INTRODUCTION
The clothes which we wear are made up of fabrics. Fabrics are made from fibres.
A fibre is a thread or filament like material which is so strong & flexible that can be converted into clothes, ropes and nets etc.
They are of two kinds :- (1) Natural fibres (2) Synthetic fibres
(1) Natural fibres : - These are long thin threads which are obtained from natural polymers obtained from animals or plants eg.
(i) Cotton & Jute – From cell wall of plant cells (Cellulose, is natural polymer)
(ii) Wool – From the fleece of sheeps & goats
(iii) Linen – From stalk of a plant (Flax)
(iv) Silk – From cocoons of silk worm.
(2) Synthetic fibres :- Those fibres which are synthetically man made, and are polymer of small units are called synthetic fibre.
· The word polymer is made up of two Greek words poly which means many and mer means unit.
· All the synthetic fibres are prepared from raw materials of petroleum origin called petrochemical. eg. Nylon, Polyester etc.
POLYMERISATION
Synthetic fibres are polymers. A polymer is a large molecule formed by the combining of many small molecules, each of which is called a monomer. The process of combining the monomers to form a polymer is called polymerisation. Polymerisation can be of various kinds, for example : addition polymerisation and condensation polymerisation.
Types of Synthetic fibres
1. Rayon 2. Nylon 3. Polyester 4. Acrylic 5. Spandex
1. RAYON
It was prepared by chemical treatment (viscose process) of wood pulp (cellulose). It is also called artificial silk because it resembles in appearance like natural silk.
Properties :
(i) Rayon can absorb sweat because of its tendency to absorb moisture. So it is preferred over other synthetic fabrics in summer season.
(ii) It is shiny and lustrous and resembles to silk.
(iii) It can be dyed in a wide variety of colours.
Uses :
(i) Rayon is mixed with cotton to make bed sheets and mixed with wool to make carpets.
(ii) Shirts, ties and linings are made up of rayon fibre.
(iii) It is used to manufacture tyre cords
(iv) It is used to make bandages and surgical dressings.
2. NYLON
(i) Nylon was first introduced in 1930s.
(ii) It was developed in Newyork (Ny) & London (Lon) so it was named as Nylon.
(iii) It was the first man made fully synthetic fibre.
(iv) It is a polymer made from two monomers, a diacid and a diamine, by the process called condensation polymerisation.
(v) There are various nylons such as nylon 6, nylon 6-6 and nylon 5-10.
Properties :
(i) Nylon has high strength and high elasticity. It does not lose strength even after repeated use.
(ii) It is lustrous and easy to wash.
(iii) It absorbs very little water hence known to have drip-dry property.
(iv) It is wrinkle resistant and keeps permanent creases.
(v) It is moth and mould resistant.
(vi) It is light, fine and durable.
Uses :
(i) In making socks, sarees, shirts and other garments.
(ii) It is used to blend with wool to increase the strength & used in making carpets.
(iii) Used to make tents, parachutes, umbrella, fishing nets, climbing ropes, tyre cord, strings for sports goods.
(iv) It's fibres are used for making tooth brush, car seat belt, slipping bags and curtains.
(v) It is used to make machine parts.
MAKING NYLON 6-6 : Nylon 6-6 is a commerically successful variety of nylon made from adipic acid and hexamethylene diamine. First 6 in 'nylon 6-6' refers to the 6 carbons of adipic acid and the second 6 to the 6 carbons of the diamine.
Adipic acid + hexamethylene diamine ® nylon 6-6 + water
The reaction is carried out at high temperature and pressure. The molten nylon 6-6 is then forced through a spinneret, with very fine holes into air where it hardens into filaments. The fibres are then stretched upon cooling.
3. POLYESTER
It is made of repeating units of a chemical called "ester" which has fruit like smell. Most polyester fabrics have excellent wash and wear characteristics and therefore requires minimum care eg. Terylene and Dacron.
Blended fibres :
Fabrics are sold by names like polycot, polywool, terrycot, etc. As the name suggests, these are made by mixing two types of fibres.
Polycot ® Polyester + Cotton.
Terrycot ® Terrylene + Cotton.
Polywool ® Polyester + Wool
Properties :
(i) It absorbs very little water so dry quickly.
(ii) It is strong, light weight, wrinkle resistant and elastic fibre.
(iii) It is not attacked by moths and ordinary chemicals.
(iv) It can be drawn in to very fine fibres that can be woven like any other yarn.
Uses :
(i) Polyester fibres are used in manufacture of textiles.
(ii) Terry wool, a blend of terylene and wool, is used for making suits,
Terrycot is used for making skirts, shirts and other dress materials.
(iii) It is used to make light weight sails, conveyor belts.
(iv) Polyester films, which is known as "mylar" are used for making magnetic recording tapes in audio cassettes, video cassettes and floppy discs.
Making Polyester : PET (polyethylene terephthalate), the commonly used polyester, is made from two monomers.terephthalic acid and ethylene glycol, by the process called condensation polymerisation
terephthalic acid + ethylene glycol ---> polyethylene terephthalate (PET) + water.
