, polyethene and polyvinyl chloride. The shopkeeper showed her blankets made up of acrylic fibres as well as made up of wool. Polyester is another synthetic fibre. 2) The burning of plastic waste gives out harmful gases which pollute the air. vi) Try to minimise the use of plastic materials e.g. Jammu & Kashmir has banned the use of plastic bags. These fibres are made from petrochemicals. 1) Teflon, a kind of plastic is used as a coating to manufacture non-stick cookware. Such as animals, trees, cotton, jute. Plastic takes several years to decompose; it is not environment friendly. Write down some characteristics of synthetic fibre. A. Bakelite B. Melamine C. Branched D. Cross-linked 10. Generally, people love to wearing polyester shirts and other dresses. A material which gets decomposed through natural processes, such as action by bacteria, is called biodegradable. We should develop habits which are environment friendly. Try to minimise the use of plastic materials. d) Silk 10 The coating on modern non- stick cookware and electric iron is of. Nylon is also used for making parachutes and ropes for rock climbing. “As a responsible citizen remember the 4R principle”. They become hard and infusible on heating and cannot be softened again. Nylon is another man-made fibre. vi)Synthetic fibre are not attacked by moths easily. Orientation of monomer units in a polymer molecule A. Tacticity B. Graft C. Linear D. Monomer arrangement 11. The cross-linked product of phenol and formaldehyde has the following structure. Should we not think twice before doing so? The fabric melts and sticks to the body of the person wearing it. 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. Metals like iron get rusted when left exposed to moisture and air. Course Hero is not sponsored or endorsed by any college or university. Polyvinyl chloride has heavy metals such as cadmium and lead which are toxic and harmful to our health. Based on the mode of polymerisation, it is classified into I. use a steel lunch box instead of a plastic one. Boojho wants to know that which type of plastic is used for the coating of uniforms of fireman? Synthetic fibres are man-made fibres. How is plastic made? Can you write a name of a “Natural polymer”? This is actually a disadvantage of synthetic fibres. Discuss. iv) Collect and dispose of biodegradable and nonbiodegradable waste separately. ii) Synthetic fibres are light, wrinkled free and easy to maintain. Examples – Bakelite, melamine, etc. The first human-made plastics were actually made using cellulose from plants. The polybags carelessly thrown here and there are responsible for clogging the drains, too. Answer: Thermosetting – bakelite, melamine Thermoplastics – combs, toys. Many such small units combine to form a large single unit called a polymer. Answer: (a) 9. 1) Reduce: We must reduce the use of resources as possible and save them for the future generation. Mention also their pattern of joining with each other. “In every year, Boojho likes to wear a sweater which appear to resemble like wool”. For example, Bakelite, and Melamine formaldehyde. There are some of the steps which contribute towards the reducing the use of plastic materials by us. Example : Polyethene, Polyvinyl chloride (PVC) etc. Why? Question 13. 3) Recycle: Resources can be recycled wherever possible so that they can be used again and again. In 1927 the Bakelite patent expired. Bakelite and Melamine are the example of thermosetting plastic. We need not produce resources on large scale which may lead to exploitation of natural resources. 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 is better to recycle the plastic waste. 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. What do you mean by “thermoplastic” and “thermosetting plastic”? Cotton is a natural polymer, called cellulose. b) Rayon. There are some plastic articles which can bend easily while some break when forced to bend. They do not decompose (or rot) easily. Hence, “manufacturing synthetic fibres is actually helping conservation of forests”. What Policies Can Help Students Affected by COVID-19? Examples – Bakelite, Melamine, Silicone, Epoxy. Ask your doubts related to NIOS or CBSE Board and share your knowledge with your friends and other users through Discussion Forum. It is used for non-stick coating on cook-wares. The coating on modern non- stick cookware and electric iron is of a) Terrycot. Question 14. It contributes sturdy structure to the plants. Polymerization in the simplest form can be described as a chemical process that results in the formation of polymers. These are reactive molecules and are usually linked to each other by covalent bonds. Some examples of their use are the packaging of tablets, many bottles, threads used for stitching wounds, syringes, doctors’ gloves and a number of medical instruments and so on. Bakelite items, particularly jewelry and radios, have become a popular collectible. After studying the NCERT Books, important Questions provide a proper revision of the chapter for exams. Why do people always prefer to choose plastic instead of using metals? MCQ Questions for Class 12 Chemistry with Answers were prepared based on the latest exam pattern. Which type of plastic is used for non-stick coating on cook-wares? 