202110241-TRIUMPH-STUDENT-WORKBOOK-PHYSICAL_SCIENCE-G08-PART1

Long Answer Type Questions 9. Answer the following questions in 6-8 sentences. (i) [(Session 2.4)] Analyze and complete the table with correct answers. S.No. Situation Ways to Reduce Friction 1 To reduce friction between machinery parts 2 To reduce the friction between cycle chain and the cycle 3 To reduce fluid friction in Aeroplane 4 To reduce the friction on carrom board CHAPTER 2. FRICTION 49

AS5-Communication through drawing and model making Short Answer Type Questions 10. Answer the following questions in 3-4 sentences. (i) [(Session 2.1)] Write the different force acting on the box. Long Answer Type Questions 11. Answer the following question. (i) [(Session 2.2)] Rahul is sliding down an inclined plane. Draw a free body diagram to show various forces acting on a body sliding on an inclined plane. CHAPTER 2. FRICTION 50

CHAPTER 2. FRICTION 51

AS6-Appreciation and aesthetic sense, Values Short Answer Type Questions 12. Answer the following questions in 3-4 sentences. (i) [(Session 2.4)] Birds and fishes move in fluids all the time. How do you appreciate the way their body is designed to overcome fluid friction? CHAPTER 2. FRICTION 52

AS7-Application to daily life, concern to bio diversity Long Answer Type Questions 13. Answer the following questions in 6-8 sentences. (i) [(Session 2.3)] Describe two examples from your daily life to demonstrate the follow- ing: a) Friction is desirable. b) Friction is undesirable. CHAPTER 2. FRICTION 53

Objective Questions AS1-Conceptual Understanding 14. Choose the correct answer. (i) Friction is proportional to the _____________________. (A) normal force (B) limiting force (C)applied force (D) none (ii) If friction is not exerted, the moving objects will never . (A) stop or move (B) stop (C) move (D)none of the above (iii) In science, the common name for gases and liquids is _________. (A) liquid (B) gases (C) fluid (D) none (iv) When one body rolls over the surface of another body, the friction offered is called (A) rolling friction (B) static friction (C)sliding friction (D) none (v) The direction of motion of an object depends on the direction of the acting on it. (A) gravitational force (B) electrostatic force (C)net force (D)magnetic force (vi) Which of the following force acting on the body is equivalent to the weight of the body? (A) Gravitational force (B) Electrostatic force (C)Net force (D)Magnetic force CHAPTER 2. FRICTION 54

(vii) ____________ friction comes into play when the surface of one object moves relative to the surface of another object. A) Static B) Rolling C) Sliding D) Fluid (viii) Force acting against relative motion of surface is called . (A) gravitational force (B) electrostatic force (C) friction (D)magnetic force (ix) Frictional force always depends on . (A) nature of the surface of contact (B) chemical composition of the objects (C)weight of the object (D)physical appearance of the surface of contact AS2-Asking questions and making hypothesis 15. Choose the correct answer. (i) Which of the following are effects of friction in moving parts? (A) Overheating and wearing out (B) Overheating and smoothening (C)Overheating and greasing (D)Overheating and protecting (ii) Which of the statements given below is correct? (A) Friction increases the temperature of the surface (B) Friction decreases the temperature of the surface (C)Friction maintains the temperature of the surface (D)Friction and temperature of the surface have nothing to do with each other CHAPTER 2. FRICTION 55

AS3-Experimentation and field investigation 16. Choose the correct answer. (i) The force acting perpendicularly on a unit area of surface is called . (A) thrust (B) pressure (C)normal force (D) tension AS4-Information skills and projects 17. Choose the correct answer. (i) “Friction can never be reduced to zero.” The given statement is (A) incorrect (B) correct (C)correct but not applicable always (D)none of these AS7-Application to daily life, concern to bio diversity 18. Choose the correct answer. (i) Identify the case in which rolling friction is acting. (A) A wooden box moving on an inclined plane (B) A rock just starts to move when pushed (C)A bowling ball moving in the lane (D)A book kept on the table CHAPTER 2. FRICTION 56

3. SYNTHETIC FIBRES AND PLASTICS SESSION 1 SYNTHETIC FIBRES AND THEIR USES 1.1 Mind Map 1. Types of fibres SESSION 1. SYNTHETIC FIBRES AND THEIR USES 57

Types of synthetic fibers, preparation, properties and uses SESSION 1. SYNTHETIC FIBRES AND THEIR USES 58