4. ACRYLIC
Synthetic fibre prepared from acrylonitrile (Monomer unit). Acrylic fibre is also known as polyacrylonitrile ("PAN") or "Orlon" or Acrilan"
Properties :
(i) It is warm, soft, light and flexible fibre.
(ii) It closely resembles to wool in its properties & cheaper than natural wool.
(iii) Acrylic yarn can be easily knitted.
(iv) They are available in variety of colours.
Uses :
(i) Acrylic fibre is used for making sweaters, socks & shawls.
(ii) It is used for making carpets and blankets.
5. SPANDEX
Spandex is known for its high elasticity which makes it suitable for use in clothes, that require snug fitting eg swimming costumes. It is also known as "LYCRA" .
When spandex is blended with cotton fabrics, stretched fabric is obtained which is used for making T-shirts and caps.
Uses : It is used in the making of costumes, caps, T-shirts etc.
ADVANTAGES AND DISADVANTAGES OF SYNTHETIC FIBRES
PLASTICS
Material that can be shaped by applying heat and pressure. Plastic means easy to mould. Plastic is a polymeric substance that can be moulded when soft and then hardened to produce a durable article. It is made soft by applying heat and pressure before moulding.
Types of Plastics :- On the basis of their reaction to heat, all types of plastic can be classified into two groups.
(i) Thermoplastics (ii) Thermosetting plastics
(i) Thermoplastics :- Those plastics which can be melted by heating and moulded into desired shapes and sizes, repeatedly are called thermoplastics. On heating these softens and on cooling they becomes hard. This cyclic process of heating, moulding & cooling is adopted to get desired shaped article.
e.g Polythene, PVC, Nylon, Terylene and Polystyrene etc.
(ii) Thermosetting Plastics :- These are harder and stronger than thermoplastics and can retain their shape and size even at high temperature. These polymers once set in a given shape on heating, can not be resoftened or remelted on being reheated. eg. Bakelite, Melamine.
General Properties :-
(i) Plastic can be recyled, reused, coloured, melted, rolled into sheets or made into wires.
(ii) Plastic is non-reactive with moisture & air and insoluble in water. It is not corroded easily.
(iii) Plastic is light in weight, strong & durable and moulded into different shapes and sizes.
(iv) Plastics are poor conductor of heat and electricity, that's why electrical wire coverings, handles of screw drivers and frying pans are made of plastics.
Uses :
Plastic and Environment :
(i) Plastic takes several years to decompose so it is not environment friendly. It causes environmental pollution (Air, Water & Land)
(ii) (a) When plastic burns, it releases lots of poisonous gases into atmosphere causing air pollution.
(b) When plastic wastes are dumped in water they cause water pollution.
(c) Accumulation of plastic waste on road sides & collection of ugly dumps causes many diseases to humans and animals.
Q. Categorise the materials of the following products into "can be recycled" and "can not be recycled"
Telephone instruments, plastic toys, cooker handles, carry bags, Ball point pens, Plastic bowls, Plastic covering on electrical wires, plastic chairs, electric switches.
Q. Rana wants to buy shirts for summer. Should he buy cotton shirts or shirts made from synthetic material? Advise rana, Giving your reason?
Problems and solutions associated with Plastic disposal :
Problems : Environmental and health hazards problems arises with their disposal because they are non-biodegradable. Accumulation of plastics is a serious problem, because most of the method used to dispose them results in some type of pollution to the environment.
(i) Buried plastic materials prevent rain water from seeping into earth, so plant growth is affected in those areas.
(ii) Plastic waste may end up in littering road sides, floating in lakes and streams and collecting in ugly dumps. These provides homes for many diseases.
(iii) When wastes are dumped in water. It causes water pollution through toxic substances present in plastics. It can cause death or reproductive failure in fish and other aquatic animals.
(iv) When cows eats garbage they swallow materials like polythene bags and wrappers of food. It chokes the respiratory system of cows and forms a lining in their stomach and can be the cause of their death.
(v) The polybags thrown carelessly here and there are responsible for clogging the drains.
Solutions :
(i) Avoid the use of plastics as far as possible.
(ii) Use cotton or jute bags instead of plastic bags when we go for shopping.
(iii) Biodegradable and Nonbiodegradable waste should be collected separately and disposed off separately.
(iv) Recycle the plastic waste. Take care in collection, sorting and processing the plastic waste with this aim that it can be used in manufacturing of other products.
(v) Knowledge should be given to people about "green bin" and "blue bin" provided by municipality for separation of biodegradable waste such as food items (Green bin) and Nonbiodegradable waste such as plastics (Blue bin).
(vi) People should also be advised to follow 4R principles. The "4R" principles are –
(a) Reduce (b) Reuse (c) Recycle (d) Recover
It will make environment friendly.
