Q3Short answer
Synthetic Fibres and Plastics
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d
Chapter 3 – Synthetic Fibres And Plastics
Class 8 Science · 27 questions · 27 with answers
Questions
Q4Multiple choice
Which is a thermosetting plastic?
- (a)Melamine
- (b)Polythene
- (c)PVC
- (d)Nylon
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(a) Melamine
Q5Multiple choice
The material similar to silk in appearance is
- (a)Nylon
- (b)Rayon
- (c)Polyester
- (d)Terylene
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(b) Rayon
Q6Multiple choice
The most suitable material for the preparation of handles of cooking utensils is
- (a)Polythene
- (b)PVC
- (c)Nylon
- (d)Bakelite
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(d) Bakelite
Q7Multiple choice
Which of the following is not a common property of plastics?
- (a)Non-reactive
- (b)Light in weight
- (c)Durable
- (d)Good conductor of electricity
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(d) Good conductor of electricity
Q8Multiple choice
Which of the following represents the correct match for items in Column A with those in Column B. Column A Column B I. Nylon (i) Thermoplastic II. PVC (ii) Thermosetting plastic III. Bakelite (iii) Fibre 14 E XEMPLAR PROBLEMS
- (a)I-(ii), II-(iii), III-(i)
- (b)I-(iii), II-(i), III-(ii)
- (c)I-(ii), II-(i), III-(iii)
- (d)I-(iii), II-(ii), III-(i)
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(b) I-(iii), II-(i), III-(ii)
Q9Multiple choice
Which of the following groups contain all synthetic substances?
- (a)Nylon, Terylene, Wool
- (b)Cotton, Polycot, Rayon
- (c)PVC, Polythene, Bakelite
- (d)Acrylic, Silk, Wool
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(c) PVC, Polythene, Bakelite
Q10Multiple choice
The material which is commonly used for making kitchen containers is
- (a)PVC
- (b)Acrylic
- (c)Teflon
- (d)PET
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(d) PET
Q11Very short answer
Cotton is a natural polymer. What is its chemical name?
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Cellulose.
Q12Very short answer
A synthetic fiber which looks like silk is obtained by chemical treatment of wood pulp. It is, therefore, known as artificial silk. What is its common name?
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Rayon.
Q13Very short answer
Terrycot is made by mixing two types of fibres. Write the names of the fibres.
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Terylene and cotton.
Q14Very short answer
Plastic articles are available in all possible shapes and sizes. Can you tell why?
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Plastic is easily moldable so the articles can be made in any shape and size.
Q15Very short answer
Plastic is used for making a large variety of articles of daily use and these articles are very attractive. But it is advised to avoid the use of plastic as far as possible. Why?
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Due to its non-biodegradable nature it causes environmental pollution.
Q16Very short answer
Why is it not advisable to burn plastic and synthetic fabrics?
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Burning of plastic and synthetic fabrics produces lots of poisonous gases causing air pollution.
Q17Multiple choice
Select the articles from the following list which are biodegradable.
- (a)paper
- (b)woolen clothes
- (c)wood
- (d)aluminium can (e) plastic bag (f) peels of vegetables
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(a) paper
(b) woolen clothes
(c) wood
Q18Very short answer
A bucket made of plastic does not rust like a bucket made of iron. Why? S YNTHETIC FIBRES AND PLASTICS 15
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Plastic is a non-reactive material. It does not react with air and water and thus does not rust. SHORT ANSWER QUESTIONS
Q19Short answer
Rohit took with him some nylon ropes, when he was going for rock climbing. Can you tell why he selected nylon ropes instead of ropes made of cotton or jute?
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Nylon ropes are strong, elastic and lighter as compared to cotton and jute ropes.
Q20Short answer
A lady went to the market to buy a blanket. The shopkeeper showed her blankets made of acrylic fibres as well as made of wool. She preferred to buy an acrylic blanket. Can you guess why?
