Polymers - Class 12 Engineering Chemistry - Extra Questions

Write any two differences between step growth polymerisation and chain growth polymerisation.

 Step Growth  Chain Growth
 All molecules present (monomer, oligomer, polymer) can react with any other molecule. During propagation, only monomers react to the “active site” at the end of the growing chain
 There is no termination step and the end groups of the oligomers and polymers are reactive throughout the polymerization process. There are two distinctive mechanisms during polymerization; these are initiation and propagation. In most cases there is also a termination step.


What is the code number on plastic bottle HDPE?

HDPE stands for High-density polyethylene and it's recycling no. (code no.) is 2.


What is the utility of vulcanisation of rubber? How is vulcanisation carried out?

Natural rubber has the following drawbacks:
$$1)$$ It is soft and sticky at room temperature. At high temperatures, $$(>\ 335\ K)$$, softness increases. 
At low temperatures, $$( <\ 283\ K)$$, it is brittle. 
Hence, to maintain elasticity, natural rubber can be used in the temperature range of $$283\ K\ - \ 335\ K$$.
$$2)$$ It can absorb large amounts of water.
$$3)$$ It's tensile strength is low and it has low resistance to abrasion.
$$4)$$ It is soluble in non-polar solvents.
$$5)$$ It is easily attacked by oxidizing agents.
Vulcanization is carried out to improve this property. This process involves heating a mixture of raw rubber with sulphur and other additives at a temperature range between $$100^{\circ}C$$ to $$145^{\circ}C$$.
After vulcanization sulphur forms cross-links at the reactive sites of double bonds and thus the rubber gets stiffened.

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Which catalyst is used in the preparation of dacron?

Dacron is manufactured by heating a mixture of ethylene glycol and terephthalic acid at $$420 - 460 \; K$$ in the presence of zinc acetate- antimony trioxide catalyst.


Match the following:


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explane this reaction
$$H_{2}+I_{2}$$ = 2HI


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Match the List I with the List II.

Some of the polymers have been given abbreviations such as:
PET $$\longrightarrow$$ Polyethylene terephthalate.
PVC $$\longrightarrow$$ Polyvinyl chloride.
LDPE $$\longrightarrow$$ Low Density Polyethene.
PP $$\longrightarrow$$ Polypropylene.
PS $$\longrightarrow$$ Polystyrene.


Illustrate the following terms :

(a) Copolymerization (b) Vulcanization

(a) Copolymerization: When two different kinds of monomers are polymerized together to give a product containing both the monomers. Such a process is known as copolymerization.

 (b) Vulcanization: Vulcanization is a chemical process in which the rubber is heated with sulphur, accelerator and activator at 140–160°C. The process involves the formation of cross-links between long rubber molecules so as to achieve improved elasticity, resilience, tensile strength, viscosity, hardness and weather resistance.


Statement: The monomer used for the preparation of polythene is ethylene.

 If true enter 1 else 0.


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Why is teflon used as a tape for sealing purpose?

Teflon is used as a tape for sealing purpose because of its toughness. It is used to make leak free tapes.


Write two names of polymer which are biodegradable.

The examples of biodegradable polymers are as follows:

(i) PLA - polylactic acid 

(ii) PHBV - poly(3-hydroxybutyrate) or poly(4-hydroxybutyrate)


Why teflon is used to make nonstick cooking pans and other cookwares ?

Teflon is polytetrafluoroethylene which is a fluorocarbon solid. It is non reactive because of strength of C-F bonds.


What do you know about Bakelite?


Bakelite: It is a thermosetting polymer formed from phenol and formaldehyde by condensation polymerization.
Uses of Bakelite:
(i) Due to its high resistance to electricity it is used in automotive components and industrial applications.
(ii) Due to excellent insulating properties, it is used in switches and electrical appliances.
(iii) It is also used in making toys and other kitchenware products such as the handle of the frying pans, cookers, etc.

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How do you explain the functionality of a monomer?

Functionality of a monomer is the number of bonding sites present in the monomer.

For example, the monomers ethene and propene have the functionality of $$1$$ each.

The monomers $$1,3$$-butadiene and adipic acid have the functionality of $$2$$ each.


Define the term polymerisation.