To overcome the problem of disposal of solid polymer waste, scientists were trying to make such type of plastics which should be "biodegradable" (decomposed by microorganisms) and "Photodegradable" (decomposed by sunlight) some polymers have been made. examples are –
(i) Poly b – Hydroxybutyrate – co – b – Hydroxy valerate (PHBV)
It is biodegradable and used in speciality packaging, orthopaedic devices and in controlled release of drugs.
(ii) Nylon – 2 – Nylon – 6 (Biodegradable)
To identify the plastics, numbers have allotted to different types of plastics. The principle used for it is, smaller the number, easier is to recycle.
IMPORTANT POINTS
1. Soap has two-headed molecule, i.e., hydrophilic (have affinity with water) and hydrophobic (repel water molecule).
2. Soaps do not produce lather in hard water.
3. Detergents are made chemically from petroleum hydrocarbons.
4. Household detergents are mostly alkaline in nature.
5. Ammonia is main basic constituent of nitrogenous fertilizers.
6. Weedicides are used to eliminate weeds.
7. Use of DDT and BHC is banned in some countries.
8. DDT and BHC are pesticides having long lasting effects.
9. Some pesticides enter in food chains, thus cause serious health hazards.
10. Glass is made by fusing sand (silica) with sodium carbonate and calcium carbonate.
11. Many man-made substances are not biodegradables.
12. Formica and Melamine are generally used for making cups and crockery.
13. Thermosets do not soften upon heating.
14. Bakelite is a common example of thermoset.
15. Natural fibres like cotton is obtained from plant, while wool and silk fibres are obtained from animals.
16. Cinder concrete is used to build bridges.
17. Glasses are made from silica and silicates.
18. Plate glass is used in shop windows and doors.
19. Bullet proof glass is made by safety glass and is laminated with a thin layer of plastic (polyvinyl butyral).
20. Lead crystal glass has high refractive index.
21. Boro silicate glass is resistant to heat.
22. Photochromic glasses contain silver iodide.
23. Teflon is used as a nonstick coating for cooking utensils.
24. Rayon has silky look and is similar to cotton.
25. The rearing of silkworms for obtaining silk is called sericulture.
26. Silk fibres are made up of a protein.
27. Granite stones are very strong and long lasting.
28. Stones are readymade building material.
29. Soda-lime silica glass is used to make bottle, crockery, mirrors, etc.
30. Rayon is made from wood pulp while nylon is made from coal, air and water.
31. Nylon by far the most used synthetic fibre is prepared from coal, water and air.
32. Many articles like socks, ropes, tents, parachute etc., are made from nylon. A nylon thread is stronger than a steel wire.
33. Glass fibres are woven with cotton fibres to make water-proof and fire-proof sheets.
34. Water proof sheet layers are joined together by adhesives to form fibre glass material.
35. Optical fibres are very fine glass tubes.
36. Optical fibres are used in endoscopy.
37. Ceramic pottery is produced by treating clay at high temperatures.
38. The simplest and oldest type of pottery is earthenware.
39. Terra cotta is a primitive unglazed kind of pottery.
40. Porcelain is made from white clay and is translucent.
41. Porcelain was first made in China and is also known as Chinaware or Bone China.
42. Porcelain is used as insulator for high tension electric cables.
43. Plant cellulose is a natural polymer.
44. Wool and silk are also natural polymers having long chains of protein molecules.
45. Polythene is thermoplastic and is used for packing milk.
46. Polystyrene is very light, when blown contains many air bubbles.
47. Perspex is extermely light and transparent.
48. Polyester is made up of esters. Polycot, polywool, terry cot etc., are products prepared by mixing two kinds of fibres.
49. Synthetic fibres are durable, less expensive and dry up fast.
50. Plastic because of mouldability finds versatile use. Thermoplastics like PVC and polythene can be remoulded, while thermosetting plastics (like bakelite and melamine) can't be remoulded.
51. Thermosetting plastics are used as kitchen ware and also for electrical switches and handles.
52. Plastic is non-reactive and doesn't corrode easily, hence suitable as containers of food, but are non-biodegradable.
53. Waste created by plastics is not ecofriendly. Burning of plastic release poisonous gases. Hence these shouldn't be disposed by burning.
54. Nagarjunsagar dam on river Krishna is made of granite stones.
55. Most famous temples of South India are made of granite stones.
56. Red Fort at Delhi and palaces of Fatehpur Sikri (Agra) are made of sandstone.
57. Bricks were extensively used by the people of the Indus Valley Civilization.
58. The famous Taj Mahal at Agra is made of white marble.
59. Cement is manufactured from silica, alumina, limestone and iron oxide.
60. In 1824, British engineer Joseph Aspdin discovered Portland cement.
61. Gypsum is mixed during manufacture of cement to slow the setting (hardening) process.
62. Glasses are super cooled liquids.
63. We should reduce use of plastic.
64. Polybags carelessly thrown are responsible for clogging the drains and also health problems for animals since cows and other stray animals sometimes swallow plastic bags and choke their respiratory system.
