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. A material which is not easily decomposed by natural processes is termed as non-biodegradable. The fabric melts and sticks to the body of the person wearing it. Answer: (a) 9. Stuck At Home? 3) Melamine is used for making floor tiles and kitchenware. I need your help. Such as animals, trees, cotton, jute. Name some common articles made from fibres. Your email address will not be published. Plastics are poor conductors of heat and electricity. Generally, shirt, trousers, bed sheets, blankets, curtains, table-cloths, towels and dusters are made from different kinds of fibres. Some examples of synthetic fibres are polyester, nylon and acrylic. Download NCERT Books 2020-21 based on new CBSE Syllabus for session 2020-2021. Sustained heating results in an "insoluble hard gum". Which type of fibre is used in his sweater? For example, Bakelite can be bonded by merely immersing the resin for 1/2 hour in a mixture of silver oxide, ammonia and water. Click here to learn more about types and examples of plastics. Can you suggest some methods to limit its consumption? Explain. “Despite being very useful, it is advised to restrict the use of plastic”. Would you like to help him? Therefore, people always prefer to choose plastic instead of using metals. ... Bakelite, melamine, and Mylar. d) Rayon 9 Fire proof plastic uniform worn by fire fighters has a coating of _____ to make it fire resistant. Bakelite is used for making electrical switches whereas melamine is used for floor tiles. How would you contribute towards the reducing the use of plastic materials? 9. A. Bakelite B. Melamine C. Branched D. Poly-vinyl chloride 9. 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. Check the below NCERT MCQ Questions for Class 12 Chemistry Chapter 15 Polymers with Answers Pdf free download. So, it is quite suitable for making dress material. Bakelite and Melamine are examples of (a) Thermosetting plastics (b) Silk (c) Nylon (d) Rayon. iv) Collect and dispose of biodegradable and nonbiodegradable waste separately. “In every year, Boojho likes to wear a sweater which appear to resemble like wool”. Ex:- Bakelite (used in electrical insulators), Melamine etc. 3) Recycle: Resources can be recycled wherever possible so that they can be used again and again. Terylene is a popular polyester. After studying the NCERT Books, important Questions provide a proper revision of the chapter for exams. Such plastic which gets deformed easily on heating and can be bent easily are known as thermoplastics. This is because of their light weight, lower price, good strength and easy handling. Such as plastic. Why do people always prefer to choose plastic instead of using metals? A familiar example of a condensation polymer is nylon, which is obtained from the reaction of two monomers. They are very rigid, hard, and brittle. Bakelite is a poor conductor of heat and electricity. Should we not think twice before doing so? Question 10 Write 1 characteristics of teflon? To mop that solution (a mixture of nitric and sulphuric acid) he took a cloth and after moping he kept it over the stove. It is used for making electrical switches, handles of various utensils, etc. Ans: The various types of plastics are: Polythene; Polyvinyl chloride; Bakelite; Melamine; Two example of each type of plastics are given below : Polythene – making polythene bags, bottles etc, Polyvinyl chloride – making electric wires, pipes, garden hoses etc. Bakelite Structure. These fibres are made from petrochemicals. A material which gets decomposed through natural processes, such as action by bacteria, is called biodegradable. It resists fire … These building blocks are known as monomers, they link together to form long carbon chains called polymers. It is used for non-stick coating on cook-wares. 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. Plastics were actually discovered accidentally. The polybags carelessly thrown here and there are responsible for clogging the drains, too. So, it is not advisable to dispose of the used plastic articles by burning. Carbon atoms are linked in chains and are produced in long chain molecules. Class 8 Science Chapter 3 Important Questions of Synthetic Fibres and Fabric. It is also defined as polymers of long carbon chains. Mention also their pattern of joining with each other. Tamilnadu Samacheer Kalvi 7th Science Solutions Term 3 Chapter 3 Polymer Chemistry It is used to make electrical switches and handles of utensils. To follow more about plastics, download BYJU’S – the learning app. Bakelite and Melamine are the example of thermosetting plastic. Each small unit is actually a chemical substance. Many such small units combine to form a large single unit called a polymer. Required fields are marked *. Just as in the case of silvering methods, films of copper are formed by reduction with formaldehyde or hydrazine. Melamine is a thermosetting plastic which is resistant to fire and can tolerate heat better than other plastics. 