Polymerisation is a process of formation of polymers of a high molecular mass from one or more monomers by linking together repeating structural units with covalent bonds. In these polymers, the molar mass is about $$\displaystyle 10^3 - 10^7 $$ u. Thus, ethylene polymerizes to form polythene and tetra fluoro ethylene polymerizes to form teflon.

As shown in the figure adipic acid and hexamethylene diamine polymerizes to form nylon 6,6.

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What are natural and synthetic polymers? Give two examples of each type.

$$\text {Natural polymers}$$
Natural polymers are high molecular mass macromolecules and are found in nature (plants and animals). They are formed by plants and animals.
The examples are proteins, nucleic acids, cellulose, starch etc.

$$\text {Synthetic polymers}$$
Synthetic polymers are man-made high molecular mass macromolecules. These include synthetic plastics, fibres and rubbers. The two specific examples are polythene and dacron.


Write the name and structure of one of the common initiators used in free radical addition polymerisation.

Benzoyl peroxide is the initiator used in free radical addition polymerization.
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Discuss the main purpose of vulcanisation of rubber.

Natural rubber has the following drawbacks:
$$1)$$ It is soft and sticky at room temperature. At high temperatures, $$(>\ 335\ K)$$, softness increases.
At low temperatures, $$( <\ 283\ K)$$, it is brittle.
Hence, to maintain elasticity, natural rubber can be used in the temperature range of $$283\ K\ - \ 335\ K$$.
$$2)$$ It can absorb large amounts of water.
$$3)$$ It's tensile strength is low and it has low resistance to abrasion.
$$4)$$ It is soluble in non-polar solvents.
$$5)$$ It is easily attacked by oxidizing agents.
To improve upon these drawbacks, natural rubber is vulcanized. It (along-with sulphur and appropriate additive) is heated at a temperature range between $$373\ K$$ and $$415\ K$$.


Explain the terms polymer and monomer.

$$\text {Polymer}$$ 
Polymer is a high molecular mass macro-molecule consisting of repeating structural units derived from monomers. The molar mass of polymer is around $$\displaystyle 10^3 - 10^7 \: u$$.
There are strong covalent bonds which joints various monomer units in a polymer.
Examples of polymers include Rubber, polythene, Teflon and nylon $$6,6$$.

$$\text {Monomer}$$
Monomer is a simple molecule capable of undergoing polymerization and leading to the formation of the corresponding polymer. Monomers are reactive molecules that combine with each other in large numbers through covalent bonds to form polymers. 
Examples of monomers include ethene, propene, styrene and vinyl chloride.

In the given reaction Adipic acid and hexamethylenediamine are monomers and nylon 6,6 is a polymer.

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Distinguish between the terms homopolymer and copolymer and give an example of each.

$$\text {Homopolymers}$$ are formed by the polymerisation of a single monomer. The repeating units of homopolymers are derived only from one monomer. Examples includes polythene which is a homopolymer of ethene.

In $$\text {copolymers}$$, the repeating units are derived from two types of monomers. Example includes $$Buna-S$$, which is a copolymer of $$1,3-butadiene$$ and $$styrene$$.


Define the term polymerisation

$$ \displaystyle  (NH−CHR−CO)_n$$ is a homopolymer as it is obtained from a single monomer unit, $$ \displaystyle  NH_2−CHR−COOH$$. 

Note: Homopolymers are formed by the polymerisation of a single monomer. 

The repeating units of homopolymers are derived only from one monomer.

In copolymers, the repeating units are derived from two types of monomers.


Write the free radical mechanism for the polymerisation of ethene.

In the chain initiation step, the decomposition of benzoyl peroxide gives benzoyl free radical which further gives phenyl free radical.

Phenyl free radical adds to C=C double bond of ethene and generates a new free radical.

In chain propagating step, the newly generated free radical adds to another ethene molecule to form larger free radical. This process repeats several times.

In the chain termination step, two free radicals combine to form polyethene.

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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.