65. Use the 4R principle for use of plastic. Reduce, reuse, recycle and recover.
SOLVED EXAMPLES
Ex.1 Explain why some fibres are called synthetic.
Sol. Explain fibres are called synthetic fibre because they do not occur in the nature.
Ex.2 Mark the correct answer.
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.
Sol. (b) It is obtained from wood pulp.
Ex.3 Fill in the blanks with appropriate words.
(a) Synthetic fibres are also called _______ or __________ fibres.
(b) Synthetic fibres are sysnthesised from raw material called __________
(c) Like synthetic fibres, plastic is also a _________ .
Sol. (a) man-made, artificial fibres. (b) Petrochemicals. (c) Polymer.
Ex.4 Give examples which indicate that nylon fibres are very strong.
Sol. Nylon fibres are strong so they are used for making parachutes and ropes for rock climbing.
Ex.5 Explain why plastic containers are favaoured for storing food.
Sol. Advantages of plastic containers.
(a) Plastics do not react with food items.
(b) Plastics are strong and light.
(c) They are easy to handle and safe.
Ex.6 Explain the difference between thermoplastics and thermosetting plastics.
Sol. Differences :
Ex.7 Explain why the following are made of thermosetting plastics.
(a) Saucepan handles.
(b) Electric plugs /switches /plug boards
Sol. (a) The handles of saucepan are made of thermosetting plastics becausse it is a bad conductor of heat and do not get heated up while cooking.
(b) Electric plugs/switches/plug boards are made up of thermosetting plastics, because it is a bad conductor of electricity. The electric current does not passs through such plastics.
Ex.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, plastics chairs, electrical switches.
Sol. Can be recycled : Toy, carry bags, plstics ball point pen, plastic chairs, electric wire covering.
Cannot be recycled : cooker handles, electric switches, telephone instruments.
Ex.9 Rana wants to buy shirts for summer, Should he buy cotton shirts or shirts made from synthetic material ? Advise Rana, giving your reason.
Sol. Rana should buy cotton shirts for summer because cotton is a bad conductor of heat. It does not allow the transmission of heat from or to the body, thus protects body from heat. It has more capacity to hold moisturethan the synthetic clothes. So, it retains the sweat of the body and keeps it cool. So Rana should buy cotton shirts.
Ex.10 Give examples to show that plastics are noncorrosive in nature.
Sol. Plastics are noncorrosive in nature :
(i) They do not react with any substances.
(ii) Plastics do not react with air and water which are essential for corrosion.
(iii) They do not show any chemical reaction.
Ex.11 Should the handle and bristles of a tooth brush be made of the same materials ? Explain your answer.
Sol. No, heandle and bristels of a tooth brush should not be made of the same materials because handle should be hard while bristels should be made of the soft materials. Bristles should be soft so that it does not harm the gum of teeth. Handle gives the firm grip so it should be made of hard material.
Ex.12 ‘Avoid plastics as far as possible.’ Comment of this advice.
Sol. Avoid the use of plastics as far as possible. Plastics are non -biodegradable materials. So sue of plastics is harmful for our environment. The plastics cannot be finally disposed off. Thus, plastics should be avoided as far as possible.
Ex.13 Match the terms of Column A correctly with the phrases given in Column B.
Sol.
Ex.14 ‘Manufacturing synthetic fibers is actually helping conservation of forests. Comment.
Sol. The natural fibres required the raw materials from plants and animals. so they lead cutting of trees and killing of animals. synthetic fibres are made up of chemicals and these chemicals are not available in forests. so manufacturing sysnthetic fibres is actually helping conservation of forests.
Ex.15 Describe an activity to show that the thermoplastic is a poor conductor of electricity.
Sol. Observe the electrical wires. These wires have plastic covering which show that plastics are poor conductores. The handles of screw dirvers are made of plastics. These obsefvatiions show that thermoplastic is a poor conductor of electricity.
EXERCISE - I
Q.1 What are clothes made up of ?
Q.2 What are fabrics made up of ?
Q.3 What are natural fibres ?
Q.4 Give two examples of natural fibres.
Q.5 What are synthetic fibres ?
Q.6 Name two man-made fibres ?
Q.7 What are polymers ?
Q.8 Name a natural polymer ?
Q.9 Name the fibre having properties similar to that of silk.
Q.10 What is the common name of rayon ?
Q.11 How was rayon is obtained ?
Q.12 Name a man-made fibre which was made without using natural raw materials.
Q.13 What are the raw materials used in making Nylon.
Q.14 Which is the first fully synthetic fibre ?
Q.15 Name two articles made by rayon.
Q.16 Write the names of two articles made by nylon.
Q.17 Name a polymer which is commonly used.
Q.18 What is polyester ?
Q.19 Which is more stronger a wire of steal or a wire of Nylon ?
Q.20 Name a synthetic fibre which works like wool.
Q.21 What are petrochemicals ?
Q.22 What are Plastics ?
Q.23 How many types of arrangement of units in plastics ? Name them.