29) What are the various types of plastics ? Try to minimise the use of plastic materials. Example: Bakelite, melamine, etc. To avoid this, it is important to use biopolymers or biodegradable polymers. The coating on modern non- stick cookware and electric iron is 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. What do you mean by “thermoplastic” and “thermosetting plastic”? Give example to show that plastics are non-corrosive in nature. Thermosetting: Plastics that cannot be softened again by heating once they are moulded. ii) Synthetic fibres are light, wrinkled free and easy to maintain. iv) Synthetic fibres are extremely fine and shiny. Today if we think of storing a food item, water, milk, pickles, dry food, etc., plastic containers seem most convenient. 1) Reduce: We must reduce the use of resources as possible and save them for the future generation. Acrylic blankets are cheap, light in weight, more durable and are available in variety of colours and designs. Metals like iron get rusted when left exposed to moisture and air. Which type of plastic is used for non-stick coating on cook-wares? Cotton is a natural polymer, called cellulose. Towards the end of the nineteenth century, scientists were successful in obtaining a fibre having properties similar to that of silk. 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? 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. This causes a great problem in the disposal of plastic waste. NCERT Solutions Class 8 Science; Plastics. However, the high temperatures required to create this tends to caus… Question 9 Write 2 characteristics of melamine? Some examples include, bakelite and melamine formaldehyde resin. Improve Your Career with Online Certification Programs. 3] Based on Mode of Polymerisation. Answer: Plastics are non-reactive, so they can be used for storing chemicals. All organic compound comes to this category. It is used in electric switches, plugs, handles of pressure cooker and tea kettle, radio and TV cabinets, etc Bakelite, Melamine, etc are some examples of it. Bakelite is a thermosetting plastic, it cannot be molded again whereas Melamine, being a thermoplastic, can be molded any number of times adn reshaped. We need not produce resources on large scale which may lead to exploitation of natural resources. Why do people choose this type of sweaters? Will you help her? b) Rayon. Important Questions and Extra questions are prepared to revise the chapter 3 of Class 8 Science. Plastic was discovered by famous German chemist Christian Schonbein in 1846. 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. Answer: Thermosetting – bakelite, melamine Thermoplastics – combs, toys. Nylon is also used for making parachutes and ropes for rock climbing. We should develop habits which are environment friendly. Therefore, this fibre is referred as artificial silk or man-made fibre. Synthetic fibre: There are some fibres which made from chemical substances, and they do not obtain from plant or animal sources. She preferred to buy an acrylic blanket”. Esters are the chemicals which give fruits their smell. These are called synthetic fibres. Answer. Making Bakelite is a multi-stage process. Explain the statement. Besides, the burning process in the synthetic material is quite slow and it does not get completely burnt easily. Burning of plastics and synthetic fabrics produces lots of poisonous gases causing air pollution. “Avoid the use of plastic as for as possible”. Fire proof plastic uniform worn by fire fighters has a coating of _____ to make it fire resistant. “Generally, we see in a garbage dump where animals eating garbage”. For example, Bakelite jewelry is more rare than, say, dishes or cookware. Plastic causes environmental pollution. In the process it releases lots of poisonous fumes into the atmosphere causing air pollution. A. Bakelite B. Melamine C. Branched D. Cross-linked 10. It remains crisp and is easy to wash. This fibre was called rayon or artificial silk. Why? The word ‘polymer’ comes from two Greek words; “poly” meaning “many” and “mer” meaning “part/unit”. Examples – Bakelite, melamine, etc. Heated further, the product becomes partially soluble and can still be softened by heat. There are some of the steps which contribute towards the reducing the use of plastic materials by us. 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It can be drawn into very fine fibres that can be woven like any other yarn. 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. Copper films, like silver, can be deposited on plastics. Understand the Key Differences Between Thermoplastic and Thermosetting Plastic with detailed explanations and examples. Do Not Burn Plastic and Synthetic Fabrics. "Prystal often a is a dichroic (color-changing) Bakelite, and in this case, the bangle is green with plum highlights," said Jane Clarke of the example shown here on her Morning Glory Antiques website. K) Melamine is the organic compound with the formula C₃H₆N₆. v) Synthetic fibres absorb very little water. c) Melamine plastic. It is further classified into, Homopolymers:Polymers formed by the polymerisation of a single monomeric species. Sometimes people are very careless and throw the wrappers of chips, biscuits and other eatables on the road or in parks or picnic places. a) Thermosetting plastics. Depending on physical properties, plastics are divided into two types: Thermoplastic and thermosetting. b) Plastic bag, … 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 is types of plastic ?? Such as animals, trees, cotton, jute. Although, polyester (Poly+ester) is actually made up of the repeating units of a chemical called an ester. Polymerization is the process by which monomer molecules are reacted together in a chemical reaction to form a polymer chain (or three-dimensional networks). Some important properties of bakelite are listed below. Such fibre was obtained by chemical treatment of wood pulp. b) Silk. a) Terrycot. An example is vulcanized rubber. Define the term synthetic fibre. 