SESSION 1. SYNTHETIC FIBRES AND THEIR USES 59

SESSION 1. SYNTHETIC FIBRES AND THEIR USES 60

SESSION 1. SYNTHETIC FIBRES AND THEIR USES 61

2. Advantages and disadvantages of synthetic fibres : SESSION 1. SYNTHETIC FIBRES AND THEIR USES 62

2. Advantages and disadvantages of synthetic fibres 1.2 Terminology i. Synthetic/Artificial fibres – Fibres which are made by the raw materials obtained from petroleum are called synthetic or artificial fibres. ii. Monomers – Small units which are joined together to form a large unit polymer are called as monomers. iii. Blending – Any synthetic fibre can be combined with two or more other fibres. This is called blending. iv. Cellulose – Cellulose is a natural polymer obtained from plants which is made up of glucose monomers. v. Natural fibres – Fibres which are obtained from plant or animal sources are called natural fibres. vi. Polyamide – Polyamides are polymers which occur both naturally and artificially. Examples of natural polyamides are wool, silk, etc. vii. Silkworm – Silk is obtained naturally from silkworm. SESSION 1. SYNTHETIC FIBRES AND THEIR USES 63

viii. Spinneret – An organ or part by means of which a spider, insect, or larva spins a silky thread for its web or cocoon. ix. Terrycot – Terrycot is a synthetic fibre made by blending cotton and terylene fibres. x. Terylene – Terylene is a popular polyester which can be drawn into very fine fabric fibres. xi. Terrywool – Terrywool is a synthetic fibre made by blending terylene and wool. xii. PET – PET stands for Polyethylene Terephthalate. It’s a plastic resin and the most common type of polyester. 1.3 Key Concepts i. We use natural or synthetic type of fabrics. ii. Synthetic fibres are made up of very large units called polymers. iii. Polyesters are the most commonly used synthetic fibre. iv. Petrochemicals are used in manufacturing synthetic fibres. v. Nylon is made artificially by using coal, water and air. vi. Rayon is an artificial silk prepared from cellulose fibre. vii. Acrylic replaces woollen clothing because of its low price. Acrylic is prepared by using coal, air, water, oil and limestone. viii. Synthetic fibres are blended with natural fibres to improve their quality. 1.4 Reflection on Concepts Q1. [AS1] Why are some fibres called synthetic fibres? [Refer to TB page 49 Q1] A. Some fibres make use of chemical sources in their process of production. They do not use plant or animal sources as their raw material. Such fibres are called synthetic or artificial fibres. Q2. [AS1] List out the objects made up of acrylic. [Refer to TB page 49 Q2] A. Fleece, socks, sportswear and sweaters. It is also used in craft yarns, upholstery fabric, carpets, luggage awnings and vehicle covers. SESSION 1. SYNTHETIC FIBRES AND THEIR USES 64

1.5 Application of Concepts Q1. [AS7] How synthetic fibres changed our everyday life? [Refer to TB page 49 Q1] A. Synthetic fibres have reduced the cost of clothes and have revolutionised how clothes can be manufactured and the way we live also. We are now able to travel in the rain, thanks to water resistant clothes. They absorb less water and dry at a faster rate. They are durable, less expensive, readily available, affordable and are easy for maintenance. Q2. [AS7] Rani wants to buy clothes for her parents for winter wear. What type of clothes would you suggest? Specify reasons. [Refer to TB page 50 Q6] A. Woollen clothes. It protects from cold and provides warmth to body. 1.6 Higher Order Thinking Skills Q1. [AS2] What made the human beings to search for the alternative to natural fibre? [Refer to TB page 50 Q1] A. Difficulty in maintenance and cost of fabrics. Q2. [AS6] Introduction of synthetic fibres in the textile industry brought revolutionary change across the world in the dressing patterns irrespective of culture and customs. How do you appreciate this? [Refer to TB page 50 Q4] A. The introduction of synthetic fibres across the world has been a major cause in bridging gaps in cultures between the East and the West. The styles and fashions of each place have travelled over the world irrespective of where they came from and greatly influenced the culture of where they went. For e.g. Denim jeans have spread from the West to India and have played a major part in ‘westernisation’. 1.7 Suggested Projects Q1. [AS4] Prepare a table of various synthetic fibres which are used to make household articles from them? (Pg 51; TB Q 1) SESSION 1. SYNTHETIC FIBRES AND THEIR USES 65