Q.24 Name two types of plastics.
Q.25 Give two examples of Thermolplastics ?
Q.26 What is the full form of PVC ?
Q.27 Name two Thermosetting plastics ?
Q.28 Why plastics are not ecofriendly ?
Q.29 Why is Polyester quite suitable for making dress materials ?
Q.30 What are the raw materials used in making polyester ?
Q.31 What are the qualities of synthetic fibres which make them more popular than natural fibres.
Q.32 Why should we not wear synthetic clothes while working in kitchen ?
Q.33 Why is it convenient to store plastic containers than metals ?
Q.34 Why are plastic used widely in the industries and household articles ?
Q.35 What are biodegradable and non-biodegradable materials ? Explain with examples.
Q.36 What is 4R principle ?
Q.37 Explain with the help of an activity that nylon thread is stronger than cotton, wool, silk and nylon.
EXERCISE -II
Q.1 South-Indian temples are made of :-
(A) Granite (B) Sandstone
(C) Limestone (D) Concrete
Q.2 Dams on rivers are mostly made by :-
(A) Sandstone
(B) Limestone
(C) Metamorphic rocks
(D) Granite
Q.3 Red Fort at Delhi and palace of Fatehpur Sikri are made of :-
(A) Granite (B) Sandstone
(C) Limestone (D) Concrete
Q.4 Who discovered cement?
(A) Agassiz (B) Albertus Magnus (C) Joseph Aspdin (D) Janseen
Q.5 Which of the following is used to build bridges?
(A) Cinder concrete (B) Sandstone
(C) Limestone (D) None of these
Q.6 Which of the following is used to reinforce cement?
(A) Bricks
(B) Stones
(C) Steel rods or bars
(D) Mortar
Q.7 Photochromic glass contains :-
(A) Silver bromide (B) Silver iodide (C) Silver chloride (D) All of these
Q.8 Which of the following is used in endoscopy?
(A) Optical fibres (B) Glass fibres (C) Glass wool (D) None of these
Q.9 Purple-blue coloured glass is obtained by the addition of :-
(A) Chromium salts (B) Ferrous oxide (C) Cobalt salts (D) None of these
Q.10 Terra cotta is :-
(A) Kaolin
(B) Clay
(C) Unglazed primitive pottery
(D) Porcelain
Q.11 Porcelain is made from :-
(A) Clay (B) Kaolin
(C) Quartz (D) White clay
Q.12 Which of the following is a natural polymer?
(A) Cellulose (B) Nylon
(C) Polythene (D) PVC
Q.13 Which of the following have long-chains of protein?
(A) Jute (B) Cotton
(C) Silk and wool (D) All of these
Q.14 Thermocole is made from
(A) Polythene (B) Polystyrene (C) Perspex (D) Teflon
Q.15 Which of the following is thermoplastics?
(A) Polythene (B) Bakelite
(C) Both of these (D) None of these
Q.16 Contact lenses are made from :-
(A) Polyvinyl chloride (B) Polystyrene (C) Lucite (D) Teflon
Q.17 Which of the following is used as non-stick coating for cooking utensils?
(A) Perspex (B) Styrofoam
(C) Polystyrene (D) Teflon
Q.18 Which of the following are thermosets?
(A) Formica and Melamine
(B) Polystyrene
(C) Polythene
(D) Thermocole
Q.19 Which of the following is similar to cotton?
(A) Nylon (B) Dacron
(C) Rayon (D) Terylene
Q.20 Which of the following do not soften upon heating?
(A) Lucite (B) Bakelite
(C) Polystyrene (D) Polythene
Q.21 Which of the following does not produce insoluble carbonates in hard water?
(A) Soap (B) Detergent
(C) Both of these (D) None of these
Q.22 Which of the following is alkaline in nature?
(A) Soap (B) Detergent
(C) Both of these (D) None of these
Q.23 Which of the following is the basic constituent of Nitrogenous fertilizers?
