SYNTHETIC FIBRES AND PLASTICS
Question 1. Explain why some fibres are called synthetic.
Answer- Because synthetic or man-made fibres are obtained from petrochemicals by human.
Question 2. Mark (✓) the correct answers.
Rayon is different from synthetic fibres because:
(a) It has a silk like appearance.
(b) It is obtained from wood pulp. ✓
(c) Its fibres can also be woven like those of natural fibres.
Question 3. Fill in the blanks with appropriate words.
(a) Synthetic fibres are also called artificial or man-made fibres.
(b) Synthetic fibres are synthesized from raw material called petrochemicals.
(c) Like synthetic fibres, plastic is also a polymer.
Question 4. Give examples which indicate that nylon fibres are very strong.
Answer- They are used to make parachutes and ropes for rock climbing.
Question 5. Explain why plastic containers are flavored for storing food.
Answer- The main advantage of using plastic for storing food are
a.Plastic has light weight.
b. Good strength.
c. Easy to handle.
d. Plastic is non reactive .
Question 6- Explain the difference between thermoplastic and thermosetting plastics.
Answer-
Thermoplastic Thermosetting plastics
1. Thermoplastic can be bent easily. 1. Thermosetting plastic cannot be bent easily
2. Thermoplastic can be softened easily by heating. 2. Thermosetting plastic cannot be softened by heating.
3. It can be reshaped. 3. It cannot be reshaped once moulded.
Question 7. Explain why the following are made of thermosetting plastics.
(a) Saucepan handles
(b) Electric plug/ switches /plug boards
Answer- (a) Saucepan handles: Saucepan handles are made from the thermosetting plastics because these are bad conductors of heat and electricity. They do not bend or deform on heating.
(b) Electric plug/ switches /plug boards : Thermosetting plastics such as bakelite are poor conductors of heat and electricity. Therefore, they are used for making electric plugs, switches, plug boards, etc.
Question 8. Categorise the materials of the following products into ‘can be recycled’ and ‘cannot be recycled’.
telephone instruments, plastic toys, cooker handles, carry bags, ball point pens, plastic bowls, plastic covering on electrical wires, plastic chairs, electrical switches.
Answer-
Can be Recycled Cannot be Recycled
Plastic toys Telephone instruments
Carry bags Cooker handles
Ball point pens Electrical switches
Plastic bowls
Plastic covering on electrical wires
Plastic chairs
Question 9. Rana wants to buy shirts for summer. Should he buy cotton shirts or shirts made from synthetic material? Advise Rana, giving your reason.
Answer- Rana should buy shirts made from cotton. This is because cotton is a good absorber of water. It absorbs the sweat coming out of our body and exposes it to the environment thereby cooling our body.
Question 10- Give examples to show that plastics are noncorrosive in nature.
Answer- 1. Plastics don't react with acids or bases which are kept in them. The cleansing chemicals that we use at home are stored in plastic bottles, instead of metal containers.
2. Plastics don't react with air and water. For example: chairs, buckets all are made from plastics.
Question 11: Should the handle and bristles of a tooth brush be made of the same material? Explain your answer.
Answer- No, the handle and bristles of a toothbrush cannot be made of the same material. This is because the handle has to be hard and strong while bristles have to be soft and flexible.
Question 12. ‘Avoid plastics as far as possible’. Comment on this advice.
Answer- This is because plastics are non-biodegradable. The waste created by plastics is not environmentfriendly, which on burning release poisonous gases. Plastics may take years to degrade and keep on piling up and hence are an environmental hazard for the living community.
Question 13. Match the terms of column A correctly with the phrases given in column B.
Question 14. ‘Manufacturing synthetic fibres is actually helping conservation of forests’. Comment.
Answer- Raw materials for natural fibres are mainly derived from plants and this means cutting a lot of trees. This leads to deforestation. But raw materials of synthetic materials are mainly petrochemicals. Hence, manufacturing synthetic fibres helps in the conservation of forests.
Question 15. Describe an activity to show that thermoplastic is a poor conductor of electricity.
Answer- Make an electric circuit as given in figure. First, we connect the two ends of the copper wires with the metal rod. Next, we replace it with the PVC rod. The LED bulb glows when the metal rod is connected but does not glow when the PVC rod is connected. Hence we can say that thermoplastic is a poor conductor of electricity.
ONE MARK MCQs
1. Navkiran learned about natural fiber in school today. How will she find out the given fiber is natural or not?
a) By smelling the fiber b) By looking at the fiber
c) By burning the fiber (✓) d) None of these
2. Gurinder noticed today that electrical switches are made up of special material. Which material is used to make electrical switches?
a) Wood b) Rubber c) Iron d) Thermosetting plastic (✓)
3. Harpreet has two shirts, one of which is made of cotton and other of silk. Out of both the shirts, which will absorb more water?
a) Silky b) Cotton (✓) c) Both equally d) Cannot say anything
4. During her class today, Mandeep learned that there is a material which turns its shape on heating.Can you tell the name of that material?