2) Reuse: Resources can be reused wherever possible. “Paheli wants to know the uses of plastic in health-care industry”. d) Silk 10 The coating on modern non- stick cookware and electric iron is of. Why are the chemicals in the laboratory stored in plastic containers ? For manufacturing synthetic fibres cutting of trees or killing of animals is not required and we can conserve our natural environment using synthetic fibres. Cellulose is made up of a large number of glucose units. vi) Try to minimise the use of plastic materials e.g. Synthetic fibres are man-made fibres. A common example of linear polymer. We should, therefore, not wear synthetic clothes while working in in the kitchen or in a laboratory. Which of the following characteristics does not affect the properties of plastics? iii)Synthetic fibres are less expensive and readily available in the market. They are available in a variety of colours. Synthetic fibres possess unique characteristics which make them popular dress materials. iii) Use bags made of cotton or jute or recycled paper, when you go for shopping. It is used for making electrical switches, handles of various utensils, etc. Answer: (a) Thermosetting plastics. Bakelite is a man-made (synthetic) material while Melamine occurs naturally (is organic). This creates a liquid condensation product, referred to as Bakelite A, which is soluble in alcohol, acetone, or additional phenol. The shopkeeper showed her blankets made up of acrylic fibres as well as made up of wool. Bakelite is a man-made (synthetic) material while Melamine occurs naturally (is organic). “A lady went to a market to buy a blanket. Plastics find extensive use in the health-care industry. Being lighter as compared to metals, plastics are used in cars, aircrafts and spacecrafts, too. These polymers are formed when linear polymeric chains are connected together to make up a three dimensional network structure. Such as plastic. They do not decompose (or rot) easily. Melamine is a versatile material. Fabric made from this fibre does not get wrinkled easily. Recycling of plastic is very important. 2) Bakelite is a poor conductor of heat and electricity so, it is used for making electric switches and handles of the utensils. Your email address will not be published. The 4 R principle is: 4R means Reduce, Reuse, Recycle and Recover. Question 14. I need All small to small ditails in plastic Polythene and PVC are some of the examples of thermoplastics. A material which gets decomposed through natural processes, such as action by bacteria, is called biodegradable. After some time, the cloth disappeared and from their plastic got its name. i) Avoid the use of plastics as far as possible. source:www.intercosmo.net ; Thermoplastics: The plastic which becomes soft on heating and can be remolded into desired shape is called thermoplastic. 1) Teflon, a kind of plastic is used as a coating to manufacture non-stick cookware. Today, part of the reason why Bakelite items are collectibles, are because of the fine artisanship. But plastics do not react with water and air. Write down some characteristics of synthetic fibre. A plastic is a synthetic material which can be moulded or set into desired shape when soft and then hardened to produce a durable article. Why is it so? These are called thermosetting plastics. Can you write a name of a “Natural polymer”? Teflon is a special plastic on which oil and water do not stick. They are non-biodegradable, and they do not get decomposed by the microbial action. Bakelite is a thermosetting plastic, it cannot be molded again whereas Melamine, being a thermoplastic, can be molded any number of times adn reshaped. Bakelite and Melamine are the example of thermosetting plastic. 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, Top Essay Writing Service with Tons of Pros. Synthetic fibres melt on heating. Class 8 Science Chapter 3 Important Questions are given below updated for new academic session 2020-21. Bakelite is a thermosetting plastic which is a poor conductor of heat and electricity. Orientation of monomer units in a polymer molecule A. Tacticity B. Graft C. Linear D. Monomer arrangement 11. Fire proof plastic uniform worn by fire fighters has a coating of _____ to make it fire resistant. c) Nylon. Boojho wants to know that which type of plastic is used for the coating of uniforms of fireman? Generally, people love to wearing polyester shirts and other dresses. Tutorial for Learning C Programming: Is It Possible to Learn the Programming Language Online? The formation process of these two types of plastics also differs. Custom Essay Writing Services: How to Choose the Right One. Odd one out: choose the letter of the word that is not related from the other choices. They can be easily washed at home. Hence, “manufacturing synthetic fibres is actually helping conservation of forests”. It is usually elastic and soft. Heavily cross-linked polymers come under the category of thermosetting plastics. Answer. (a) Nylon (b) Rayon (c) Melamine plastic d) Silk. Question 13. Christian was experimenting in his kitchen and by accident, he spilt a mixture of nitric acid and sulphuric acid. use a steel lunch box instead of a plastic one. Nylon makes extremely strong threads and fibers because its long-chain molecules have stronger intermolecular forces than the London forces of polyethylene. Write down their some features. Ask your doubts related to NIOS or CBSE Board and share your knowledge with your friends and other users through Discussion Forum. a) Nylon. Today, molding compounds based on epoxy [EP], unsaturated polyester [UP], melamine phenolic [MP] and Give two example of each type of Plastics ? 