(A) Amide (B) Ammonia
(C) Sulphuric acid (D) Hydrochloric acid
Q.24 Heptachlor is :-
(A) Fungicide (B) Weedicide
(C) Insecticide (D) All of these
ANSWERS KEY
1. A 2. D 3. B 4. C
5. A 6. C 7. B 8. A
9. C 10. C 11. D 12. A
13. C 14. B 15. A 16. C
17. D 18. A 19. C 20. B
21. B 22. B 23. B 24. C
EXERCISE - III
1. The raw material for the production of synthetic fibres are obtained from ______and ______-
(A) Crude oil, petroleum oil
(B) Rice, Wheat
(C) Crude Oil, Rice (D) None of these
2. Which device is used in textile industry for drawing syntehtic firbe -
(A) Conveyor Belt (B) Cranes (C) Spinneret (D) None of these
3. Nylon, polyester, acrylic are manufactured -
(A) From plants (B) From Petrochemicals (C) From animals (D) None of these
4. The fibre that burns completely leaving no residue
(A) Cotton (B) Acrylic (C) Polyester (D) None of these
5. Which property of cotton makes it suitable for use as clothing material in summer -
(A) It leaves no residue on burning
(B) Its tendency to absorb moisture
(C) Both (a) and (b) (D) None of these
6. The synthetic fibre that resembles wool in its properties is-
(A) Terylene (B) Nylon (C) Acrylic fibres (D) None of these
7. Most synthetic fibres have -
(A) High elasticity
(B) Low elasticity
(C) Moisture observing capacity (D) None of these
8. Which synthetic fibre was discovered first -
(A) Rayon (B) Nylon (C) Polyester (D) None of these
9. This synthetic fibre burns slowly with a smell that of burning hair -
(A) Nylon (B) Wool and Silk (C) Acrylic (D) None of these
10. PVC (Polyvinyl chloride) and polythene are-
(A) Examples of thermoplastic
(B) Examples of thermosetting
(C) Examples of natural substance (D) None of these
11. Which of the following is used in automobile battery casings -
(A) Polystyrene (PS) (B) Poyvinyl chloride (PVC)