                                    Can be recycled              Cannot be recycled
Plastic toys, carry bags, ball point pens, plastic bowls, plastic covering on electrical wires, plastic chairsCooker handles, electrical switches and Telephone instruments


Write the names and structures of the monomers of the following polymers: 

(i) Buna-S    (ii) Buna-N   (iii) Dacron    (iv) Neoprene

The names and structures of monomers are given below:

Polymers     Monomer Names      Monomer Structures
(i)Buna-S  1,3-Butadiene
$$CH_2=CHCH=CH_2$$


Styrene$$C_6H_5CH=CH_2$$

(ii)Buna-N1,3- Butadiene$$CH_2=CHCH=CH_2$$


Acrylonitrile$$CH_2=CH CN$$

(iii)Neoprene   Chloroprene  $$\begin{matrix} &Cl  &  \\  &|  &  \\CH_2= &C&-CH=CH_2\end{matrix}$$
(iv)DacronEthylene glycol  $$OHCH_2CH_2OH$$


Terephthalic acid   $$p-HOOC-C_6H_4-COOH$$


What is a biodegradable polymer ? Give an example of a biodegradable aliphatic polyester.


A biodegradable polymer can be decomposed by bacteria. Non-biodegradable polymer cannot be decomposed by bacteria.
PHBV (Poly- $$\beta$$-hydroxybutyrate-CO-$$\beta$$-hydroxyvalerate) is an example of a biodegradable aliphatic polyester.
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Which of the following is a fibre?
Nylon, Neoprene, PVC

Nylon is a fiber. Another example of fiber includes terylene. Neoprene and PVC don't form fibre.
Due to presence of strong hydrogen bonds, the polymer chains form fibers. Such polymers possess high tensile strength.


Write the name of monomers used for getting the following polymers:
(i) Bakelite            (ii) Neoprene

(i) Bakelite is a phenol-formaldehyde polymer. The monomers used are phenol and formaldehyde.       

(ii) Neoprene is obtained by polymerisation of chloroprene (2-chlorobuta-1,3-diene).

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Write the names and structures of the monomers of the following polymers.

(i) Bakelite (ii) Nylon-$$6,6$$ (iii) Polythene

$${i) Bakelite}$$

Bakelite is a condensation polymer of phenol and formaldehyde.

Thus its monomers are as follow:
$$\underset{phenol}{C_6H_5OH}$$ and $$\underset{formaldehyde}{HCHO}$$

$${ii) Nylon-6,6}$$ 

It is the condensation polymer of adipic acid and hexamethylene diamine.
Here 6 represents the number of carbon atoms in each monomer.

The two monomers of Nylon-6,6 can be given as follow:
$$\underset{adipic\ acid}{HOOC-(CH_2)_4-COOH}$$ and $$\underset{hexamethylene\ diamine}{H_2N-(CH_2)_6-NH_2}$$

$${iii) Polyethene}$$

Polyethene is an addition polymer of ethene.

$$\underset{ethene}{nCH_2=CH_2}\xrightarrow{Polymerization} (-CH_2-CH_2-)_n$$


Write the name and structures of the monomers of the following polymers.
(i) Terylene
(ii) Buna-S
(iii) Neoprene 



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As plastics and synthetic fibres consist of repeating monomer units, they are known as __________.

The answer is $$Polymers$$

Polymers: They are large molecules made of small repeating units. Due to their broad range of properties, synthetic polymers and plastics are used.


Write the name of monomers used for getting the following polymers:
(i) Teflon  (ii) Buna-N

(i) Teflon is obtained from tetrafluoroethylene, $$\displaystyle CF_2 = CF_2 $$.
Teflon is an addition polymer.
(ii) Buna-N is a copolymer of acrylonitrile, $$\displaystyle CH_2=CH-CN $$ and 1,3-butadiene, $$\displaystyle CH_2 = CH- CH =CH_2 $$ .
Buna-N is a synthetic rubber.


Write the names and structures of the monomers of the following polymers.

(i) Polystyrene
(ii) Dacron
(iii) Teflon

1. Polystyrene is a synthetic aromatic polymer made from the monomer styrene.

2. Dacron consists of polymerized units of the monomer ethylene terephthalate, with repeating ($$C_{10}H_8O_4$$) units.


3. Teflon:
Polytetrafluoroethylene (PTFE) is a synthetic fluoropolymer of tetrafluoroethylene. 




Give one example of a condensation polymer.


