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Plastics - class-XI

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Which of the following is not a characteristic of thermosetting polymers?

  1. Linear or slightly branched long chain polymers.

  2. Heavily branched and cross-linked polymers.

  3. Become infusible on moulding.

  4. Cannot be remoulded or reused on heating.


Correct Option: A
Explanation:

Some characters of thermosetting polymers:

  • these polymers are cross-linked or heavily branched molecules,
  • on heating it undergoes extensive cross-linking in moulds and again become infusible,
  • these cannot be reused
    Some common examples are bakelite, melamine and urea formaldehyde resin

Which among the following is a cross-linked polymer?

  1. Polyesters

  2. Glycogens

  3. Melamine-formaldehyde

  4. Polyvinyl chloride


Correct Option: C
Explanation:

Melamine-formaldehyde polymer is cross-linked polymer or thermosetting polymer which on heating undergo extensive cross linking in moulds and again become infusible. These cannot be reused. Some common examples are bakelite, urea-formaldelyde resins, etc.

The correct option is [C].

Which of the following polymers does not involve cross-linkages?

  1. Vulcanised rubber

  2. Bakelite

  3. Melamine

  4. Teflon


Correct Option: D
Explanation:

Bakelite, melamine( thermosetting) and vulcanised rubber( elastomer) have cross-linkages in the structures whereas Teflon is linear addition or chain growth polymers that have not cross-linkages.

the correct option is [D].

Match the column I with column II and mark the appropriate choice.

Column I Column II
(A) Buna-S (i) Thermosetting
(B) Polyamides (ii) Fibres
(C) Polyvinyls (iii) Elastomers
(D) Urea-formaldehyde (iv) Thermoplastics
  1. (A) $\rightarrow$ (iv), (B) $\rightarrow$ (iii), (C) $\rightarrow$ (i), (D) $\rightarrow$ (ii)

  2. (A) $\rightarrow$ (ii), (B) $\rightarrow$ (i), (C) $\rightarrow$ (iii), (D) $\rightarrow$ (iv)

  3. (A) $\rightarrow$ (iii), (B) $\rightarrow$ (ii), (C) $\rightarrow$ (iv), (D) $\rightarrow$ (i)

  4. (A) $\rightarrow$ (i), (B) $\rightarrow$ (iv), (C) $\rightarrow$ (ii), (D) $\rightarrow$ (iii)


Correct Option: C
Explanation:
 Buna$-S$  (iii) Elastomers
 Polyamides  (ii) Fibers
 Polyvinyls (iv) Thermoplastic
 Urea-formaldehyde (i) Thermosetting

[A] Elastomers - these are rubber like solids with elastic properties

[B] Fibers - these are thread forming solids which possess high tensile strength and high modulus,
[C] Thermoplastic - these are linear or slightly branched long chain molecules capable of repeatedly softening on heating and hardening on cooling,
[D] Thermosetting polymers are cross-linked and heavily branched molecules which on heating undergo extensive cross-linking in moulds and again become infusible.
The correct option is $[C]$.

Teflon is a special plastic on which oil and water do not stick.

  1. True

  2. False


Correct Option: A
Explanation:

Teflon is a synthetic polymer (polytetrafluoroethylene) that can be used to cover the surface of certain object and imparts nonstick properties to it. Teflon is used for Non Stick material because the monomer units are hydrophobic in nature (tetrafluoroethylene) and thus oil and water do not stick to it.
option A is correct.

Cooking pans have plastic handles.

  1. True

  2. False


Correct Option: A
Explanation:

Plastics are categorized into thermosoftening/thermoplastic and thermosetting/thermoset plastics.
In thermosoftening plastics, the forces between the polymer chains are weak, so they can easily be remoulded into new shapes. This makes it possible to recycle this type of plastic. whereas in thermosetting plastics there are strong covalent bonds forming cross-links between the polymer chains, making these plastics hard and rigid. Once set into its original shape, a thermosetting plastic can't be softened and remoulded. The strong bonds between polymers also mean that thermosetting plastics are much more heat resistant than thermosoftening ones.
Cooking pans' handle are made from thermosetting plastic like bakelite as this is resistant to heat.
option A is correct

Plastics are generally good conductors of electricity.

  1. True

  2. False


Correct Option: B
Explanation:

Plastics are high molecular weight (macromolecular or polymeric) organic substances that have usually been synthesized from low molecular weight compounds. Being organic origin have no ionic character in them and thus can not conduct electricity. They are insulators.
Hence, option $B$ is correct.

Plastics are mainly used by everyone because :

  1. They are cheap

  2. Easy to handle

  3. Do not break

  4. Light weight


Correct Option: A,B,D
Explanation:

Plastics find many applications in day-to-day life because of various reasons as :


1) They are economical, thus are cheap.
2) Easy to handle unlike ceramics and glass which are brittle.
3) Light weight materials and easy to carry.
4) High durability but they are breakable.

Therefore option A, B and D are correct.