(C) Polypropylene (PP) (D) None of these
12. Ropes made of nylon an polyester are commonly used in cranes and elevators because_____
(A) It is inflammable
(B) It is good conductor of heat and electricity
(C) It is Insulator (D) Of their high elasticity and tensile strength
13. An example of thermosetting plastic which is also a poor conductor of heat and electricity-
(A) Polythene (B) Bakelite (C) Polyster (D) None of these
14. My mother always buys PET bottles and PET jars for storing rice and sugar, why ?
(A) Because it is air tight and does not allows germs to enter in
(B) Because it is cheaper
(C) Because it is poor conductor of heat and electricity
(D) None of these
15. -
(A) As it is non biodegradable
(B) As it emits smoke on burning
(C) Both (A) and (B) (D) None of these
16. I understand why a chef never wears polyester clothes while working in the kitchen-
(A) Because they absorb sweat easily
(B) Because synthetic materials catch fire easily
(C) Because they are comfortable to wear (D) None of thesse
17. Plastic containers are preferred over iron container because plastic is -
(A) Non reactive
(B) Easy to handle
(C) Both (A) and (B) (D) None of these
18. Non stick cookware has coating of -
(A) Teflon (B) Melamine (C) PET (D) None of these
19. Which of the following statement is true for Rayon
(A) It is cheaper than wool
(B) It is obtained by chemical treatment
(C) Both (A) and (B) (D) None of these
20. On a rainy day one must avoid wearing clothes made of -
(A) Nylon (B) Cotton (C) Rayon (D) None of these
21. Polyester is made of repeating units of chemical called as -
(A) Ester (B) Cotton (C) Ether (D) None of these
22. Petroleum is the main source of -
(A) Silk (B) Plastic (C) Cotton (D) None of these
23. Photochromic glass contains -
(A) Silver bormide (B) Silver iodide (C) Silver chloride (D) All the above
24. Which of the following is used in endoscopy-
(A) Optical fibres (B) Glass fibres (C) Glass wool (D) None of these
25. Purple-blue coloured glass is obtained by the addition of -
(A) Chromium salts (B) Ferrous oxide (C) Cobalt salts (D) None of the above
26. Terra Cotta is -
(A) Kaolin
(B) Clay
(C) Unglazed primitive pottey (D) Porcelain
27. Which of the following is a natural polymer-
(A) Cellulose (B) Nylon (C) Polythene (D) PVC
28. Which of the following have long-chains of protein
(A) Jute (B) Cotton (C) Silk and wool (D) All the above
29. Thermocole is made from -
(A) Polythene (B) Polystyrene (C) Perspex (D) Teflon
30. Which of the following is thermoplastic -
(A) Polythene (B) Bakelite (C) Both the above (D) None of the above
31. Contacts lenses are made from -
(A) Polyvinyl chloride(B) Polystyrene (C) Lucite (D) Teflon
32. Which of the following are thermosets-
(A) Formica and Melamine
(B) Polystyrene
(C) Polythene (D) Thermocole
33. Which of the following is similar to cotton ?
(A) Nylon (B) Dacron (C) Rayon (D) Terylene
34. Which of the following do not soften upon heating -
(A) Lucite (B) Bakelite (C) Polystyrene (D) Polythene
35. Which of the following does not produce insoluble carbonates in hard water-
(A) Soap (B) Detergents (C) Both the above (D) None of these
36. Which of the following is alkaline in nature -
(A) Soap (B) Detergents (C) Both the above (D) None of these
37. The correct formula of washing soda is -
(A) Na2CO3 (B) Na2CO3.H2O (C) Na2CO3.9H2O (D) Na2CO3.10H2O
38. If tartaric acid is not added in baking powder, the cake will taste bitter due to the presence of -
(A) Sodium hydrogen carbonate
(B) Carbon dioxide
(C) Sodium carbonate (D) All of these
39. Soda-acid fire extinguisher extinguishes the fire
(A) By cutting the supply of air
(B) by removing the combustible substance
(C) By raising the ignition temperatue (D) None of these
40. The simplest formula of bleaching powder is -
(A) Ca(OCl2) (B) CaOCl2 (C) CaOCl2.H2O (D) Ca(OCl2).2H2O
41. The substance which, on treating with chlorine, yields, bleaching powder is-
(A) Quick lime (B) Slaked lime (C) Limestone (D) Gypsum
42. The dead burnt plaster is -
(A) CaSO4. 2H2O (B) CaSO4.H2O (C) CaSO4 (D) 2CaSO4. H2O
Which of the following reaction is known as slaking of lime -
43. (A) CaCO3 ® CaO + CO2
(B) CaO + 2HCl ® CaCl2 + H2O
(C) CaCO3 + H2O ®Ca(OH)2 + CO2 (D) CaO + H2O ® Ca(OH)2
44. Bleaching powder is soluble in cold water giving a milky solution due to-
(A) Available chlorine (B) Lime present in it
(C) Calcium carbonate formation (D) The absorption of carbon dioxide from atmosphere
45. In which of the following pair, both the subtances are chemically same -
(A) Milk of lime and lime water
(B) Dead burnt plaster and gypsum
(C) Alumina and gypsum (D) Gypsum and plaster of Paris
46. Which of the following is not a cement producing state in India -
(A) Rajasthan (B) Goa (C) Orissa (D) Gujarat
47. The raw materials used for the manufacture of Portland cement are -
(A) Gypsum and limestone
(B) Limestone and clay
(C) Alumina, clay and gypsum (D) Gypsum and clay
48. The purpose of adding gypsum of cement is -
(A) to make the mixture more homogeneous (B) to improve the mixture of cement
(C) to make the cement light weight (D) to delay the setting time of cement
49. The finely ground powder of limestone and clay is heated to 1773K in a rotary kiln to produce
(A) concrete
(B) reinforced cement concrete
(C) clinker (D) cullet
50. The average composition of ordinary glass is -
(A) Na2O.CaO.6SiO2
(B) Na2O.2CaO.3SiO2
(C) Na2O.CaO.6SiO2.Cr2O3 (D) Na2O.CaO.PbO.6SiO2
51. The glass used for making laboratory apparatus is -
(A) Pyrex glass (B) Hard glass (C) Soft glass (D) Safety glass
52. The windscreen of cars, aeroplanes, etc. is made up of -
(A) Hard glass (B) Safety glass (C) Lead glass (D) Soda glass
53. Which of the substances is present in the Protochromatic glass -
(A) PbO (B) Cr2O3 (C) Borax (D) Silver bormide
54. Steel is mainly an alloy of iron and -
(A) Chromium (B) Nickel (C) Manganese (D) Carbon
55. If steel is heated bright red hot, and is then cooled slowly, the process is called -
(A) Quenching (B) Annealing (C) Tempering (D) Smelting