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Acrylic blankets are cheap, light in weight, more durable and are available in variety of colours and designs. They can be easily washed at home.
Q21Short answer
PVC (polyvinyl chloride) is a thermoplastic and is used for making toys, chappals, etc. Bakelite is a thermosetting plastic and is used for making electrical switches, handles of various utensils, etc. Can you write the major difference between these two types of plastics?
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Thermoplastics get deformed easily on heating and can be bent easily on heating. On the other hand thermosetting plastics when molded once can not be softened on heating.
Q22Multiple choice
Fill in the blanks.
- (i)A polymer is a chain of many small units joined together which are called ______.
- (ii)The synthetic fibres are also known as ______ fibres.
- (iii)The first fully synthetic fibre was ______.
- (iv)A fibre similar to wool is ______. (v) A plastic used for making crockery is ______.
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(i) A polymer is a chain of many small units joined together which are called ______.
(iv) A fibre similar to wool is ______. (v) A plastic used for making crockery is ______.
(ii) The synthetic fibres are also known as ______ fibres.
(iii) The first fully synthetic fibre was ______.
Q23Multiple choice
Match items in List A with the items of list B. List A List B (a) nylon
- (i)non-stick coating (b) PET
- (ii)electric switches (c) rayon
- (iii)parachutes (d) thermosetting plastics
- (iv)polyester (e) teflon (v) artificial silk
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(i) non-stick coating (b) PET
(iii) parachutes (d) thermosetting plastics
(ii) electric switches (c) rayon
(iv) polyester (e) teflon (v) artificial silk
Q24Multiple choice
Unscramble the jumbled words given below, related to synthetic materials.
- (a)anory
- (b)lopmery
- (c)relyteen
- (d)laspict (e) yespolter (f) felton 16 E XEMPLAR PROBLEMS
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(a) anory
(d) laspict (e) yespolter (f) felton 16 E XEMPLAR PROBLEMS
(b) lopmery
(c) relyteen
Q25Multiple choice
Indicate whether the following statements are True or False. Also write the false statements in their correct form.
- (i)The fabric terywool is obtained by mixing terylene and wool.
- (ii)Synthetic fibres do not melt on heating.
- (iii)It is risky to wear synthetic clothes while working in the kitchen.
- (iv)Most of the plastics are biodegradable.
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(i) The fabric terywool is obtained by mixing terylene and wool.
(ii) Synthetic fibres do not melt on heating.
(iii) It is risky to wear synthetic clothes while working in the kitchen.
(iv) Most of the plastics are biodegradable.
Q26Long answer
Write the importance of synthetic polymers in our life.
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Hint: Write uses of synthetic polymers like nylon, acrylic, terylene, PET, plastics, etc.
Q27Long answer
Despite being very useful it is advised to restrict the use of plastic. Why is it so? Can you suggest some methods to limit its consumption?
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Hint: Plastic is a non-biodegradable material and as such it causes land pollution. At the same time burning such materials in the form of garbage causes serious air pollution. Reducing it’s use, reusing it for some other purpose and recycling may limit its overall consumption and reduce environmental pollution.
Q28Long answer
Write an activity to show that synthetic fibres are stronger than the cotton fibres.
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Hint: By hanging weight with the threads of same thickness of any synthetic fibre and cotton separately will show that more weight is required to break a synthetic thread. (Also see activity 3.1 of NCERT science book of class VIII).
Q29Long answer
Complete the crossword given below with the help of clues. S YNTHETIC FIBRES AND PLASTICS 17 Across 1. Substance used as synthetic wool (7) 2. A plastic used for making containers and carry bags (9) 3. Substance made up of large number of smaller molecules (7) 4. Another name for this compound is artificial silk (5) Down 5. A type of fibre obtained naturally from cocoon (4) 6. A synthetic fibre classified as polyester (8) 7. A polymer used for making rope (5)
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118 E XEMPLAR PROBLEMS