A common example of linear polymer A Bakelite B Melamine C Branched D Poly. They do not decompose (or rot) easily. iii) Use bags made of cotton or jute or recycled paper, when you go for shopping. Synthetic fibres possess unique characteristics which make them popular dress materials. So, it is not advisable to burn plastic and synthetic fabrics. iv) Collect and dispose of biodegradable and nonbiodegradable waste separately. 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. Polythene and PVC are some of the examples of thermoplastics. The first human-made plastics were actually made using cellulose from plants. Which type of fibre is used in his sweater? 3) Melamine is used for making floor tiles and kitchenware. Therefore, this fibre is referred as artificial silk or man-made fibre. Write down their some features. Metals like iron get rusted when left exposed to moisture and air. Give example to show that plastics are non-corrosive in nature. So, it is not advisable to dispose of the used plastic articles by burning. Bakelite Structure. These are used for manufacturing toys, combs and various types of containers. Why do people always prefer to choose plastic instead of using metals? See more. The coating on modern non- stick cookware and electric iron is of Orientation of monomer units in a polymer molecule A. Tacticity B. Graft C. Linear D. Monomer arrangement 11. Do Not Burn Plastic and Synthetic Fabrics. Teflon is a special plastic on which oil and water do not stick. Being lighter as compared to metals, plastics are used in cars, aircrafts and spacecrafts, too. Although, polyester (Poly+ester) is actually made up of the repeating units of a chemical called an ester. 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. vi) Try to minimise the use of plastic materials e.g. Such fibre was obtained by chemical treatment of wood pulp. use a steel lunch box instead of a plastic one. We have provided Polymers Class 12 Chemistry MCQs Questions with Answers to help students understand the concept very well. Plastics are poor conductors of heat and electricity. Discuss. 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? Cotton is a natural polymer, called cellulose. Explain the statement. 2) Bakelite is a poor conductor of heat and electricity so, it is used for making electric switches and handles of the utensils. vi)Synthetic fibre are not attacked by moths easily. It is used for making floor tiles, kitchenware and fabrics which resist fire. Odd one out: choose the letter of the word that is not related from the other choices. The shopkeeper showed her blankets made up of acrylic fibres as well as made up of wool. Check the below NCERT MCQ Questions for Class 12 Chemistry Chapter 15 Polymers with Answers Pdf free download. Question 13. Generally, people love to wearing polyester shirts and other dresses. 1) Reduce: We must reduce the use of resources as possible and save them for the future generation. Class 8 Science Chapter 3 Important Questions are given below updated for new academic session 2020-21. After reading NCERT Books, you have just to go through these questions to prepare the entire chapter for exams. We should develop habits which are environment friendly. Today if we think of storing a food item, water, milk, pickles, dry food, etc., plastic containers seem most convenient. Can you write a name of a “Natural polymer”? a) Nylon b) Rayon c) Melamine plastic d) Silk. (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. ii) Synthetic fibres are light, wrinkled free and easy to maintain. Question 7. For example, Bakelite, and Melamine formaldehyde. Some important properties of bakelite are listed below. A synthetic fibre is also a chain of small units joined together. 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. These are called thermosetting plastics. Besides, the burning process in the synthetic material is quite slow and it does not get completely burnt easily. Why is it so? iii)Synthetic fibres are less expensive and readily available in the market. 2) Reuse: Resources can be reused wherever possible. 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. c) Melamine plastic. a) Thermosetting plastics. Answer: (a) 9. Examples – Bakelite, Melamine, Silicone, Epoxy. They are available in a variety of colours. Melamine is a versatile material. Example : Bakelite, Melamine etc. Bakelite and Melamine are the example of thermosetting plastic. Which type of plastic is used for non-stick coating on cook-wares? 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. It is used for making electrical switches, handles of various utensils, etc. These are called synthetic fibres. i) Avoid the use of plastics as far as possible. The formation process of these two types of plastics also differs. b) Silk. Boojho wants to know that which type of plastic is used for the coating of uniforms of fireman? The list is endless if we start counting articles like slippers, furniture and decoration pieces, etc. How is plastic made? There are some plastic articles which can bend easily while some break when forced to bend. What Policies Can Help Students Affected by COVID-19? “Avoid the use of plastic as for as possible”. Why do people always prefer to choose plastic instead of using metals? Plastic causes environmental pollution. a) Nylon. iv) Synthetic fibres are extremely fine and shiny. Odd one out: choose the letter of the word that is not related from the other choices. Synthetic fibres are more durable and affordable which makes them more popular than natural fibres. Define the term synthetic fibre. Polymers are generally formed by the addition of a network of structural units or small molecules called monomers. They are not corroded easily. “Paheli wants to know the uses of plastic in health-care industry”. Important Questions and Extra questions are prepared to revise the chapter 3 of Class 8 Science. Instead we can reuse them. It is further classified into, Homopolymers:Polymers formed by the polymerisation of a single monomeric species. Some examples of synthetic fibres are polyester, nylon and acrylic. What do you mean by “thermoplastic” and “thermosetting plastic”? We should use of bags made of cotton or jute instead of plastic bags when we go for shopping. This is actually a disadvantage of synthetic fibres. Answer. There are some of the steps which contribute towards the reducing the use of plastic materials by us. 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. b) Rayon. On the other hand, there are some plastics which when moulded once, cannot be softened by heating. Bakelite and Melamine are examples of a) Thermosetting plastics b) Silk c) Nylon d) Rayon. “In every year, Boojho likes to wear a sweater which appear to resemble like wool”. After studying the NCERT Books, important Questions provide a proper revision of the chapter for exams. 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. It remains crisp and is easy to wash. Write down some characteristics of synthetic fibre. “As a responsible citizen remember the 4R principle”. Nylon is another man-made fibre. Burning of plastics and synthetic fabrics produces lots of poisonous gases causing air pollution. Addition polymers: Polymers are formed by the repeated addition of monomers with double and triple bonds. These are prepared from a type of synthetic fibre, called acrylic. 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