A. S.No. Name of Type of Source Household the fibre fibre material article 1 Nylon Synthetic Coal, water, Ropes, air clothes, fishing nets, car seat belts, sleeping bags, curtains, sarees, ropes etc. 2 Rayon Synthetic Cotton pulp, Blankets, bed chemicals sheets, carpets, sanitary products, diapers, bandages and lints for dressing wounds etc. 3 Acrylic Synthetic Coal, water, Sweaters, craft air, oil and yarns, limestone carpets,vehicle covers etc. 4 Polyester Synthetic Dicarboxylic Dresses, acid, utensils etc. dihydric alcohol Objective Questions .(Pg 50;TB Q 1) (1) Rayon is prepared by (B) Oxygen (D) Cellulose (A) Coal (C) Fibre Correct Answer: D SESSION 1. SYNTHETIC FIBRES AND THEIR USES 66

(2) Labels on clothes are used because .(Pg 50; TB Q 2) (A) Required by laws (B) To identify fabric content (C)Both A and B (D)They do not decompose Correct Answer: B (3) Which is a Natural fibre among the following?(Pg 51; TB Q 5) (A) Rayon (B) Nylon (C) Polyester (D) Silk Correct Answer: D SESSION 1. SYNTHETIC FIBRES AND THEIR USES 67

SESSION 2 PLASTICS - TYPES AND EFFECT ON ENVIRONMENT 2.1 Mind Map 1. Types of plastics 2. Advantages and disadvantages of plastic : 68 SESSION 2. PLASTICS - TYPES AND EFFECT ON ENVIRONMENT

2. Advantages and disadvantages of plastic SESSION 2. PLASTICS - TYPES AND EFFECT ON ENVIRONMENT 69

3. Principles of waste management 2.2 Terminology i. Biodegradable – A material which is easily decomposed by natural process is called bio–degradable. ii. Non–biodegradable – A material which is not decomposed by natural processes is called non–biodegradable. iii. Recycling – Recycling is a process to convert waste materials into reusable material. SESSION 2. PLASTICS - TYPES AND EFFECT ON ENVIRONMENT 70

iv. Reusing – Articles made of plastics may be used again and again for their optimum utilization. This process is called reusing. v. Thermoplastics – Thermoplastic is a type of plastic which softens when heated and hardens when cooled. vi. Thermosetting plastics – Thermosetting plastics are simply plastics when moulded into a shape and allowed to cool down will remain in moulded form and will not change their shape. vii. Universal recycling symbol – The three chasing arrows are a universal recycling sym- bol, internationally–recognized to designate that a material is either recyclable, or contains recycled materials. 2.3 Key Concepts i. Plastic is a polymer available in different shapes and sizes. ii. Thermosetting plastics and thermoplastics are widely used in our day to day life. iii. Bakelite is an early form of brittle plastic made from formaldehyde and phenol used chiefly for electrical equipment. iv. Melamine is a very durable thermosetting plastic. v. Polyamides are made with monomers hexamethylene diamine and adipic acid. vi. Polythene or polyethene is a polymer made up of monomers of ethane. vii. Plastics lead to environmental problems. viii. Plastics take many years for decomposition. ix. Reduce the excessive use of plastics to reduce pollution. x. Universal recycling symbol is an internationally recognized symbol used to designate recyclable materials. 2.4 Reflection on Concepts Q1. [AS1] Give reasons. “Why are plastic containers are used as storage devices?” [Refer to TB page 49 Q5] A. The substance used as storage devices shouldn’t react with the substance that is stored in it. Hence plastic containers are used as storage devices. For example, it is common to find a 1.5 litre soft drink in plastic bottles. Carbonated water is slightly acidic and hence non–reactive substances such as plastic are used to store it. Q2. [AS1] What are thermosetting plastics. Give two examples. [Refer to TB page 49 Q4] A. There are some plastics which once molded can’t be softened by heating. They are called thermosetting plastics. SESSION 2. PLASTICS - TYPES AND EFFECT ON ENVIRONMENT 71

or Thermosetting plastics are simply plastics when moulded into a shape and allowed to cool down will remain in moulded form and will not change their shape. Bakelite and melamine are examples of thermosetting plastics. Q3. [AS5] Draw and explain the diagram of Universal Recycling symbol. [Refer to TB page 49 Q3] A. The universal recycling symbol is an internationally recognized symbol used to desig- nate recyclable materials. It is composed of three mutually chasing arrows that represent a Mo¨ bius strip (a single–sided looped surface). 2.5 Application of Concepts Q1. [AS1] If we make electric switches with thermo plastics. what would happen? [Refer to TB page 49 Q2] A. They would melt if there is any heat generated in the switch, causing a fire. Q2. [AS1] Where do we use the process of recycling? How is it useful? Give examples. [Refer to TB page 50 Q5] A. Paper, steel, and glass are all items that can be reused by recycling. The newspapers we get are the product of recycled paper. Recycling helps the environment by reducing waste. We find a lot of shops that take in old steel utensils, old newspapers, and old plastic products – all of these materials are then recycled. Q3. [AS7] What could be the consequences? If plastics are not properly disposed? [Refer to TB page 49 Q3] SESSION 2. PLASTICS - TYPES AND EFFECT ON ENVIRONMENT 72