2) Reuse: Resources can be reused wherever possible. Plastics are poor conductors of heat and electricity. These are called thermosetting plastics. In the process it releases lots of poisonous fumes into the atmosphere causing air pollution. Would you like to help him? 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. The formation process of these two types of plastics also differs. 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. All organic compound comes to this category. 3) Melamine is used for making floor tiles and kitchenware. Synthetic fibre: There are some fibres which made from chemical substances, and they do not obtain from plant or animal sources. 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. Plastics are often made from petrochemicals like crude oil but can also be made from other materials. We should use of bags made of cotton or jute instead of plastic bags when we go for shopping. Most of the thermoplastics can be recycled. A material which gets decomposed through natural processes, such as action by bacteria, is called biodegradable. Classify the following into thermosetting and thermoplastics-combs, bakelite, melamine, toys. b) Silk. Give example to show that plastics are non-corrosive in nature. Fire proof plastic uniform worn by fire fighters has a coating of _____ to make it fire resistant. Such plastic which gets deformed easily on heating and can be bent easily are known as thermoplastics. Manufacturing Synthetic Fibres is Actually Helping Conservation of Forests, NCERT Solutions for Class 6 Social Science, NCERT Solutions for Class 7 Social Science, NCERT Solutions for Class 8 Social Science, NCERT Solutions for Class 9 Social Science, NCERT Solutions for Class 10 Social Science, NCERT Solutions for Class 11 Business Studies, NCERT Solutions for Class 11 Physical Education, NCERT Solutions for Class 12 Business Studies, NCERT Solutions for Class 12 Physical Education, CBSE Sample Papers for Class 10 Session 2020-2021, CBSE Sample Papers for Class 12 Session 2020-2021, Class 8 Science Chapter 4 Important Questions, Useful Tips To Score Good Marks On Programming Assignments, Top Essay Writing Service with Tons of Pros. Therefore, this fibre is referred as artificial silk or man-made fibre. How does plastic create problems for them? A material which is not easily decomposed by natural processes is termed as non-biodegradable. iii) Use bags made of cotton or jute or recycled paper, when you go for shopping. Such as plastic. Check the below NCERT MCQ Questions for Class 12 Chemistry Chapter 15 Polymers with Answers Pdf free download. iii)Synthetic fibres are less expensive and readily available in the market. We have provided Polymers Class 12 Chemistry MCQs Questions with Answers to help students understand the concept very well. Although rayon is obtained from a natural source, wood pulp, yet it is a man-made fibre. This fibre was called rayon or artificial silk. 8 Bakelite and Melamine are examples of. 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. Such fibre was obtained by chemical treatment of wood pulp. Answer. Can you guess why? It is used for making floor tiles, kitchenware and fabrics which resist fire. Class 8 Science Chapter 3 Important Questions of Synthetic Fibres and Fabric. It can be drawn into very fine fibres that can be woven like any other yarn. c) Melamine plastic. Which type of fibre is used in his sweater? Question 8. Acrylic blankets are cheap, light in weight, more durable and are available in variety of colours and designs. ii) Buy products without a little plastic packaging. Such as animals, trees, cotton, jute. “Paheli wants to know the uses of plastic in health-care industry”. So, a polymer is made of many repeating units. Thermosetting polymers are those which undergo permanent change on heating. Bakelite and Melamine are examples of a) Thermosetting plastics b) Silk c) Nylon d) Rayon. Justify the