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State True or False.
 
Nylon has high elasticity and tensile strength.

Fibers have very high tensile strength and good flexural strength as well, but they usually have terrible compressional strength. They also only have good tensile strength in the direction of the fibers. 

Nylon has the highest elastic limit of the polymers and although it does not meet our min. elastic limit requirement, it has a high coefficient of restitution. Polymers with a comparable elastic limit probably behave similarly.

Hence, the given statement is true.


 We use PET bottles. PET jars for storing sugar, dal, salt etc., what is this PET exactly?

PET i.e. Polyethylene terepthalate is very famous term for polyester. Water bottles and many containers used in kitchen, films, wires, and many other useful products are made using PET polyester.



What are broad-spectrum antibiotics ?
How are polythene and neoprene prepared ?

Those antibiotics which are effective against a wide range of gram positive and gram negative bacteria are known as broad-spectrum antibiotics.
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Write names and chemical formulae of monomers used in preparing Buna-S.

The material Buna $$S$$ derives $$Bu$$ for butadiene, $$Na$$ for sodium and $$S$$ for styrene. The monomers used in preparing Buna $$S$$ are (i) Butadiene, $$CH_{2} = CH - CH = CH_{2}$$ and (ii) Styrene,

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Write the names of monomers of the following polymers :
(a) Bakelite
(b) Terylene

The names of monomers of the polymers are given below:
(a) Bakelite: Phenol and formaldehyde
(b) Terylene: Ethylene glycol and dimethylterephthalate


What is vulcanization of rubber?

Vulcanization of rubber is the process of converting natural rubber to more strong and elastic form. Natural rubber is mixed with 3 to 5% sulphur and heated at $$100$$ to $$150^o C$$ to form cross linking of $$cis-1,4-polyisopropene$$ chains through disulphide bonds.


Write the names of the monomers of PHBV polymer.

PHBV polymer is obtained from monomers $$\displaystyle \beta $$- hydroxy butrate $$\displaystyle (CH_3CHOH CH_2COOH)$$ and $$\displaystyle \beta $$ - hydroxy valarate $$\displaystyle CH_3CHOH(CH_2)COOH$$


Give the complete name for $$PHBV$$. How it is useful?

PHBV is a copolymer. It is polyhydroxy butyrate -CO- $$\beta$$-hydroxy valerate. The monomers used are 3-hydroxy butanoic acid and 3- hydroxy pentanoic acid. It has an ester linkage. It is useful to mankind because it is biodegradable polymer and thus, prevents environmental pollution.


Write the chemical reaction to prepare novolac polymer.

The monomers used in the preparation of novolac polymer are phenol and formaldehyde. They undergo polymerisation in presence of alkali or acid as catalyst. Phenol reacts with formaldehyde to form ortho or p-hydroxy methyl phenols, which on further reaction with phenol form a linear polymer called Novolac.
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What is PHBV? How is it useful to man?

PHBV is a copolymer. It is polyhydroxy butyrate -CO- $$\beta$$-hydroxy valerate. The monomers used are 3-hydroxy butanoic acid and 3- hydroxy pentanoic acid. It has an ester linkage. It is useful to mankind because it is biodegradable polymer and thus prevents environmental pollution.


.(a) Explain the addition polymer by an example.
(b) Write the equation of preparation of synthetic rubber.
(c) Give the names of monomers used for obtaining dacron.

(a) The addition polymer is formed by chain growth polymerisation. The monomer is alkene (such as ethylene). The addition polymer contains all the atoms of monomers. For example polythene is an addition polymer.
$$\displaystyle n CH_2=CH_2 \xrightarrow {\text {polymerisation}} [-CF_2-CF_2-]_n$$

(b) Write the equation of preparation of synthetic rubber.
(i) Buna-S or styrene butadiene rubber:
$$\displaystyle nC_6H_5-CH=CH_2 + nCH_2=CH-CH=CH_2 \xrightarrow {K_2S_2O_8} [-C(C_6H_5)-CH_2-CH_2-CH=CH-CH_2-]_n$$
(ii) Buna-N:
$$\displaystyle n CH_2=CH-CN + nCH_2=CH-CH=CH_2 \xrightarrow { \text {polymerisation}} [-CH_2-CH=CH-CH_2-CH_2-CH(C)-]_n$$
(iii) Neoprene rubber:
$$\displaystyle n CH_2=C-Cl-CH=CH_2  \xrightarrow [\text { or benzoyl peroxide }]{O_2  } [-CH_2-C(Cl)=CH-CH_2-]_n$$

(c) Monomers used for obtaining dacron are ethylene glycol and dimethylterephthalate.