A. As plastic is non–biodegradable it can cause a variety of problems: 1. If it is burnt it emits harmful gases. 2. Plastic wastes can block the drainage canals, causing environmental pollution. 3. The addition of plastics makes the soil less fertile as it won’t allow plants to grow well. 4. Eating of plastics has caused many adverse effects on cattle. Q4. [AS6] Is there any such effort for solid waste management taking place in your village / Town? How do you appreciate 4R principle? [Refer to TB page 50 Q4] A. Supreme Court gave a judgment on ways and means of solid waste management and gave order to implement this in all the cities of India by 2003.The objective of rural solid waste management is to collect waste at the source of generation, recover recyclable materials for recycling, conversion of organic waste to compost and secured disposal of remaining waste. There must be MSW ( Municipality Solid waste) management in every city, and a local solid waste management in every village. Reusing, Recovering, Recycling & Reducing of plastic will help our world survive. Ex- cess usage of plastic bags is spoiling our environment. We can reduce the usage of plastic by many ways by using jute bags, using metal Tiffin boxes etc. Recycling Recycling extracts valuable materials from items that might otherwise be considered trash and turns them into new products. Communities have a variety of recycling programs, such as curbside pickup of recyclables, drop-off centers, buy-back centers that pay us for valuable items and deposit-refund programs. We can also help recy - cling by purchasing products made from recycled material, such as toilet paper made from recycled pulp. Reducing It means reducing your consumption or buying less. Designing items like plastic in ways that use less material is another way to reduce consumption. Using steel cutlery instead of plastic utensils. SESSION 2. PLASTICS - TYPES AND EFFECT ON ENVIRONMENT 73

Reusing Rather than throwing out items like clothing or food jars, consumers can find new uses for them and thereby reduce their consumption of new resources. Composting, using jars to store beverages or leftover food, and trading or selling used DVDs rather than throwing them out are all examples of ways people can reuse. Reusing is the second most effective of the 4Rs; like reducing, it avoids creating waste rather than trying to recycle it once it’s already there. Recover The principle of recover plays major role in this solid waste management. The solid waste should be converted into resources such as electricity, heat, compost and fuel through thermal and biological means. 2.6 Higher Order Thinking Skills Q1. [AS1] Thermoplastics are eco–friendlier than thermosetting plastics. What do you say? Why? [Refer to TB page 50 Q3] A. Thermoplastics are comparatively eco–friendlier than thermosetting plastics, because thermoplastics can be recycled whereas thermosetting plastics cannot be recycled. Q2. [AS2] Imagine what would happen if we did not discover plastics? [Refer to TB page 50 Q2] A. Plastics serves many purposes. Plastics are non – reactive. Plastic is very light, strong, durable and can be moulded into different shapes and sizes. Plastics are generally cheaper than metals. There are many household materials which are made of plastics. In case we have to imagine a world without plastics things would be much costlier, household materials would be made of metals which again would be difficult to maintain. But as we all know that plastic is harmful for the environment. In that case a world without plastics would be much better and environmental pollution free. SESSION 2. PLASTICS - TYPES AND EFFECT ON ENVIRONMENT 74

Q3. [AS7] Indiscriminate usage of plastic is a serious threat to bio–diversity. What are the efforts of Government and Non government organizations in this regard? [Refer to TB page 50 Q5] A. Usage of plastic bags was banned in many cities. This encouraged people to reuse existing plastic bags and increase the use of cloth and jute bags. This helped in max- imizing the use of recyclable plastics and also the enthusiasm of people in recycling existing plastics. Evil effects of plastics: 1. The plastic bags are eaten by some animals and birds. This cause indigestion, suffocation or blocking of digestive tract causing death. 2. The microplastics are translocated from the gut to the circulatory system. 3. The chemical used in plastics affect the aquatic animal also. 4. Most plastic polymers are resistant to bio–degradation. 5. Release of hazardous substances from plastic products to air affect the environment. Efforts of the Government and Non –government Organization: 1. Supreme court of India proclaims that ” Plastic bags are more dangerous than atom bomb for future generations.” With the direction of Supreme court, very thin polythene bags have been banned. Cloth bags are suggested in place of polythene bags. 2. Paper glasses are introduced replacing disposable plastics glasses to protect envi- ronment. 3. Some efforts are taking place to reduce negative consequences of plastics on the environment. SESSION 2. PLASTICS - TYPES AND EFFECT ON ENVIRONMENT 75