statement. Name some common articles made from fibres. All organic compound comes to this category. Will you help her? v) Synthetic fibres absorb very little water. Terylene is a popular polyester. How would you contribute towards the reducing the use of plastic materials? Polymers are generally formed by the addition of a network of structural units or small molecules called monomers. They can be easily washed at home. Each small unit is actually a chemical substance. Question 13. That is why electrical wires have plastic covering, and handles of screw drivers are made of plastic. Some important properties of bakelite are listed below. b) Rayon. The word ‘polymer’ comes from two Greek words; “poly” meaning “many” and “mer” meaning “part/unit”. After reading NCERT Books, you have just to go through these questions to prepare the entire chapter for exams. Class 8 Science Chapter 3 Important Questions are given below updated for new academic session 2020-21. These are used for manufacturing toys, combs and various types of containers. In the process of eating the food waste from dump of garbage – “they swallow materials like polythene bags and wrappers of food”. Can you suggest some methods to limit its consumption? Tutorial for Learning C Programming: Is It Possible to Learn the Programming Language Online. Why rayon is referred as “artificial silk” or “man-made fibre”? Question 12. Cellulose is made up of a large number of glucose units. Define the term synthetic fibre. These monomers add together to form a long chain to form a product with spe… Odd one out: choose the letter of the word that is not related from the other choices. “Despite being very useful, it is advised to restrict the use of plastic”. Towards the end of the nineteenth century, scientists were successful in obtaining a fibre having properties similar to that of silk. Download NCERT Books 2020-21 based on new CBSE Syllabus for session 2020-2021. Synthetic fibres are more durable and affordable which makes them more popular than natural fibres. Odd one out: choose the letter of the word that is not related from the other choices. These are prepared from a type of synthetic fibre, called acrylic. a) Thermosetting plastics. Although, polyester (Poly+ester) is actually made up of the repeating units of a chemical called an ester. Question 7. i) Avoid the use of plastics as far as possible. So, it is not advisable to dispose of the used plastic articles by burning. Explain the statement. It remains crisp and is easy to wash. It is used for making electrical switches, handles of various utensils, etc. Instead we can reuse them. a) Nylon. Question 25. Why are the chemicals in the laboratory stored in plastic containers ? They are not corroded easily. 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? The wool obtained from natural sources is quite expensive, whereas clothes made from acrylic are relatively cheap. For manufacturing synthetic fibres cutting of trees or killing of animals is not required and we can conserve our natural environment using synthetic fibres. Answer. Fabric made from this fibre does not get wrinkled easily. The list is endless if we start counting articles like slippers, furniture and decoration pieces, etc. It is further classified into, Homopolymers:Polymers formed by the polymerisation of a single monomeric species. Answer: (c) 10. Bakelite Structure. A synthetic fibre is also a chain of small units joined together. This is because of their light weight, lower price, good strength and easy handling. The 4 R principle is: 4R means Reduce, Reuse, Recycle and Recover. Esters are the chemicals which give fruits their smell. A common example of linear polymer A Bakelite B Melamine C Branched D Poly. They are available in a variety of colours. Such as plastic. Therefore, people always prefer to choose plastic instead of using metals. These cannot be re-melted. 2) Bakelite is a poor conductor of heat and electricity so, it is used for making electric switches and handles of the utensils. Sometimes people are very careless and throw the wrappers of chips, biscuits and other eatables on the road or in parks or picnic places. Some examples are natural gas or even corn, wheat, or rice. Melamine is a versatile material. Example : Bakelite, Melamine etc. They are also referred to as macromolecules. Bakelite is a thermosetting plastic, it cannot be molded again whereas Melamine, being a thermoplastic, can be molded any number of times adn reshaped. So, it is quite suitable for making dress material. Some examples of synthetic fibres are polyester, nylon and acrylic.