a) Plastic b) Thermo plastic (✓) c) Acrylic d) All of these
5. Ravi’s mother always bought PET bottles to store water. Where else PET is used?
a) Utensil b) Wires c) Film d) All of these (✓)
6. Varinder saw a board of “plastic free city” while he visited Chandigarh. Plastic is hazardous to our environment because
a) Plastic is biodegradable b) Plastic is not strong
c) Plastic is non-biodegradable (✓) d) All of above
7. Sukhjinder came to know today that we get silk from silk worm. On which tree does silk worm lives on?
a) Mulberry tree (✓) b) Babool tree c) Cotton plant d)Neem tree
8. Amandeep’s mother uses plastic container to store pickle. She does this because
a) Plastic container is cheap b) Plastic doesn’t react with air
b) Pickle doesn’t turn poisonous d) All of above(✓)
9. Ramandeep told her friend that she bought a sweater made up of acrylic wool. Is sweater made up of acrylic wool cheaper or costlier that natural wool?
a) Costlier b) Cheaper(✓) c) Equal price d) Can’t say anything
10. Alka was drying some clothes after washing. After some time she noticed that few clothes had fully dried, while other clothes were still wet. Why were some clothes still wet?
a) they were made of synthetic fibers b) they were made of cotton (✓)
c) they were made of silk d) none of these
11. The teacher taught the students about the different types of natural and synthetic fibers and asked them which is the strongest fibre?
a) Nylon(✓) b) Rayon c) Polyester d) Cotton
12. While distinguishing between synthetic and natural fibers, Balkaran burnt a piece of fiber given by the teacher and noticed that the sample burnt slowly and shrinked into a solid mass. Which fiber is this?
a) Cotton b) nylon(✓) c) wool d) none
13. Teacher taught about nylon fiber in class. Nylon is used to make.
a) Socks b) ropes c) Tents d) all of above (✓)
14. Terylene is an example of:-
a) Nylon b) Rayon c) Polyester(✓) d) None of these
15. The teacher explained that when small subunits (monomers) form bonds among each other and form a larger unit which is called as ___________.
a) Cellulose b) polymer(✓) c) nylon d) none of these
16. Name that fiber which has same characteristics as that of silk.
a) Nylon b) Rayon (✓) c) Polyester d) None of these
17. Navkiran observed that melamine is ………………………….. plastic
a) Thermosetting b) Thermoplastic (✓) c) Polyester d) None of these
18. Sarabjit wants to buy some shirts to wear during the summer season. Which fabric shirts would you suggest him to buy?
a) made from synthetic fibers b) Silk c) cotton (✓) d) All of these
19. Meera’s mother told her that it is not advisable to wear clothes made of synthetic fibers while cooking food in kitchen because –
a) they are costly b) they are difficult to wash
c) it’s dangerous to wear them near fire (✓) d) none of these
20. The teacher told the students that in order to keep our environment neat and clean we must follow ___________ principle
a) Swachh Bharat b) 3 R (✓) c) 2 R d) none
21. Which synthetic fiber is also known as artificial fiber?
a) Nylon b) terylene c) rayon d) all the above (✓)
22. Mandeep came to know that cotton is also a polymer known as cellulose. Name the monomers (subunits) of cellulose.
a) Glucose (✓) b) maltose c) rayon d) protein
23. Prabhsimran learnt from his teacher that nylon is an artificial (man-made) fiber which is prepared without using any natural raw material. Of which raw material is nylon prepared ?
a) air, coal and water b) coal and petroleum (✓) c) cotton and silk d) none of these
24. All the synthetic (artificial fibers) are prepared by different methods from a special type of raw material known as ______________.
a) petrochemicals (✓) b) cellulose c) bakelite d) all of these
25. Avneet came to know after reading the lesson that plastic is also a polymer in which the monomer units are linked linearly in some while they are __________________ in the others.
a) Linear b) crosslinked (✓) c) spiral d) none of these
26. While cooking in a microwave, containers made of special plastics are used? Why is it done so?
a) they are cheap b) special plastic remains unaffected of heat in the microwave (✓)
c) any utensil can be used d) all of these
27. Why should the use of plastics be reduced?
a) its costly b) its non-biodegradable c) its harmful to environment d) both ‘b’ and ‘c’ (✓)
28. Nowadays we use carry bags made from cloth or paper in order to bring commodities to home from market. Why according to you is the use of plastic banned?
a) they are cheap b) they are biodegradable
c) they are strong as compared to natural fibers d) they are non-biodegradable (✓)
29. Teacher told Dharminder that there is a synthetic fiber which is synthesized from renewable source. Name the fibre?
a) Nylon b) polyester c) rayon (✓) d) acrylic
30. Naresh is planning to climb a mountain. Out of the following, which rope must he used?
a) Silk rope b) Cotton c) Nylon Rope (✓) d) None of these
More questions-
Questions
Very Short Answer
Q1) Define polymer?
Q2) How fabrics are made?
Q3) What are synthetic fibres?
Q4) Why rayon is mixed with cotton?
Q5) How polycot is different from polywool?
Short Answer
Q6) What do you understand by ester?
Q7) Why cellulose is called polymer?
Q8) What do you mean by polyethylene terephthalate and its uses?
Q9) What are the characteristics of the synthetic fibre?
Q10) Why plastics are poor conductor of electricity?
Long Answer
Q11) Explain the characteristics of Plastics?
Q12) State the difference between biodegradable and non-biodegradable?
Q13) Difference between natural fibres and synthetic fibres?
Q14) State the difference between thermoplastics and thermosetting plastics?
Q15) Explain the types of synthetic fibres?