4. We can not imagine a world without plastics. But we can adopt recovery mechanisms to convert waste in to a usable resources. We should reduce the uses of plastics. 5. Articles made of plastics may be used again and again for its optimum utilization instead of throwing them. 6. We can recycle plastics to produce new articles. The NGOs are the ones who have brought the Supreme Court’s attention to the indis- criminate usage of plastic bags. 2.7 Suggested Experiments Q1. [AS3] Conduct a flame test to identify Thermo plastics and Thermosetting plastics. [Re- fer to TB page 51 Q1] A. Aim: Identifying thermoplastic and thermosetting plastics by flame test. Materials required: Pair of tongs, spirit lamp, samples of plastics (Collect small pieces of plastics from the objects like comb, tooth brush handle, plastic bucket, handle of utensil, electric switch, piece of melamine of meals plate and coffee mug). Procedure: • Take a spirit lamp and light it. • Clamp one piece of a plastic sample, say a piece of a tooth brush, with tongs. • Place the sample on spirit lamp flame. See the following figure. SESSION 2. PLASTICS - TYPES AND EFFECT ON ENVIRONMENT 76

• Observe the changes during the burning of sample. • Note your observations. • Repeat the procedure with other samples. • Record your observations sample wise. The observation is recorded in the given table. S.No. Name of Softened/ burnt with Thermoplastic / the plas- burning smell Thermoset- tic sample and became hard ting plastic 1 Tooth Softened Thermoplastic brush handle 2 Comb Softened Thermoplastic 3 Piece of Softened Thermoplastic bucket 4 Handle of Burnt with burning smell Thermosetting utensils and became hard plastic 5 Electric Burnt with burning smell Thermosetting switch and became hard plastic 6 Meal plates Softened Thermoplastic Q2. [AS3] Take a wool, silk, cotton thread, bandage, piece of umbrella cloth, thread of sweater, and a piece of rope and carefully conduct a flame test. Based on smell and type of melting, classify them as natural or artificial fibres. [Refer to TB page 51 Q2] A. Wool, thread of sweater, silk all smell like burning hair when burnt. The yarn of all these samples do not melt in the flame. So these are considered as natural fibre. Piece of umbrella cloth and piece of rope, bandage, cotton thread all smell like burning paper when burnt. They are cotton or rayon fibres. SESSION 2. PLASTICS - TYPES AND EFFECT ON ENVIRONMENT 77

The yarn of bandage and cotton thread do not melt in the flame. So they are also considered as natural fibre. The yarn of piece of umbrella cloth and piece of rope melt in the flame. So they are synthetic fibre. 2.8 Suggested Projects Q1. [AS4] Collect the figures made up of thermosetting, thermoplastics used in your daily life and make a poster. [Refer to TB page 51 Q2] A. Students’ activity. Q2. [AS4] Prepare a chart which can explain recycling codes, full names and acronyms of plastic and its usage for various household articles, recycled or not , if recycled what will be made from that. [Refer to TB page 51 Q3] A. Code Acronym Full name Uses 1 PET, PETE Polyethylene Plastic bottles, soft terephthalate drinks and water bottles, food jars, cosmetic containers 2 HDPE High Density Detergent containers, Polyethylene milk and juice bags, grocery bags 3 PVC Vinyl (Polyvinyl Electrical wire Chloride) covering, rain proofing 4 LDPE Low Density Dry cleaning bags, Polyethylene food wraps SESSION 2. PLASTICS - TYPES AND EFFECT ON ENVIRONMENT 78

Code Acronym Full name Uses 5 PP Polypropylene Medicine 6 bottles, 7 PS Packing tapes, Other straws 8 Universal Polystyrene CD and video recycling cases, Egg carton The category of Baby bottles “Other” includes etc. any resin not specifically Generic numbered 1, 2, 3, recycling 4, 5, or 6, or thermosetting combinations of one or more of these resins - Objective Questions (1) The material which is not decomposed by natural process is called (Pg 50;TB Q 3) (A) Non biodegradable material (B) Bio degradable material (C) Polyester (D) Nylon Correct Answer: A (2) What does the following symbol represent? ( Pg 50; TB Q 4) (A) PET (B) HDPE (C) LDPE (D) Others Correct Answer: C SESSION 2. PLASTICS - TYPES AND EFFECT ON ENVIRONMENT 79