(a) What is addition polymer? Give example.
(b) What is PHBV? How is it useful to man?

(a) An addition polymer is formed by chain growth polymerization. The addition polymer contains all atoms of monomers. The monomers are alkenes. Examples of addition polymers include Orlon, Teflon, PVC, Polythene etc. .
Thus, polymerisation of vinyl cyanide gives Orlon
$$ \displaystyle n CH_2=C(CN)H \xrightarrow {polymerization} -[-CH_2-C(CN)H-]-_n$$
Similarly, polymerization of tetrafluoroethylene gives teflon.
$$ \displaystyle n CF_2=CF_2 \xrightarrow {polymerisation} -[-CF_2-CF_2-]-_n$$

(b) PHBV is a copolymer. It is polyhydroxy butyrate -CO- $$\beta$$-hydroxy valerate. The monomers used are 3-hydroxy butanoic acid and 3- hydroxy pentanoic acid. It has an ester linkage. It is useful to mankind because it is biodegradable polymer and thus prevents environmental pollution.


What is PHBV ? How is it useful to man ?

Explanation:

Part 1:

The product formed by the copolymerization of $$3-hydroxybutyric-acid$$ and $$3-hydroxypentanoic-acid$$ is known as PHBV.

PHBV stands for poly $$\beta$$ -hydroxybutyrate-co-$$\beta$$ -hydroxy valerate.

Part 2:

The chemical reaction involved in production of PHBV is

$$CH_3-CH\left ( OH \right )-CH_2-COOH+CH_3-CH_2-CH\left ( OH \right )CH_2COOH\rightarrow $$

$$\left ( -O-CH\left ( CH_3 \right )CH_2-C\left ( O \right )-O-CH\left ( C_2H_5 \right )-CH_2-C\left ( O \right )- \right )_n$$

Part 3:

It is used in specialty packaging, orthopedic devices, and in controlling the release of drugs.

PHBV undergoes bacterial degradation in the environment.



Explain that vulcanised rubber is an elastomer.

On stressing elastomer, the polymer chain stretches, but due to cross linking tearing is prevented. On relieving the strain, the chain returns to its original position. Thus elastomers shows elasticity. Such polymers are stretchy. 
During vulcanisation, natural rubber undergoes cross linking of cis-1,4 polyisoprene chains through disulphide bonds. This makes vulcanised rubber tough, elastic and stretchy. Hence, vulcanised rubber is an elastomer.


Write the names and structures of monomers used for getting the following polymers.
(i) Teflon
(ii) Bakelite

The names and structures of monomers used for getting the polymers are as given below.
(i) Teflon : Tetrafluoroethylene $$\displaystyle CF_2=CF_2$$
(ii) Bakelite : Phenol $$\displaystyle C_6H_5-OH$$ and formaldehdye $$\displaystyle H-\underset {\displaystyle \underset {\displaystyle O }{ || } }{C} -H$$
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a) i) Explain the preparation of Buna-N.
ii) Give an example for thermosetting polymer.
b) Name the monomers used in the preparation of polythene and natural rubber.

a) i) Buna-N is co polymer of 1,3 butadiene and acrylonitrile.

ii) Thermosetting polymers are Melamine formaldehyde, polyster resin.
b) Polyethene is made up of ethelene monomer units and natural rubber is 2-methyl 1,3 butadiene(isoprene) monomer units.

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What is Polymerisation?  Write the names of any three polymers and their one main use.

The process of formation of molecules of polymers bye the combination of small unit molecules, is called polymerisation
Polymers are large molecules, consisting of a large number of small units called monomers e.g. when Ethylene is heated at high temperature and high pressure, its molecules unite together to form a high molecular weight compound called Polythene. This process is called Polymerisation.

 $$ n(CH_2 = CH_2) \xrightarrow [High \quad temperature \quad and \quad high \quad pressure] {Polymerisation} \underset {Polythene}{(-CH_2 - CH_2 -)_n} $$   where n is the number of molecules.