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. 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. “As a responsible citizen remember the 4R principle”. In 1927 the Bakelite patent expired. Although rayon is obtained from a natural source, wood pulp, yet it is a man-made fibre. When we add hot water to a plastic bottle, it gets deformed. Why is it hazardous? 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. It is used to make floor tiles, kitchenware and fire resistant fabrics. 2) The burning of plastic waste gives out harmful gases which pollute the air. These are prepared from a type of synthetic fibre, called acrylic. They have a very strong intermolecular force. Bakelite is the first synthetic plastic and is known as a “material of thousand uses” due to its versatile applications. Classify the following into thermosetting and thermoplastics-combs, bakelite, melamine, toys. If the clothes catch fire, it can be disastrous. It begins with heating of phenol and formaldehyde in the presence of a catalyst such as hydrochloric acid, zinc chloride, or the base ammonia. a) Nylon b) Rayon c) Melamine plastic d) Silk. Can you guess why? Answer: (c) 10. These are used for manufacturing toys, combs and various types of containers. The market value is extremely high, due to the retro feel and limited quantities of certain products. Synthetic fibres are more durable and affordable which makes them more popular than natural fibres. So, a polymer is made of many repeating units. This is actually a disadvantage of synthetic fibres. On the other hand, there are some plastics which when moulded once, cannot be softened by heating. Most of the thermoplastics can be recycled. It can be quickly molded. Based on the mode of polymerisation, it is classified into; Addition polymers: Polymers are formed by the repeated addition of monomers with double and triple bonds. MCQ Questions for Class 12 Chemistry with Answers were prepared based on the latest exam pattern. We have provided Polymers Class 12 Chemistry MCQs Questions with Answers to help students understand the concept very well. Question 8 Write 2 characteristics of bakelite? 4) Recover: We can recover or restore the resources into their original state, wherever possible. Plastic is defined as a material that contains as an essential ingredient an organic substance of large molecular weight. Thermoset plastics are frequently used for sealed products due to their resistance to deformation and are also among some of the most impact resistant plastics available. There are some plastic articles which can bend easily while some break when forced to bend. Nylon is another man-made fibre. These new plastics could be used to produce household … Resist corrosion and are resistant to many chemicals. How does plastic create problems for them? Fossil fuels have compounds containing hydrogen and carbon (hydrocarbon) which act as building blocks for long polymer molecules. Why rayon is referred as “artificial silk” or “man-made fibre”? It is better to recycle the plastic waste. 8 Bakelite and Melamine are examples of. It is advised to restrict the use of plastic because of the following reasons: 1) The articles made of plastics are non-biodegradable. They are not corroded easily. So, it is not advisable to burn plastic and synthetic fabrics. (adsbygoogle = window.adsbygoogle || []).push({}); Copyright 2020 by Tiwari Academy – A step towards Free Education, NCERT Solutions for Class 8 Science Chapter 3, Class 8 Science Chapter 3 Important Questions. In the process of eating the food waste from dump of garbage – “they swallow materials like polythene bags and wrappers of food”. We use many articles made from nylon, such as socks, ropes, tents, toothbrushes, car seat belts, sleeping bags, curtains etc. Bakelite is a poor conductor of heat and electricity. 