—— CCE Based Practice Questions —— AS1-Conceptual Understanding Very Short Answer Type Questions 1. Fill in the blanks. [Refer to Session 3.2 ] (i) Plastics are classified into plastics. . (ii) Plastics take several years to (iii) Like synthetic fibre, plastics are also . (iv) By burning plastics, are released. (v) Polythene is made up of many . (vi) Thermoplastics are preferred over plastics. (vii) A plastic which is softened when heated and hardened when cooled is . (viii) Plastics left in soil results in . (ix) Plastics which are not remouldable are plastics. (x) plastics cannot be recycled. 2. Answer the following questions in one sentence. [Refer to Session 3.1 ] (i) Below is the list of some materials. Write the type of synthetic fibre it is made of. CHAPTER 3. SYNTHETIC FIBRES AND PLASTICS 80

a. Car tyres – b. Bandages – c. Blankets – d. Utensils – e. Ropes – 3. Fill in the blanks. [Refer to Session 3.1 ] (i) Synthetic fibres are called as fibres. (ii) Synthetic fibres are made of . (iii) Rayon is made up of . Wood pulp is the source material for . (iv) Combining of synthetic fibres with two or more fibres is called . (v) Materials that can be decomposed by natural process are called . Short Answer Type Questions 4. Answer the following questions in 3-4 sentences. (i) [(Session 3.1)] PET is a very familiar form of ‘most commonly used synthetic fibre’. Which is that synthetic fibre? Write two uses of that fibre. CHAPTER 3. SYNTHETIC FIBRES AND PLASTICS 81

(ii) [(Session 3.1)] Explain why some fibres are called synthetic or artificial fibres. What are they made up of? Give examples. Long Answer Type Questions 5. Answer the following questions in 6-8 sentences. (i) [(Session 3.2)] What are the biodegradable and non–biodegradable plastics? Give three examples of each. CHAPTER 3. SYNTHETIC FIBRES AND PLASTICS 82

AS2-Asking questions and making hypothesis Short Answer Type Questions 6. Answer the following questions in 3-4 sentences. (i) [(Session 3.1)] Your friend wants to know that what type of fibre it is which is there in her hand. What do you suggest your friend to do to find out the type of fibre? (ii) [(Session 3.1)] Which type of material, you suggest your sister to wear on winter and why? CHAPTER 3. SYNTHETIC FIBRES AND PLASTICS 83

AS3-Experimentation and field investigation Short Answer Type Questions 7. Answer the following questions in 3-4 sentences. (i) [(Session 3.2)] Write an activity to say a bottle is PET bottle. AS4-Information skills and projects Very Short Answer Type Questions 8. Answer the following questions in one sentence. [Refer to Session 3.1 ] (i) Complete the table. CHAPTER 3. SYNTHETIC FIBRES AND PLASTICS 84

Material Code no. PET 1 PS 3 (ii) Complete the table. Usage Material PVC PS CHAPTER 3. SYNTHETIC FIBRES AND PLASTICS 85

Long Answer Type Questions 9. Answer the following questions in 6-8 sentences. (i) [(Session 3.1)] Prepare a table of four synthetic fibres which are used to make household articles from them. CHAPTER 3. SYNTHETIC FIBRES AND PLASTICS 86

AS5-Communication through drawing and model making Short Answer Type Questions 10. Answer the following questions. (i) [(Session 3.1)] Draw the identification codes of – a. Polystyrene b. Low density polythene Long Answer Type Questions 11. Answer the following question. (i) [(Session 3.2)] Draw the six different resin identification codes system and name them. CHAPTER 3. SYNTHETIC FIBRES AND PLASTICS 87

AS6-Appreciation and aesthetic sense, Values Short Answer Type Questions 12. Answer the following questions in 3-4 sentences. (i) [(Session 3.2)] Name three materials which can be easily decomposed. CHAPTER 3. SYNTHETIC FIBRES AND PLASTICS 88

AS7-Application to daily life, concern to bio diversity Short Answer Type Questions 13. Answer the following questions in 3-4 sentences. (i) [(Session 3.2)] Imagine the world without plastics. Write what material can be used instead of plastics in these objects. a. Buckets b. Bottles c. Bags d. Pearls e. Tooth brush f. Plates g. Computer cabinets h. Raincoats i. Umbrella j. Shoes k. Toys l. Covers of electronic gadgets CHAPTER 3. SYNTHETIC FIBRES AND PLASTICS 89