In the same way, Polyvinyl Chloride (P.V.C.), Teflon, Neoprin etc. are also polymers.

Some important polymers, their method of preparation, properties and uses -
1. Polythese (Poly + Ethene = Polythene) It is a synthetic polymer of the additional series. 
It's monomer unit is ethylene.
$$ n(CH_2 = CH_2) \xrightarrow [1000-200 A.P.] {Polymerisation} \underset {Polythene}{(-CH_2 - CH_2 -)_n} $$
Property - It is transparent, elastic, strong, and solid plastic.
use - It is used in making raincoats, toys, pipes, bags etc.
 
2.Polyvinyl Chloride (P.V.C.) - It is also synthetic polymer of additional series. It's monomer unit is Vinyl chloride.

$$ \underset {(Vinyl Chloride)}{CH_2 = CH.Cl} \longrightarrow \underset {Poly Vinyl Chloride} { -CH_2 \overset { CH }{ \underset { cl }{ | }  } } $$
Properties - It is a hard polymer.
Uses - It is used in making floor tiles, pipes, toys etc.\

$$ \underset{Tetra** \quad Fluro \quad Ethnene} {n(CF_2 = CF_2)} \longrightarrow \underset {Teflon}{(-CF_2 - CF_2 -)_n} $$
 Properties - It is a hard and heat resistant substance.
Uses - It is used in making non stick utensils.


What are the monomers of the following?
(i) Neoprene
(ii) Nylon-$$6$$

  • Monomer of Neoprene is chloroprene.

  • Nylon - 6 is only made from one kind of monomer, a monomer called caprolactam.



(a) Complete the reaction?
(b) Name the product formed if a large number of $$CH_2 = CH_2$$ molecules are added instead of $$H - H$$?
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(a) $$CH_2 = CH_2 + H - H \rightarrow CH_3 - CH_3$$
(b) Polythene will be formed; $$n[CH_2 = CH_2] \rightarrow [-CH_2 - CH_2]_n$$


What are Polymers? Give the name of two polymers and their uses.

Polymers are macromolecules having high molecular weights and composed of smaller repeating units called monomers. The term polymer is derived from Greek roots 'poly' means 'many' and 'meros' means 'part'.

(1) Acrylonitrile (A), butadiene (B) and styrene (S) combine together to form ABS plastic (a polymer) which is tough, strong and used to prepare articles which withstand heavy impacts.

(2) Vinylidene chloride and vinylchloride form a polymer used as a film for wrapping food (polymer is called saran).


What is the common name of the polymer obtained by the polymerization of caprolactum? Is it addition polymer or condensation polymer?

The common name of the polymer obtained by the polymerization of caprolactum is nylon-6. It is condensation polymer.
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Give two examples of bio-degradable polymers?

Bio degradable polymers degrade on their own. Some bio degradable polymers include Dextron, nylon-2-nylon-6 and PHBV polymer (Poly(3-hydroxybutyrate-co-3-hydroxyvalerate)).


Why sulphur is added to the natural rubber?

Natural rubber is soft, sticky and has less tensile strength. It is vulcanized to make it more strong, tough and elastic.
For vulcanization, $$3$$ to $$5$$ % sulfur is added to natural rubber and is heated at $$100$$ to $$150^oC$$.


Write the values(at least two) shown by Shyam.

Following values were shown by Shyam.
(1) Compliance with government regulations.
(2) Care and concern for the environment.


Write the difference between terylene fibers and Buna-s rubber (clastomers).

TERYLENE

BUNA-S

1. Monomers: Terephthalic acid and ethylene glycol.

2. Fibre.

3. Strong binding force.

 

1. 1,3-butadiene and styrene.

 

2. Elastomer.

3. Weak binding force.

 


Write one structural difference between low-density polythene and high-density polythene.

Low-density polythene is branched polymer. High-density polythene is linear polymer.