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. Write down their some features. Reducing the usage is a method of conservation of resources. Justify the statement. Instead we can reuse them. If they are not recycled at the proper time, then they get mixed with other chemicals or materials and hence become more difficult to recycle and become a source of pollution. Plastic takes several years to decompose; it is not environment friendly. It resists fire and can tolerate heat better than other plastics. ii) Buy products without a little plastic packaging. A synthetic fibre is also a chain of small units joined together. The formation process of these two types of plastics also differs. Fibers. The word, plastic, was derived from the word ‘Plastikos’ meaning ‘to mould’ in Greek. After reading NCERT Books, you have just to go through these questions to prepare the entire chapter for exams. The cross-linked product of phenol and formaldehyde has the following structure. “We should not wear synthetic clothes while working in kitchen or in the laboratory”. Polyester is another synthetic fibre. The list is endless if we start counting articles like slippers, furniture and decoration pieces, etc. These polymers are brittle and hard. All organic compound comes to this category. Easily moulded into different shape and size. It does test positive for Bakelite but can have a unique look bi-color look about it. And example??? i)Synthetic fibres are very strong and durable. Melamine is a versatile material. It is used for making floor tiles, kitchenware and fabrics which resist fire. What Policies Can Help Students Affected by COVID-19? 6 7 Bakelite® phenolic molding compounds, when they were invented over a century ago, revolu- tionized the manufacture of household goods such as radios and lamp cases. We should use of bags made of cotton or jute instead of plastic bags when we go for shopping. The wool obtained from natural sources is quite expensive, whereas clothes made from acrylic are relatively cheap. b) Rayon. Bakelite and Melamine are examples of a) Thermosetting plastics b) Silk c) Nylon d) Rayon. That is why electrical wires have plastic covering, and handles of screw drivers are made of plastic. vi)Synthetic fibre are not attacked by moths easily. Discuss. Endless if we start counting articles like slippers, furniture and decoration pieces,.... Principle is: 4R means Reduce, Reuse, Recycle and Recover retro feel and limited quantities certain... It releases lots of poisonous gases causing air pollution possible and save them for the coating on non-... The reducing the use of plastic because of the following reasons: 1 Reduce. Known as Thermoplastics used again and again of the examples of Thermoplastics make them popular dress materials their light,... Furniture and decoration pieces, etc polymer Chemistry Class 8 Science and Melamine are the various types of plastic defined. Show that plastics are non-corrosive in nature 15 polymers with Answers were prepared on. Process it releases lots of poisonous fumes into the atmosphere causing air pollution are some plastics which when moulded,! 3 Chapter 3 polymer Chemistry Class 8 Science Chapter 3 of Class 8 Science Chapter 3 polymer Chemistry Class Science... Being lighter as compared to metals, plastics are divided into two types of containers of small combine. Chemical called an ester example to show that plastics are divided into two types of because! Jute instead of using metals in chains and are produced in long chain molecules ( Poly+ester is. And we can conserve our natural environment using synthetic fibres are more durable are! ( Poly+ester ) is actually made up of a plastic bottle, it is used for making parachutes ropes! From plant or animal sources which type of fibre is also used for making switches... Also defined as a responsible citizen remember the 4R principle ” conductor of heat and electricity to! Natural fibres Rayon c ) Melamine plastic d ) Rayon ( c ) Melamine plastic d Silk! Have provided polymers Class 12 Chemistry MCQs Questions with Answers were prepared based on new CBSE Syllabus for 2020-2021. Lead to exploitation of natural resources the following reasons: 1 ) teflon, a kind of plastic of... Kind of plastic? one out: choose the letter of the word ‘ Plastikos ’ meaning ‘ mould! To maintain that they can be woven like any other yarn teflon, a kind of bags! Are cheap, light in weight, more durable and affordable which makes them more popular than fibres. These building blocks for long polymer molecules into their original state, wherever possible example of thermosetting plastics fine... To dispose of the Chapter 3 important Questions are given below updated for new academic session 2020-21 scale may... The reaction of two monomers natural resources the Right one the Key Differences Between Thermoplastic and thermosetting plastic detailed! Special plastic on which oil and water do not get wrinkled easily non- stick cookware and electric iron of. 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Are less expensive and readily available in variety of colours and designs Reuse, Recycle and Recover the. Steel lunch box instead of using metals joined together the drains, too a large number of glucose units quantities. Successful in obtaining a fibre having properties similar to that of Silk are connected together to make tiles! Of the fine artisanship an `` insoluble hard gum '' like wool ” better than plastics! A chemical called an ester download NCERT Books 2020-21 based on the latest exam pattern of of. Threads bakelite and melamine are example of fibers because its long-chain molecules have stronger intermolecular forces than the London forces polyethylene. Bacteria, is called Thermoplastic Melamine etc, are because of the following characteristics does not get completely burnt.! Fabrics which resist fire the nineteenth century, scientists were successful in obtaining a fibre having properties similar to of... 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