56. Sodium is a -
(A) Silver white and very soft metal
(B) Colourless and hard metal
(C) Silvery white and very hard metal (D) Colourless and very soft metal
57. Which of the following is a basic oxide -
(A) CaO (B) CO2 (C) H2O (D) N2O
58. Which of the following is a good conductor electricity-
(A) Charcoal (B) Coke (C) Graphite (D) Diamond
59. Which of the following is used for making magnets
(A) Duralimin (B) Magnalium (C) Bronze (D) Alnico
60. Iron burns in air to form -
(A) FeO (B) Fe2O3 (C) Fe3O4 (D) FeO2
61. When a small piece of dry sodium is put in water, it react vigorously to produce -
(A) Nitrogen gas
(B) Hydrogen gas
(C) Carbon dioxide gas (D) Sulphur dioxide
62. What should be added to pure iron to make stainless steel -
(A) Nickel and cobalt (B) Cadmium and Chromium
(C) Nickel and Cadmium (D) Chromium and Nickel
63. The valency of mercurous ion is -
(A) Two (B) One (C) Three (D) Four
64. Oridinary glass is mixture of -
(A) Sodium silicate, Calcium silicate
(B) Sodium silicate, Calcium silicate and Silica
(C) Sodium silicate and Silica (D) None of the above
65. Glass used for making wind screens of automobiles is -
(A) hard glass (B) Photo chromatic glass (C) Safety glass (D) Optical glass
66. Annealing is done to -
(A) Increase brittleness
(B) Increase Transparency
(C) Decrease brittleness
(D) Increase refractive inedex
67. Sodium chloride is added to the solution after Saponfication to cause the -
(A) Hydrolysis of soap (B) Precipitation of soap
(C) Sedimentation of soap
(D) None of these
68. The automatic darkening of photo chromatic glass is because of the presence of -
(A) Silver bromide (B) Silicon iodide
(C) Silicon dioxide (D) Lead oxide
69. Which of the following is not a man made polymer-
(A) Nylon (B) Polyethene
(C) Teflon (D) Wool
70. Polymer used in making floor tile is -
(A) Teflon (B) Polypropylene
(C) Polyvinylchloride (D) buta-1,3-diene
71. Which of the following is an example of condensation polymers-
(A) Polyethene (B) Neoprene
(C) Teflon (D) Nylon
72. The hydrophilic end of synthetic detergent is
(A) CH3(CH3)10–CH2 (B) –CH3
(C) SO3–, Na+ (D) –COO–Na+
73. Which of the following are biodegradable -
(A) Soaps (B) Manure
(C) Polyethene (D) Teflon
74. The main constituents of cement are :-
(A) Calcium oxide, Silicon dioxide, Aluminium oxide
(B) Calcium oxide, Iron oxide, Sulphur dioxide
(C) Magnesium oxide, Silicon dioxide, Aluminium
(D) None of these
75. Hard glass is prepared by :-
(A) Fusing a mixture of sodium carbonate, calcium carbonate and silica
(B) Fusing a mixture of potassium carbonate, calcium carbonate and silica
(C) Fusing a mixture of potassium carbonate and any oxide
(D) None of the above
76. Flint glass or optical glass contains :-
(A) Lead oxide (B) Manganese dioxide (C) Lead dioxide (D) Cobalt chloride
77. The main raw materials required for the manufacture of portland cement are :-
(A) Limestone and clay (B) Limestone and gypsum
(C) Limestone and calcium chloride (D) Limestone and silica
78. Gypsum is added to cement because :-
(A) It makes the cement very hard
(B) It increases the pace of setting of cement
(C) It slows down the initial setting of cement when water is added
(D) None of the above
79. A thick paste of cement, sand and water is called
(A) Concrete (B) Mortar (C) Slurry (D) Moderator
80. A mixture of cement, gravel, coarse sand and water is called :-
(A) Mortar (B) Concrete (C) Slurry (D) Hardner
81. RCC is :-
(A) The concrete having an iron framework inside it as a support
(B) The crushed cement in which more gravel is added
(C) Prepared by adding calcium chloride to the limestone and calcium silicate
(D) None of the above
82. The process of making soap by the hydrolysis of fats and oils with alkalis is called :-
(A) Hydrolysis (B) Saponification (C) Esterification (D) None of the above
83. The soap can be hardened by :-
(A) Adding sodium carbonte or sodium silicate during its manufacture
(B) Adding sodium chloride
(C) Adding potassium hydroxide
(D) Adding animal fat and coconut oil
84. The plastics which soften upon being heated but regains all its original properties on cooling are known as
(A) Thermoplastics (B) Thermosetting plastics (C) Thermoelastic (D) Cellulose
85. Natural rubber is a polymer of
(A) butadiene (B) chloroprene (C) 2,3-dimethylbutadiene (D) isoprene
86. If natural rubber is treated with sulphur its properties are markedly changed. The process is called
(A) catenation (B) isomerization (C) polymerization (D) vulcanization
87. Synthetic rubber, neoprene is prepared by the polymerization of
(A) butadiene (B) chloroprene (C) 2,3-dimethylbutadiene (D) isoprene
88. Thiokol is a -
(A) Fibre (B) plastic (C) rubber (D) detergent
89. Which of the following is not true for synthetic detergents ?
(A) Synthetic detegents are chemically different from ordinary soaps
(B) Synthetic detergents do not form any insoluble compound with calcium or magnesium
(C) All synthetic detergents are bio-degradable
(D) Raw materials for preparing synthetic detergents are obtained from petroleum industry.
90. Soaps are sodium salts of fatty acids. Which of the following fatty acid does not form soap
(A) Butyric acid (B) Oleic acid (C) Palmitic acid (D) Stearic acid
91. Which of the following is a detergent ?
(A) C8H17SO3–Na+ (B) C9H17SO3–Na+ (C) C12H25SO3–Na+ (D) C12H25COO–Na+
92. Which of the following cannot be used as raw material for the manufacture of soap
(A) Cottonseed oil (B) Lineseed oil (C) Diesel oil (D) Soyabean oil
ANSWERS KEY
1. A 2. C 3. B 4. A
5. B 6. C 7. A 8. A
9. B 10. A 11. C 12. D
13. B 14. A 15. C 16. B
17. C 18. A 19. C 20. B
21. A 22. B 23. D 24. A
25. C 26. C 27. C 28. C
29. B 30. A 31. C 32. A
33. C 34. B 35. B 36. B
37. D 38. C 39. A 40. B
41. B 42. C 43. B 44. B
45. A 46. B 47. B 48. D
49. C 50. A 51. A 52. B
53. D 54. D 55. B 56. A
57. A 58. C 59. D 60. B
61. B 62. D 63. B 64. B
65. A 66. C 67. B 68. A
69. D 70. C 71. D 72. D
73. A 74. A 75. B 76. A
77. A 78. C 79. B 80. B
81. A 82. B 83. B 84. A
85. D 86. D 87. B 88. C
89. C 90. A 91. C 92. C