Plastic containers can resist decomposition for:

  1. 50000

  2. 3000

  3. 1000

  4. 40000


Correct Option: C
Explanation:

Plastic waste is one of many types of wastes that take too long to decompose. Normally, plastic items can take up to 1000 years to decompose in landfills. But plastic bags we use in our everyday life take 10-1000 years to decompose, while plastic bottles can take 450 years or more.

Which of the following takes so many years to degrade?

  1. Jute

  2. Cotton

  3. Wool

  4. Plastic


Correct Option: D
Explanation:
Non-biodegradable materials are not degraded by natural factors such as micro-organisms such as bacteria, UV radiations etc. They stay longer and difficult to degrade.
Jute, cotton and wool are made from natural fibre and are therefore biodegradable while plastic is a synthetic polymer and is non-biodegradable waste.
option D isc orrect

We come to a conclusion, that plastics are bad conductors of electricity from the followings:

  1. Refrigerators and freezers have a plastic foam core.

  2. Electrical wires have a plastic covering.

  3. Cooking pans have plastic handles.

  4. It is used to prepare parachutes.


Correct Option: B

Which of the following substance is bio-degradable?

  1. cloth

  2. thermosetting plastic

  3. thermoplastic

  4. PVC pipes


Correct Option: A
Explanation:
Biodegradable wastes are such waste materials which are and can be degraded by natural factors like microbes (e.g. bacteria, fungi and few more), abiotic elements like temperature, UV, oxygen, etc. Example: kitchen wastes and other natural wastes. Cloth is a natural polymer made from cellulose, cotton, silk, wool etc and is biodegradable while plastics (thermoplastic, thermosetting plastics, PVC) are synthetic polymers and are non-biodegradable
option A is correct

These processes can be used to prevent health hazards of plastics :

  1. Reduce

  2. Reuse

  3. Recover

  4. Recycle


Correct Option: A,B,C,D
Explanation:

 

A number of waste prevention techniques are available, and they are commonly summarized as the so-called 4Rs: reduction, reuse, recycling and recovery. 

Reduction, reuse and recycling are known in the industry as the 3Rs. 

We must reduce the use of resources as much as possible and save them for the future generation. Reducing usage is a method of conservation of resources.

Therefore, A, B, C and D option are correct.

Burning of plastic causes:

  1. water pollution

  2. air pollution

  3. sound pollution

  4. All of these


Correct Option: B
Explanation:

Burning of plastic produces carbon dioxide which causes heavy air pollution. 

Like synthetic fibres, plastic is also a:

  1. polymer

  2. polythene

  3. polycot

  4. acrylic


Correct Option: A

What are the two types of arrangement in plastics ?

  1. Linear, Horizontal

  2. Horizontal, Cross-linked

  3. Linear, Cross-linked

  4. Linear, Vertical


Correct Option: C

Which of the following statement is true about PVC (polyvinyl chloride) and polythene?

  1. They are thermoplastics

  2. They are thermosetting plastics

  3. They are examples of natural substances

  4. They are natural fibres


Correct Option: A
Explanation:

Thermoplastics on heating get deformed (its shape and size can be altered) and thus can also be bent. On the other hand, thermosetting plastics cannot be bent once moulded. Some examples of Thermoplastics are – Polythene and PVC. Some examples of Thermosetting plastics are – Bakelite and Melamine.


Hence, the correct option is $\text{A}$

A material which is not easily decomposed by natural processes is termed as :

  1. biodegradable material

  2. non-biodegradable material

  3. recycled material

  4. natural material


Correct Option: B
Explanation:

A material which is not easily decomposed by natural processes is termed as $\text {non-biodegradable material}$. Examples are polyethene, PVC, PS. It takes many years for decomposition. Hence, option B is correct.

Which of the following are uses of plastics in health care industry?

  1. Packaging of tablets

  2. Stitching wounds

  3. Syringes

  4. All of the above


Correct Option: D
Explanation:

Plastics in health care industry are used in packaging of medicines;plastic threads are used for stitching wounds. Also syringes, gloves and many kind of medical instruments are made up of plastic.

Why plastic containers are favoured for storing food?

  1. Plastics are light in weight

  2. Plastic is a strong and durable material 

  3. Plastics are easy to handle

  4. All of the above


Correct Option: D
Explanation:

Plastics are used to store food because:
(i) Plastics are light in weight.
(ii) Plastic is a strong and durable material and
(iii) plastics are easy to handle.

Telephone instruments, plastic toys, ball point pens, plastic bowls are examples of:
  1. Thermoplastics

  2. Thermosetting plastic

  3. Polyester

  4. None of the above


Correct Option: A
Explanation:

 Telephone instruments, plastic toys, ball point pens, plastic bowls  are thermoplastics and so can be recycled.
Cooker handles, carry bags, plastic covering on electric wire, plastic chains etc are thermosetting plastics and so cannot be recycled.

Plastics are ________ water and therefore are used in making buckets.
  1. lighter than

  2. soluble in

  3. insoluble in

  4. none of these


Correct Option: C

Like synthetic fibres, plastic is also a :

  1. polymer

  2. polyester

  3. natural

  4. None of the above


Correct Option: A
Explanation:

Plastic is also a polymer like the synthetic fibre. It is the chain of small units joined together.

