In the second part, the students will learn about plastics and its uses. 2) Polyester. 21. For example, polythene is made of many ethene monomer units. Column A Column B I. Nylon (i) Thermoplastic II. The most common source for the synthetic fibres is petroleum. Polystyrene without plasticizers is amorphous transparent and brittle a true or from PHYS 1015 at University of South Africa. It is very important for the students to get well versed with this NCERT Exemplar as it will aid them in gaining complete knowledge of the concepts included in Class 8 Science Chapter 3 Synthetic Fibres and Plastics. 2) It does not react chemically with other substances. Answer. 1) Nylon Crystallization affects optical, mechanical, thermal and chemical properties of … ... 4. b 5. a. iii, b. iv, c. v, d. i, e. ii. FALSE; Epoxy resin is a thermoplastic? Cotton is a natural polymer. But clay is not a polymer because polymers are made up of monomer units while clay is not made up of monomer units. A lady went to the market to buy a blanket. Which of these plastics can be repeatedly heated and moulded into any desired shape? List its important properties and uses. Bakelite is a thermosetting polymer i.e. It is used for making gaskets, pump packings, valves, seals etc. Why are plastic bottles commonly used to store chemicals in a chemistry laboratory? A bucket made of plastic does not rust like a bucket made of iron. branched. ? (c) inflammable Answer (a) nylon Wire made from nylon fibre is the strongest. The uses of rayon are: They can be easily washed at home. Rayon, a synthetic fibre, is also called artificial silk. Polyethylene, one of the most widely produced plastic in the world, is a thermoplastic polymer that has a variable crystalline structure. Which of the following represents the correct match for items in Column A with those in Column B. They do not occur naturally but are produced entirely in chemical plants or laboratories. (c) nylon Lata always prefers to buy things from the market that use fewer plastics in packaging why does Lata do this? Which of the following is a source of rayon? Define a thermosetting plastic and give examples. A plastic used for making crockery is melamine. Plastics are very useful materials. (a) rayon (ii) The synthetic fibres are also known as man-made fibres. 4. (a) polythene The uses of polyester are as follows: (a) rayon In option b) there is cotton which is from a plant source. Therefore, these type of clothes are not suitable in a kitchen. Which of these is a fibre derived from chemicals? Natural fibres are obtained by plants and animals and synthetic fibres are obtained by chemical processing. 2) Silk Bakelite is a thermosetting plastic and is used for making electrical switches, handles of various utensils, etc. Thermoplastic polymers can be repeatedly heated and moulded into any desired shape. Question 26. It is commonly used in cosmetics and personal care products, food packaging materials, and medical devices. The four properties of plastics are: Answer . All Living Science 2019 2020 Solutions for class Class 8 Science are prepared by experts and are 100% accurate. (b) cotton Indicate whether the following statements are True or False. 1) Nylon fibre is very strong and elastic. Highly filled thermoplastic circuit board (LuVo Board / Heger Board) Manufacturing process: extrusion . Two disadvantages of synthetic fibres are: This is followed by the regeneration of solidified synthetic fibres by passing them through spinnerets. Moreover, burning of plastics releases poisonous fumes, which causes air pollution. It is used to make thermocol. Which of the following is a thermoplastic? (i) A polymer is a chain of many small units joined together which are called ______. 6) Which of the following is commonly used in schools for vacuum forming? ... thermoplastic (c) polythene (d) none of these. Which of these is not a property of plastics? True. (b) polythene (c) teflon This is because of lightweight, low price, good strength and easy handling as compared to metals. Thermosetting plastics are bad conductors of heat and electricity. This weight indicates the strength of the fibre. That is why plastic buckets are used to store water and plastic glasses are used to drink water. But it is advised to avoid the use of plastic as far as possible. Hence it is advised to avoid the use of plastic as far as possible. 1. Which plastic material is used to make non-stick pans? Polythene pipes are used to transport liquids such as oil and water. Answer. 18. Rohit took with him some nylon ropes when he was going for rock climbing. (d) polyvinyl chloride. Moreover, mixing synthetic fibres with natural fibres enhances their properties, such as strength, elasticity and ease of washing and ironing. Answer: (A) Both assertion and reason are true and the reason is the correct explanation of assertion. What is its chemical name? Polyethylene is a member of the important family of polyolefin resins. False. Do you think rayon when burnt will stick to the body like other synthetic fibres? However, there is one major difference in their nature. (a) bakelite They cannot be decomposed by bacteria and so are non-biodegradable in nature. On heating, Thermoplastics get deformed and they can be easily bent. They cannot be decomposed by the microorganisms in the soil. SOLUTION Nylon is a generic designation for a family of synthetic polymers, based on aliphatic or semi-aromatic polyamides. 1) It is used to make curtains, table clothes, blankets, bed sheets, carpets etc. Examples of synthetic fibres: Plastic containers seem most convenient. Thermoplastics and thermosetting polymers are types of plastic that undergo different production processes and yield a variety of properties depending on the constituent materials and production method. 3. Inappropriate disposal of plastics is a serious problem. Why is it so? Plastics It is used to store food item, water, milk, pickles, dry food, etc. A different approach consists on employing thin layers of compact high temperature thermoplastics for the manufacturing of multilayer circuit boards. (a) bakelite On the other hand, clothes spun out of fibres made by a mixture of synthetic and natural fibres do not cause such problems. 10. Differentiate between thermoplastics and thermosetting plastics. 4) PVC is a thermoplastic. 1) Thermoplastics can be softened on heating again and again, therefore they can be moulded and reshaped. Recycling of plastic is more costly than its manufacturing. View NCERT Solutions for all chapters of Class 8, FREE Downloadable NCERT Solutions.Works without internet. Why? Question 15. Name one thermosetting plastic which is a good insulator and is used to make plugs and switches. b. Can you write the major difference between these two types of plastics? All questions and answers from the Living Science 2019 2020 Book of Class 8 Science Chapter 3 are provided here for you for free. Can you tell why he selected nylon ropes instead of ropes made of cotton or jute? It is the most widely used plastic in the world, being made into products ranging from clear food wrap and shopping bags to detergent bottles and fuel tanks. FALSE; PVC is a thermoplastic. Clay is a 'plastic' material. FALSE; HDPE is a tough plastic used for making toys. Oxygen gas is slightly soluble in water. (b) polystyrene When smaller units of a chemical substance are combined to form a large single unit, it is called a polymer. c. HIPS. 2) Plastic is suitable ... False. ? These fumes also cause cancer. 26. The common property of all plastics is that they are all made up of polymers. It is also mixed with a natural fibre like cotton and wool to make more variety of clothes. NCERT Exemplar for Class 8 science Synthetic Fibres and Plastics will bestow you with a variety of questions like synthetic fibres and plastics Class 8 MCQs, short answer questions and long answer questions. Nylon is a synthetic fibre which is very strong, even stronger than steel wire. What is the significance of the prefix 'poly' in 'polyester'? Polymers can crystallize upon cooling from melting, mechanical stretching or solvent evaporation. ) polyvinyl chloride ) is a 'plastic ' material because we can practise or promote proper disposal plastics. Of ethylene units.... See full answer below are: 1 ) synthetic fibres Melamine and formica thermosetting! 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