Write the names of the monomers for each of the following polymers:
(a) Bakelite
(b) Nylon-2-nylon-6

(a) Bakelite is a polymer of Phenol and formaldehyde (methanal)
(b)Nylon-2-nylon-6- is a glycine and amino caproic acid (6-amino hexanoic acid)


Consider the following reaction involved in the preparation of teflon polymer $$(-CF_{2} - CF_{2}-)_{n}$$
$$XeF_{2} + (-CH_{2}-CH_{2}-)_{n} \rightarrow (-CF_{2}-CF_{2}-)_{n} + HF + XeF_{a^{-}}$$.
Determine the moles of $$XeF_{5}$$ required for preparation of $$100\ g$$ Teflon.

$$XeF_2+(CH_2-CH_2)_n\rightarrow (CF_2-CF_2)_n+XeF_a$$
for one $$(CF_2-CF_2)$$ the mass$$=100$$gm
formation one teflon, for which $$n=1$$
$$2XeF_2+(CH_2-CH_2)(CF_2-C_2)_1+2Xe$$
$$2$$ moles of $$XeF_2$$ produce $$1$$ mole of $$(CF_2-CF_2)_1$$
whcih is $$100$$gm teflon so, $$2$$ moles of $$XeF_2$$ is requried to produce $$100$$gm of Teflon.

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What are the differences between Buna-N and Buna-S ?

                BUNA-N                     BUNA-S
(1) Monomers 1,3-butadiene and acrylonitrile.

(2) Also called as Nitrile-Butadiene-Rubber (NRB).

(3) It is formed by polymerization of 1,3-butadiene and acrylonitrile in the presence of sodium.

(4) Used in making oil seals, manufacturing of tanks,etc.
 (1) Monomers:1,3-butadiene and styrene. 

(2) Also called as Styrene-Butadiene-Rubber (SBR).

(3) It is formed by the polymerization of 1,3-butadiene and styrene in the ratio 3:1 in the presence of sodium.

(4) Used for making automobile tyres , etc.


Very short answer type.
Name the monomer(s) of the following dimers/polymers starch 

Starch is a carbohydrate polymer made up of monomers of glucose. Each monomer is joined to each other by glycosidic bonds.


Name the monomer present in the following polymer
i) Polyvinyl chloride.
ii) Natural rubber.

i) The monomer present in Poly vinyl chloride is Vinyl chloride.
ii) The monomer present in Natural rubber is Isoprene (2-methyl-1,3-butadiene).
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Give an example of bio-degradable polymer.

Poly $$\beta$$-hydroxybutyrate- Co- $$\beta$$-hydroxyvalerate(PHBV), Dextron and nylon-2-nylon6 are examples of bio-degradable polymers.


Explain the preparation of Buna-N with equation.

Buna-N is obtained by co-polymerisation of $$1,3$$-butadiene and acrylonitrile in the presence of a peroxide catalyst.
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Given the chemical reaction for the preparation of Nitrile rubber. Also mention its two properties and two uses.

Nitrile rubber, also known as NBR, Buna-N, is a synthetic rubber copolymer of acrylonitrile (ACN) and 1,4-butadiene. 
Properties:
1. Possesses a high tensile strength ( $$≥ 10 N/mm^2$$).
2.Good resistance to mineral oils, vegetable oils, benzene/petrol, ordinary diluted acids and alkalines.
Uses:
1. In the manufacturing of disposable non-latex gloves, automotive transmission belts, gaskets, synthetic leather etc.
2.It can also be used in the preparation of adhesives and as a pigment binder.

887700_961263_ans_0674111259b0485586fd51e62256653b.png


Name the polymer which is obtained from acrylonitrile.

Polymer obtained from acrylonitrile is poly(acrylonitrile).
1158080_1119388_ans_08d429228cd94d30a47ed508f93dfc7e.PNG


What does term $$SBR$$ stand for ? write its application.

$$SBR$$ stands for Styrene-butadiene Rubber which is formed from $$1,3-$$ butadiene and styrene.
1174438_1119393_ans_c640f7d184d8432bb2d426b5f5cc90eb.PNG


Answer the following in brief:
Name of the process of formation of polymer form its monomer.