Most of the thermoplastic :

  1. can be recycled

  2. cannot be recycled

  3. cannot be heated

  4. none of the above


Correct Option: A
Explanation:

A thermoplastic is the material which become soft on heating and hard on cooling several times.
Therefore, they can be recycled.

Containers which are light weight, lower price, good strength and easy to handle is made up of :

  1. Plastic

  2. Metal

  3. Wood

  4. Brick


Correct Option: A
Explanation:

Plastic has light weight, lower price, good strength and easy to handle. Therefore, container are made from plastic.

Which plastic is commonly used as carry bags?

  1. Polythene

  2. Polyester

  3. PET

  4. Acrylic


Correct Option: A
Explanation:

Polyethylene is a thermoplastic polymer consisting of long hydrocarbon chains. Polyethylene or polythene is the most common plastic. Its primary use is in packaging (plastic bag, plastic films, containers including bottles, etc.).

Plastic is a polymer consisting of:

  1. synthetic monomers

  2. semi-synthetic monomers

  3. natural monomers

  4. both a and b


Correct Option: D
Explanation:

Plastic is a material consisting of synthetic or semi-synthetic organics that can be moulded into solid objects of diverse shapes. Plastics are typically organic polymers of high molecular mass, but they often contain other substances. They are usually synthetic, most commonly derived from petrochemicals, but many are partially natural.

Which plastic is called a fire proof plastic?

  1. Melamine

  2. Bakelite

  3. Teflon

  4. Acrylic


Correct Option: A
Explanation:

Melamine is poor conductor of heat and resists fire. Most of the synthetic fibres are poor conductors of heat and electricity. However, melamine is used as a coating on the uniforms of firemen as they are flame resistant.

Which of the following statement is true about thermosetting plastic?

  1. It undergoes irreversible change during curing

  2. It can melt and take shape only once

  3. It cannot be recycled

  4. All of above


Correct Option: D
Explanation:

Thermosetting plastics contain polymers that cross-link together during the curing process to form an irreversible chemical bond. It can't be recycled. The cross-linking process eliminates the risk of the product remelting when heat is applied, making thermosetting ideal for high-heat applications such as electronics and appliances.

Why is plastic used in covering of electrical appliances?

  1. Good conductors of heat and electricity

  2. Durable

  3. Poor conductors of heat and electricity

  4. None of above


Correct Option: C
Explanation:

Plastic is a poor conductor of heat and electricity. 


This makes it suitable to make the covering of electric wires, handles of electrical appliances, handles of utensils, kitchenware, floor tiles, etc.

Hence the correct option is C.

Plastic can be used as :

  1. insulator

  2. conductor

  3. Both A and B

  4. None of above


Correct Option: A
Explanation:

Most plastics are both thermal and electrical insulators, meaning they show high resistance to electrical current and are poor conductors of heat.

Thermosetting polymer such as bakelite are used as electrical insulators.

Handles of most pans are made up of:

  1. thermoplastic

  2. thermosetting plastic

  3. acrylic

  4. hemp


Correct Option: B
Explanation:

Handles of most pans are made up of thermosetting plastic. Thermosetting plastic does not melt easily. These plastic cannot be reshaped again and again.

The world's first fully synthetic plastic was:

  1. Polystyrene

  2. Nylon

  3. Bakelite

  4. Teflon


Correct Option: C
Explanation:

The world's first fully synthetic plastic was bakelite, invented in New York in 1907 by Leo Baekeland who coined the term 'plastics'. Bakelite is made from carbolic acid (phenol) and formaldehyde and is referred to as a phenolic resin. Bakelite was the first thermosetting plastic.


Hence, the correct option is $C$

Which of the following are the advantages of plastic over metals?
1. Plastics are lighter.
2. Plastics are usually cheaper.
3. Plastics are inert to both acids and alkalis.

  1. (1) and (2) only

  2. (1) and (3) only

  3. (2) and (3) only

  4. (1) ,(2) and (3)


Correct Option: D
Explanation:
With the increased knowledge of plastics and the improved capabilities of machining equipment, the industry is now capable of producing plastic components to the same exacting standards as metallic components.
Plastics can  provide the benefit of reduced weight. This is crucial for a manufacturer of aircraft parts, for instance, decreased weight means increased fuel efficiency. This has lead to manufacturers transitioning from aluminum and steel to plastic and composites.
Plastic are less sensitive to weather than metal, resisting corrosion and rust. In addition, additives can be introduced to protect the pieces from damaging UV rays.
Plastics are resistance to many more chemical compounds like acids and alkalis. This opens up the options for use in solution tanks.
Plastics can be designed for resist impact and dents, making it durable, strong, and stable.
Plastics have tighter tolerances.