Long Answer Type Questions 14. Answer the following questions in 6-8 sentences. (i) [(Session 3.2)] The Supreme Court said “The plastic bag is more dangerous than the atomic bomb for future generations.” State your reasons to appreciate this statement. CHAPTER 3. SYNTHETIC FIBRES AND PLASTICS 90

Objective Questions AS1-Conceptual Understanding 15. Choose the correct answer. (i) Synthetic fibres are made from the raw materials obtained from . (A) natural fibres (B) animal sources (C)petroleum or petrochemicals (D)plant sources (ii) What is used as an alternative for pearl and jade? (A) Melamine (B) Bakelite (C) Polystyrene (D) Vinyl (iii) Which code represents the carrier bags which cannot be recycled commonly? (A) PET (code 1) (B) HPDE (code 2) (C)PVC (code 3) (D)LDPE ( Code 4) (iv) Which 2 types of plastics occupy major share in recycled plastics? (A) Code 1 and Code 2 (B) Code 2 and code 3 (C)Code 1 and code 3 (D)Code 1 and Code 4 AS2-Asking questions and making hypothesis 16. Choose the correct answer. (i) Which of the following is not a bio–degradable material? (A) Peels of fruits (B) Food stuff (C)Plastic bags (D)Waste paper AS3-Experimentation and field investigation 17. Choose the correct answer. CHAPTER 3. SYNTHETIC FIBRES AND PLASTICS 91

(i) The burning of a yarn results in the smell like burning paper. The yarn is most likely to be . (A) silk or wool (B) cotton or rayon (C)nylon and acrylic (D)cotton or nylon AS4-Information skills and projects 18. Choose the correct answer. (i) Polyamides are made with monomers, hexamethylene diamine and which acid? (A) Hydrochloric acid (B) Tartaric acid (C)Adipic acid (D)Picric acid (ii) The fake fur became commercially available in India in . (A) 1944 (B) 1941 (C) 1924 (D) 1942 (iii) How many types of plastics are available in the world today? (A) 6000 (B) 60,000 (C) 6,00,000 (D) 6,00,000,00 AS5-Communication through drawing and model making 19. Choose the correct answer. (i) Name of this resin is: 92 CHAPTER 3. SYNTHETIC FIBRES AND PLASTICS

(A) PP (B) PS (C) PVC (D) PETE AS6-Appreciation and aesthetic sense, Values 20. Choose the correct answer. (i) The first rayon factory in India was established in . (A) Kerala (B) Maharashtra (C)West Bengal (D) Punjab AS7-Application to daily life, concern to bio diversity 21. Choose the correct answer. (i) Acrylic is generally called . (A) fake fur (B) good fur (C)fibre wood (D) none CHAPTER 3. SYNTHETIC FIBRES AND PLASTICS 93

4. METALS AND NON-METALS SESSION 1 INTRODUCTION AND PHYSICAL PROPERTIES OF METALS AND NON METALS 1.1 Mind Map 1.2 Terminology i. Metals – Metals are materials which are generally shiny in appearance, hard to touch, opaque, and are good conductors of heat and electricity. ii. Non–metals – Non-metals are materials which are generally dull in appearance, soft to touch, transparent, and are bad conductors of heat and electricity. iii. Lustrous – The materials which have bright surfaces and reflect light are called lus- trous. iv. Malleability – The property of materials by which they can be beaten into thin sheets is called malleability. v. Ductility – The property of drawing a material to make fine wires is called ductility. SESSION 1. INTRODUCTION AND PHYSICAL PROPERTIES OF METALS ... 94

vi. Electric conductors – Materials that allow electricity to pass through them are called electric conductors. vii. Sonorous – Materials which produce ringing sound are called sonorous materials. 1.3 Key Concepts i. We use different types of materials in our daily life. ii. Materials are classified as metals and non–metals. iii. Metals have shiny appearance, whereas non–metals have no lustre. iv. Metals are malleable and ductile in nature. v. Metals are good conductors of heat and electricity. Most non–metals are poor con- ductors of heat and electricity. vi. Metals are sonorous. 1.4 Reflection on Concepts Q1. [AS1] Explain the physical properties of metals with suitable examples. [Refer to TB page 63 Q2] A. Metals have metallic lustre. E.g., gold, silver (used in making ornaments) Metals are hard in nature. E.g., iron (making bridges and railway tracks etc) Metals are malleable. E.g., aluminium (making vessels) Metals are ductile. E.g., copper, gold, silver (used in winding, ornaments) Metals are good conductors of heat and electricity. E.g., aluminium (used as wires, boilers) Metals are sonorous. E.g., mixture of copper and tin (used in bells) Q2. [AS1] Explain about ductility. [Refer to TB page 63 Q1] A. The property of drawing a material to make fine wires is called ductility. Most metals are ductile. Copper, Gold, and Silver are examples of ductile metals. The opposite of ductility is brittleness, where a material breaks when tensile stress is applied to lengthen it. Q3. [AS1] Gold jewellery does not become dull. Why? [Refer to TB page 63 Q3] SESSION 1. INTRODUCTION AND PHYSICAL PROPERTIES OF METALS ... 95