Nylon is obtained by:

  1. treating wood pulp

  2. solidifying water

  3. mixing coal, air and water

  4. mixing chemicals


Correct Option: C
Explanation:

Nylon was first commercially synthesized fibre. The production of nylon was started almost simultaneously in New York and London, thus it got its name (NY for New York and Lon for London) as nylon. Nylon is synthesized from coal, water and air. Fibre of nylon is very strong and it also resembles silk.

Bakelite is an example of ___.

  1. elastomer

  2. fibre

  3. thermoplastic

  4. thermosetting polymer


Correct Option: D
Explanation:

A thermosetting plastic, also known as a thermoset, is a polymer material that irreversibly cures. The cure may be induced by heat, generally above $200^o C$ $(392\ F)$, through a chemical reaction or a suitable irradiation.
$Bakelite$ is one example of this type.

State True or False :

Most of the plastics are biodegradable.

  1. True

  2. False


Correct Option: B
Explanation:

Most of the plastics are non-biodegradable.


Hence the given statement is false.

Polystyrene and PVC are thermoplastics.

  1. True

  2. False


Correct Option: A
Explanation:

Polymer of styrene and vinyl chloride (polystyrene and PVC)  can be repeatedly melted and re-molded into new products and are 100% recyclable


Therefore they are examples of thermoplastic. Other examples of thermoplastics include polythene (PE), polypropylene (PP), nylons, etc.

Therefore, option A is correct.

Which of the following will be suitable for coating dress materials of fire - men ?

  1. Nylon

  2. Polyster

  3. Melamine

  4. Acrylic


Correct Option: C
Explanation:

Melamine have properties to interfere with the combustion in many different ways. Moreover, it can withstand high temperature, it is corrosion resistant and easy to handle.

Consider the following statements-


I. weakest intermolecular forces are present in elastomers.

II. Fibers possess a crystalline nature.


III. Ionic bonds are present in thermoplastic polymers.

Select the correct option from the following:
  1. I and II

  2. II and III

  3. I and III

  4. I,II and III


Correct Option: A
Explanation:
Elastomers are rubber like solid polymers in which polymer chains are hold together by weakest intermolecular forces.
Eg : Natural rubber
Fibers are thread-like polymers & can be woven into fabrics. They possess high tensile strength & are crystalline in nature.
Eg ; Nylon $6,6$.

Hence, the correct option is A.

Thermosetting plastics cannot be softened by heating because:

  1. they are cross linked polymers with hydrogen bonds b/w each other.

  2. they are linear chains of polymers

  3. they are large cross-linked molecules with strong covalent bonds b/w the atoms along each chains

  4. they are large cross-linked molecules with strong electrovalent bonds between the atom along each chain.


Correct Option: A
Explanation:

Thermosetting polymers are formed from monomers of viscous state which changes irreversibly on heating into an infusible insoluble polymer. They have high crosslinks due to which they are rigid.

Which of the following properties of plastic make it most convenient to use?

  1. It is non-reactive

  2. Light, strong and durable

  3. Easily remouldable

  4. All of the above


Correct Option: D
Explanation:

Plastics are non-reactive at room temperature and others are highly reactive.

Because of lower density than metals, plastic is light, strong and durable so can be molded in different shapes and sizes easily.
So all the options are correct, all are properties of plastic.

Option D is correct answer.

Which one among the following is a thermosetting plastic?

  1. PVC

  2. PVA

  3. Bakelite

  4. Perspex


Correct Option: C
Explanation:
Bakelite is another name of phenol formaldehyde which is a thermosetting plastic so bakelite is a thermosetting plastic.

Plastic which has cross-linked (3D) structure and is generally made by the condensation polymerization method is called thermosetting plastic. It can't be reused once it is processed.

Which of the following is not correct regarding terylene ?

  1. Condensation polymer

  2. Synthetic fibre

  3. Step-growth polymer

  4. Known as dacron

  5. Thermosetting plastic


Correct Option: E
Explanation:

Terylene is a synthetic polymer formed by the condensation polymerization reaction of terephthalic acid and ethylene glycol with the release of a methanol molecule. 


It forms by a step-growth polymerization mechanism in which a bi-functional or multifunctional monomer react to form the first dimer, then trimer, longer oligomer and eventually long-chain polymers. 

It is also called as Dacron and is a thermoplastic, which can be remelted time and again without producing any change.

Which of the following is NOT true?

  1. Thermosetting plastic are bad conductors of heat and electricity.

  2. Thermoplastics are good conductor of heat and electricity.

  3. Plastic do not get corroded easily.

  4. Plastic is also a polymer.


Correct Option: B
Explanation:

Thermoplastic polymer can change their properties when heated and cooled. All plastics are bad conductors of heat and electricity.


Option B is correct.

Which of the following is a property of plastic?

  1. Flame resistant

  2. Non-corrosive

  3. Mouldable

  4. All of the above


Correct Option: D
Explanation:

The properties of the plastics are as follow:

  • They can be easily molded.
  • They are non-corrosive.
  • They are flame resistant.
  • They are a bad conductor of electricity.
Thus all the properties that are given in the options are properties of plastic.

Coating of melamine plastic is used as :

  1. good conductor of heat

  2. strong and durable

  3. fire proofplastic

  4. plastic cook ware


Correct Option: C

Plastics which when moulded once, cannot be softened by heating are called :

  1. thermosetting plastics

  2. thermoplastics

  3. thermostat plastics

  4. mould plastics


Correct Option: A

Which material is used for making:
(i) Saucepan handles
(ii) Electric plugs/switches/plugboards

  1. Bakelite

  2. PVC

  3. Polythene

  4. Polyester


Correct Option: A
Explanation:

(i) Saucspan handles are made of bakelite as it is a bad conductor of heat.
(ii) 
Bakelite is also a bad conductor of electricity so the electric plugs, switches, etc. are made of it.

What characteristic property of plastic makes it useful in making containers for storing food items?

  1. They do not react with food stored in them

  2. They are poor conductors of electricity

  3. They are light weight and strong

  4. They are non-degradable.


Correct Option: A,C
Explanation:

Since plastics do not react with water and air, they are noncorrosive in nature and are thus used for storage.

An example of thermosetting plastic, which is also a poor conductor of electricity, is:

  1. polythene

  2. bakelite

  3. polyester

  4. PVC


Correct Option: B
Explanation:

Bakelite is an example of thermosetting plastic which is also a poor conductor of electricity. Due to its insulating character, it is used for switches and other electrical insulators.
Option B is correct.


State True or False.

Plastics are resistant to corrosion.

  1. True

  2. False


Correct Option: A
Explanation:

The given statement is true. Plastics are resistant to corrosion and chemicals.

Statement: The articles made of thermoplastics can be recycled whereas the articles made of thermosetting plastics cannot be recycled.


State whether the given statement is true or false.

  1. True

  2. False


Correct Option: A
Explanation:
The intermolecular forces in thermoplastics are weaker while the intermolecular forces in thermosetting plastics are stronger. The thermosetting plastics cannot be moulded on heating. Thus the articles made of thermoplastics can be recycled whereas the articles made of thermosetting plastics cannot be recycled.

Hence, the given statement is $\text{true}$

A person has to make electric switches and plugs. Which material is recommended ?

  1. Teflon

  2. Bakelite

  3. Rayon

  4. PVC


Correct Option: B
Explanation:
Bakelite has high heat resistant property which makes it a poor conductor of heat and electricity.it is used for making electrical switches because it high heat resistance property protects us from electric shocks.
also it is used to make handles of cooking utensils because of this property it does not conduct heat and so the handles are prevented from becoming too hot and this makes it easy to handle the handles of cooking utensils.

Hence, the correct option is $\text{B}$

Match the column A and B

Column A Column B
(i) Thermoplastics (a) Handles of utensils, floor tiles
(ii) Thermosetting plastics (b) Melamine
(iii) Biodegradable (c) Teflon
(iv) Fire proof plastic (d) Wood
(v) Oil and water do not stick (e) Combs, containers
  1. i-d, ii-e, iii-a, iv-b, v-c

  2. i-e, ii-a, iii-d, iv-b, v-c

  3. i-a, ii-d, iii-b, iv-c, v-e

  4. i-c, ii-b, iii-a, iv-e, v-d


Correct Option: B
Explanation:
Thermoplastic materials are those materials that are made of polymers linked by intermolecular interactions or van der Waals forces, forming linear or branched structures.

Melamine is a versatile material. It resists fire and can tolerate heat better than other plastics. It is used for making fire-resistive uniforms, floor tiles, kitchenware and fabrics which resist fire. 

Thermosetting plastics are generally strong and resistant to heat, but they melt the first time they are heated to a high enough temperature and harden (set) permanently when cooled. They can never be melted or reshaped again. 

They are used in situations where resistance to heat is important, e.g. on kitchen work surfaces, good-quality plastic cups, saucepan handles and plug casings. Wood is biodegradable

Thermoplastics are:

  1. linear polymers.

  2. soften or melt on heating

  3. molten polymer can be moulded in desired shape.

  4. All of these


Correct Option: D
Explanation:

Thermoplastics are linear polymers. They are also known as thermosoftening plastics because they become malleable when heated. Although they are pliable above a certain heat threshold, they return to a solid once they have been sufficiently cooled. For this reason, thermoplastics are put to unique uses in a number of manufacturing and engineering industries.

Apart from their primary characteristics, thermoplastics vary slightly in usage and properties. For example, polystyrene is a hard, water-resistant thermoplastic, according to BBC. This makes it an excellent choice for creating toy models and for packaging that will not be exposed to extreme heat sources in transit. Polymethyl methacrylate is also a stiff thermoplastic, but it is also an electrical insulator and can be polished well, so it is often used in vehicle windows and light covers.

Which of the following is a thermosetting plastic?

  1. PVC

  2. Polyethylene

  3. Bakelite

  4. Terylene


Correct Option: C

Which of the following is used to make disposable cups?