A. Silver objects and jewellery becomes black. Copper statues and vessels become dull green. All these metals react with components in air. But gold jewellery does not become dull. Different metals react with the components of air in a different manner at different rates and conditions. Thus they turn black. There are some metals which do not react with the components of air. Gold is one of them. So Gold does not become dull. Q4. [AS5] Draw the diagram of identifying electric conductivity of a material. [Refer to TB page 63 Q4] A. 1.5 Application of Concepts Q1. [AS7] If you are given two samples. How do you distinguish which one is metal and which is non–metal? [Refer to TB page 63 Q1] A. i. By observing its appearance to determine if it is shiny. ii. By hitting with a hammer, to test malleability and ductility. iii. By heating over a candle flame to find out heat conductivity. iv. By inserting in a simple circuit to find out electrical conductivity. Q2. [AS2] Which metals are used in making jewellery? Why? [Refer to TB page 63 Q2] A. Gold, platinum and silver are used in jewellery, because they have a shiny appearance and are non–reactive. They are also highly malleable and ductile. Hence they can be made into required shapes and sizes. Q3. [AS7] Why do cooking pans not have metal handles? [Refer to TB page 63 Q3] SESSION 1. INTRODUCTION AND PHYSICAL PROPERTIES OF METALS ... 96

A. Metals are good conductors of heat. So, if the cooking pans have metal handles they can burn our hands if we touch it while cooking. Hence cooking pans have handles of wood or synthetic material which are bad conductors of heat. Q4. [AS1] Why the bells are made by metals instead of woods? [Refer to TB page 63 Q5] A. Bells are made of metals instead of wood because they have the ability to produce sound when hit hard or dropped down. They show sonorous property. Q5. [AS6] How do you appreciate the efforts of man to use the Metals in making tools? [Refer to TB page 63 Q4] A. Early human beings made their tools from which were easily available –stone and wood. Later, they used the bones of animals. I really appreciate human beings for their effort for discovering metals like copper and iron. Tools made of copper and iron are much stronger than tools made of stone and wood. Metals had the advantage of not just being harder but they can be heated in a fire and moulded or cast into different shapes. So it became possible to make a wider range of tools with such metals. 1.6 Higher Order Thinking Skills Q1. [AS2] You came to know that the Diamond is the hardest material and it is a non metal and similarly Mercury is a soft material and it is a metal. Write down the questions raised in your mind? [Refer to TB page 64 Q1] A. The questions are – i. How is the diamond which is the hardest (and the most lustrous) material a non– metal? ii. Generally metals are hard solids. How is mercury, which is a fluid, a metal? iii. Are there any other substances which are exceptional like Diamond and Mercury? iv. Why is the diamond hardest material in this world? What makes it so? v. Do they possess other characteristics of metal and non metal like conductivity of heat and electricity, malleability, ductility, etc? vi. Are all metals hard? SESSION 1. INTRODUCTION AND PHYSICAL PROPERTIES OF METALS ... 97

vii. What makes mercury so soft and diamond so hard? Q2. [AS7] How the property malleability of metals is used in our daily life? [Refer to TB page 64 Q5] A. Since metals are malleable, they can be beaten and converted into thin sheets, they are used in preparing different types of vessels (utensils) and sheets (for construction etc.) which we are using in our daily life. 1.7 Suggested Experiments Q1. [AS3] Identify the electric conductivity of materials with an experiment. [Refer to TB page 64 Q3] A. Aim : To identify electric conductivity of a material. Materials Required : Battery, Copper wire, Battery, Bulb Procedure : i. Arrange an electric circuit with a battery and a bulb. ii. Close the circuit using an iron nail as shown in figure. iii. Observe whether the bulbs glows or not. iv. Record your observation in table. v. Repeat the same experiments using other samples and record your observations in the same table. SESSION 1. INTRODUCTION AND PHYSICAL PROPERTIES OF METALS ... 98