  1. Low density polyethylene

  2. Polypropylene

  3. Polystyrene

  4. PVC


Correct Option: C
Explanation:

Disposable cups are made up of thermocol. It is a synthetic petroleum product which is made by restructuring of the chemical bonding of the polystyrene, to develop a stretch polystyrene. In this process, thermoplastic granules are expanded through the application of steam and air. The expanded granules become large and light in weight.

Thermosetting plastics can be remoulded on gentle heating.

  1. True

  2. False


Correct Option: B
Explanation:

Thermosetting plastics: Which on heating becomes infusible these cannot be reused.Ex- Bakelite,urea formaldehyde resin.

Thermoplastic plastics: These become soft on heating and hard on cooling.
Ex.polythere,polystyrene.
Thermoplastic plastics can be remoulded.

Synthetic fibers are obtained from which of the following?

  1. Plants

  2. Sheeps

  3. Chemicals

  4. Jute


Correct Option: C
Explanation:

Synthetic fibres are created by extruding fibre forming materials through spinnerets into air and water, forming a thread. These artificially manufactured fibres were made from polymers obtained from petro chemicals. These fibres are called synthetic or artificial fibres. The two most common ones are nylon and polyester. Nylon is made from two chemicals, adipic acid (AA) and hexamethylene diamine (HMD).

Therefore, the correct answer is option C.

State true or false.


Most of the plastics are resistant to strong acids and alkalies.

  1. True

  2. False


Correct Option: A
Explanation:

Plastics are not chemically reactive and they are non-corrosive. So, most of the plastics are resistant to strong acids and alkalies. Hence the given statement is True.

Which of the following is considered the first thermoplastic?

  1. PVC

  2. Polystyrene

  3. Melamine

  4. Celluloid


Correct Option: D
Explanation:

Celluloid, which is considered the first thermoplastic, made its appearance in the mid- 1800 s and reigned in the industry for approximately 100 years. During its peak production, it was used as a substitute for ivory. Today, it is used to make guitar picks.

Which of the following is a thermosetting process?

  1. Vulcanization of rubber

  2. Polythene extrusion

  3. Injection molding of PVC

  4. None of above


Correct Option: A
Explanation:

Vulcanization is a chemical process for converting natural rubber or related polymers into more durable materials via the addition of sulphur or other equivalent curatives or accelerators. Cross-linking introduced by vulcanization prevents the polymer chains from moving independently. As a result, when stress is applied the vulcanized rubber deforms, but upon release of the stress it reverts to its original shape.

State true or false.


Nylon is a thermosetting plastic.

  1. True

  2. False


Correct Option: B
Explanation:
Thermoplastics are the polymers which loses their shape on heating and regain their shape on cooling.
Examples: Nylon, PVC, polystyrene, etc.
On the opposite of that Thermosetting doesn't regain its shape after heating.
Nylon is a thermoplastic polymer. Hence the given statement is false.

Which of the following example is not a thermoset plastic?

  1. Epoxy resin

  2. Melamine

  3. Urea formaldehyde

  4. Polyamide


Correct Option: D

Which among the following is a poor conductor of heat and electricity?

  1. Melamine

  2. Bakelite

  3. Both A and B

  4. None of above


Correct Option: C
Explanation:

Bakelite is a thermosetting plastic which is one of the first plastic made from synthetic components. Bakelite was used for its electrical non-conductivity and heat-resistant properties in electrical insulators, radio, and telephone casings.

Similarly, Melamine resin is a thermosetting plastic used in high pressure decorative laminates, laminate floorings and dry erase boards.

_______ provides good heat and sound insulation.

  1. Propylene

  2. Styrofoam

  3. Polythene

  4. Acrylic


Correct Option: B
Explanation:

Polystyrene foam also known as Styrofoam is brittle in tension, lightweight, with good heat and sound insulation. It is available in blocks and used for product-modelling.

Define plasticity :

  1. Ability to regain its original shape.

  2. Ability to flow when subjected to stress.

  3. Ability to change shape permanently.

  4. Both b and c.


Correct Option: D
Explanation:

Plasticity,  ability of certain solids to flow or to change shape permanently when subjected to stresses of intermediate magnitude between those producing temporary deformation, or elastic behaviour, and those causing failure of the material, or rupture.

 Plasticity enables a solid under the action of external forces to undergo permanent deformation without rupture.

Plastics are ____________ in water.

  1. highly soluble

  2. slightly soluble

  3. insoluble

  4. sparingly soluble


Correct Option: C
Explanation:

Plastics are insoluble in water and it cannot be dissolved in water.

This is because of the non-polar nature of the plastic.

When plastics are burnt toxic substances are released into air causing ___________ pollution.

  1. water

  2. air

  3. soil

  4. None of these


Correct Option: B
Explanation:

When plastics are burnt toxic substances are released into $air$ causing air pollution. The sentence is self-explanatory.

We come to a conclusion, that plastics are bad conductors of electricity from the following.

  1. Refrigerators and freezers have a plastic foam core

  2. Electrical wires have a plastic covering

  3. Cooking pans have plastic handles

  4. We use to prepare parachutes


Correct Option: A,B,C
Explanation:

Most of the commonly used household electronics like freezers, washing machine, etc are made of plastic since it is the bad conductor of electricity.

Which of the following is/are reasons of using plastics?
1.They are transparent.
2. They are cheap.
3. They can be moulded into diffrent shapes.

  1. (1) only

  2. (2) only

  3. (1) and (3) only

  4. (2) and (3) only


Correct Option: D
Explanation:
All three are correct. But the reason for their vast use is the less expenditure and re-usability. 
With the increased knowledge of plastics and the improved capabilities of machining equipment, the industry is now capable of producing plastic components to the same exacting standards as metallic components.
Plastics are cheaper than metals.  They are transparent and elastic material that could be molded when heated. Plastics are easy to reuse as they can be molded into different shapes can be designed for resist impact and dents, making it durable, strong, and stable.


Fibre obtained by chemical treatment of wood pulp is called:

  1. natural Silk

  2. rayon

  3. nylon

  4. polyster


Correct Option: B
Explanation:
Natural Silk: The protein fibre of silk is composed mainly of fibroin and is produced by certain insect larvae to form cocoons.
Rayon: Rayon is a manufactured regenerated cellulose fibre. It is made from purified cellulose, primarily from wood pulp, which is chemically converted into a soluble compound.
Nylon: Nylon is a strong, light synthetic fibre. Nylon thread is made from the polymerization of an amine and an acid chloride. 
Polyester: Polyester is a synthetic polymer made of purified terephthalic acid or its dimethyl ester dimethyl terephthalate and mono ethylene glycol. 

Hence, the correct option is $B$

Which is NOT the general characteristics of plastics?

  1. Good electrical insulators

  2. Acceptable acoustic insulation

  3. Resistant to corrosion and many chemical factors

  4. Have a high production cost


Correct Option: D
Explanation:
The properties and characteristics of most plastics (though not always fulfilled in certain special plastics) are these:
Easy to work and shape,
Have a low production cost,
Possess low density,
Tend to be waterproof,
Good electrical insulators,
Acceptable acoustic insulation,
Good thermal insulation, but most can not withstand very high temperatures,
Resistant to corrosion and many chemical factors;

The IUPAC name for Teflon is:

  1. polytrifluoroethane

  2. polytetrafluoroethane

  3. polytrifluoroethylene

  4. polytetrafluoroethylene


Correct Option: D
Explanation:
The IUPAC name of Teflon is Polytetrafluoroethylene (PTFE) which is a synthetic fluoropolymer of tetrafluoroethylene.  $ (C _2F _4) _n$. 

Teflon constitutes:

  1. carbon,flourine & hydrogen

  2. carbon,chlorine & hydrogen

  3. carbon & flourine

  4. carbon & chlorine


Correct Option: C
Explanation:
Teflon is the brand name of Polytetrafluoroethylene (PTFE) is a synthetic fluoropolymer of tetrafluoroethylene. The constituents of tetrafluoroethylene are carbon and fluorine formula is $ (C _2F _4) _n$. 

Which of the following is thermosetting polymer?

  1. Nylon

  2. Sealing wax

  3. Polysiloxanes

  4. Both B and C


Correct Option: C
Explanation:

Thermosetting polymers: These polymers are cross linked or heavily branched molecules, which on heating undergo extensive cross linking in moulds and again become infusible. These cannot be reused. Some common examples are polysiloxanes, bakelite, urea- formaldehyde resins, etc.

Three-dimensional molecules with cross-links are formed in the case of a:

  1. thermosetting plastic

  2. thermoplastic

  3. both (a) and (b)

  4. none of the above


Correct Option: A
Explanation:

Thermosetting plastic consists of chain of the  molecules which are cross-linked, with each other when heated. When thermosetting plastics cross-link, the molecules create a permanant, network  which is a $3-D$ structure and can be considered one giant molecule. Once cured, thermosetting plastic cn not be remelted, in the same way that cured concrete cannot be reset. 

Garden chairs made of plastic strips and plastic articles get faded, worn out and cracked in sunlight, mainly because of:

  1. Low melting point of plastic

  2. Ultraviolet rays

  3. Heat

  4. The red colour


Correct Option: B
Explanation:

Garden chairs made of plastic strips and plastic articles get faded, worn out and cracked in sunlight, mainly because of UV rays. All types of UV can cause a photochemical effect within the polymer which can lead to degradation of some sort to the materials. Absorbed UV energy can exits the photon in a plastic, exciting the photons can create free radicals. Those free radicals can cause breaks in the polymer bonds.

Which of the following are not thermosetting polymers ?

  1. Bakelite

  2. polystyrene

  3. PVC

  4. Melmac


Correct Option: B,C
Explanation:

Thermosetting polymers have different properties to thermosoftening polymers. Once moulded, they do not soften when heated and they cannot be reshaped. Vulcanised rubber is a thermoset used to make tyres. Its polymer chains are joined together by cross-links, so they cannot slide past each other easily.


Examples are given below:
  • Polyester fibreglass systems: sheet molding compounds and bulk molding compounds
  • Polyurithane insulating foams, mattresses, coatings, adhesives, car parts, print rollers, shoe soles, flooring, synthetic fibers, etc. Polyurethane polymers are formed by combining two bi- or higher functional monomers/oligomers.
  • Vulcanized rubber
  • Bakelite, a phenol formaldehyde resin used in electrical insulators and plasticware
  • Duroplast, light but strong material, similar to bakelite used for making car parts


Polyvinyl chloride(PVC) and polystyrene are thermoplastic polymer.
Hence, options B and C are correct.

State whether true or false :

Plastics are insoluble in water.

  1. True

  2. False


Correct Option: A
Explanation:

 Plastics are high molecular weight (macromolecular or polymeric) organic substances that are synthesized from low molecular weight compounds. 


The organic monomers are hydrophobic in nature due to the presence of hydrocarbons and thus makes plastics water insoluble.


Example: polyethene- a polymer of ethylene.

Therefore, option A is correct.

Statement: Teflon doesn't stick to the materials and can be easily used in non-sticky pans and other cookware.
  1. True

  2. False


Correct Option: A
Explanation:

Teflon is a synthetic polymer of polytetrafluoroethylene that can be used to cover the surface of a certain object and imparts nonstick properties to it.  


Teflon is used for non-stick material because :


1. It is highly inert, i.e. doesn’t react with other substances easily.

2. It has a high melting point and shows exceptional electrical properties, which makes it an excellent choice to be used for the wiring of computer and aerospace applications.

3. Non-stick quality, which is why it’s used in numerous frying pans, pots, and other culinary tools.

Hence, the given statement is $\text{true}$.

Statement: Plastics which get deformed easily on heating and can be bent easily are known as thermoplastics.


State whether the given statement is true or false.

  1. True

  2. False


Correct Option: A
Explanation:

Plastics are categorized into thermosoftening/thermoplastic and thermosetting/thermoset plastics.


In thermosoftening/thermoplastic, the forces between the polymer chains are weak, so they can easily be remoulded into new shapes. 

This makes it possible to recycle this type of plastic. whereas in thermosetting plastics there are strong covalent bonds forming cross-links between the polymer chains, making these plastics hard and rigid. Once set into its original shape, a thermosetting plastic can't be softened and remoulded. 

The strong bonds between polymers also mean that thermosetting plastics are much more heat resistant than thermosoftening ones.

Hence, the given statement is $\text{true}$

Plastics are capable of molding and casting into various shapes and size plastic.

  1. True

  2. False


Correct Option: A
Explanation:

Plastics are categorized into thermosoftening and thermosetting plastics.
In thermosoftening plastics, the forces between the polymer chains are weak, so they can easily be remoulded into new shapes. This makes it possible to recycle this type of plastic. whereas in thermosetting plastics there are strong covalent bonds forming cross-links between the polymer chains, making these plastics hard and rigid. Once set into its original shape, a thermosetting plastic can't be softened and remoulded. The strong bonds between polymers also mean that thermosetting plastics are much more heat resistant than thermosoftening ones.
Example: Melamine is an example of a thermosetting plastic and polythene is a thermosoftening plastic.
Option A is correct

State whether true or false :

Bakelite is the first synthetic thermosetting plastics.

  1. True

  2. False


Correct Option: A
Explanation:

Bakelite is prepared in laboratories by controlling the pressure and temperature applied to phenol and formaldehyde. 


Baekeland produced a hard moldable material which he named "Bakelite". 

It was the first synthetic thermosetting plastic ever produced.

Therefore, option A is correct

When plastics are burnt toxic substances are released into the air causing water pollution.

  1. True

  2. False


Correct Option: B
Explanation:

When plastics are burnt toxic substances are released into the air causing air pollution. Hence, the given statement is false.


Substances which cannot be decomposed by micro-organisms are called non-biodegradable substances.

  1. True

  2. False


Correct Option: A
Explanation:

Biodegradable substances are such materials which are and can be degraded by natural factors like microbes (e.g. bacteria, fungi and few more), abiotic elements like temperature, UV, oxygen, etc.
Unlike biodegradable, non-biodegradable substances like plastics, cannot be easily handled and cannot be decomposed or dissolved by natural agents.
Option A is correct

Plastics are eco-friendly.

  1. True

  2. False


Correct Option: B
Explanation:

Plastics are human-made polymers and are non-biodegradable which means they cannot be easily handled and cannot be decomposed or dissolved by natural agents like microbes (e.g. bacteria, fungi), abiotic elements like temperature, UV, oxygen, etc. Thus are not eco-friendly.
Option B is correct

Which of the following is non-biodegradable?

  1. Plastic

  2. Cotton

  3. Paper

  4. Left-over food


Correct Option: A
Explanation:

The plastics are the non-biodegradable wastes because they are synthetic polymers which cannot be acted upon by the microbes. They cannot be degraded by the decomposition activity of the bacteria and fungi. The cotton, paper and leftover food are degradable. 

Thus, the correct answer is option A. 

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