Formation of polymer from its monomer is called Polymerization.
There are $$2$$ type of Polymerization:
(i) Addition Polymerization:
Small monomers are added on resulting in chain growth or branching but no byproduct is formed. Examples- Polyethylene, polystyrene, etc.
(ii) Condensation Polymerization:
Small monomers are added to form large macromolecules and also a by-product is formed. Examples- Nylon $$6$$, Bakelite, etc.


Write uses of Bakelite.

Uses of Bakelite: Due to its high tensile strength it is used for making many products such as telephone, electrical gadgets, jewellery, saucepan handle, etc.
Bakelite is a thermosetting polymer. It is formed from formaldehyde and phenol.

1030473_1119382_ans_d8f0e2893786404d820244ed3109ccb7.PNG


(1)Name the material prepared by using wood pulp.
(2)Name the natural polymer.

Rayon is prepared by using wood pulp.
Examples of natural polymers are silk, wool, DNA, cellulose and proteins.


Explain the difference between Buna-$$N$$ and Buna$$-S$$.

Buna -N
(1) It is copolymer of 1,3-butadiene and acrylonitrile
(2) It is also called as Nitrile Rubber(NBR)
(3)It is used in making oil seels ,used in manufacturing of tank linings, and protective gloves
(4)It is obtained by polymerisation of 1,3-butadiene and acrylonitrile in the presence of sodium

Buna -S
(1) It is a copolymer of 1,3 -butadiene and styrene.
(2) It is also called as styrene butadiene rubber(SBR)
(3) It is used for making automobile tyres, rubber soles,belts,hoses etc
(4)It has slightly less tensile strength than natural rubber
(5) It is obtained by polymerisation of 1,3-Butadiene and styrene in the ratio 3:1 in the presence of sodium.


Write differences between low and high density polymers.

Low Density Polyethylene:
It is a thermoplastic polymer made from monomer of ethene, manufactured under high pressure and temperature.
LDP has more branching thereby having weak intermolecular forces and hence have low tensile strength.
High Density Polyethylene:
It is a thermoplastic polymer made of monomer ethylene. It is having high-strength to density ratio. It has strong intermolecular force than LDP and hence have high tensile strength.


Explain why free radical polymerisation of styrene gives a product in which phenyl groups are on alternate carbon atoms rather than on adjacent carbon atoms.


1343106_1134539_ans_fc8762b3592a456db5afaac51f4f215f.jpg


Name the phenol-formaldehyde polymers.

Bakellite is the phenol formaldehyde polymer.
It is obtained by the condensation reaction of phenol with formaldehyde in the presence of either an acid or a base catalyst.


What is the commercial name of PMMA? What is its use?

Poly(methyl methacrylate) (PMMA), also known as acrylic or acrylic glass as well as by the trade names Crylux, Plexiglas, Acrylite, Lucite, and Perspex among several others, is a transparent thermoplastic.
$$Use$$- Often used in sheet form as a lightweight or shatter-resistant alternative to glass.


Explain the term with example:Monomer

Monomer$$:-$$ 

                Basic structural unit which repeat again and again to form polymer is called monomer$$.$$
M$$ \to $$ $$C{F_2}:C{F_2} \to {\left( { - C{F_2} - C{F_2} - } \right)_n}$$
       Monomer                     


classify the following as addition and condensation polymers:
Terylene, Bakelite, Polyvinyl chloride,Polythene

Addition polymers: Polyvinyl chloride, Polythene

Condensation polymers: Terylene, Bakelite

'


Which polymer is obtained from $$2-$$chlorobuta$$-1, 3-$$diene?

2-chlorobuta -1,3-diene (IUPAC name) for 
chloropronce chloroprene is a colorless volatile  
liquid, exclusively used as a monomer for the 
production of the polymer polychorprence, a type 
of synthetic robber. Polychloroprene is batter  
know as Neoprene 
$$ CH_{2} = CCl - CH = CH_{2}\Rightarrow 2$$ - chlorobuta - 1,3-diene 
Neoprene is sold either as solid rubber or in 
later form & is used in a wide variety & 
applications such as laptop sleeves, orthopaedic  
braces (wrist, knee etc), electrical insulation etc.


1131634_1143403_ans_45fe98c388c94f1ab935a1926c25f6a7.jpg



Write the structure of monomer and name the given polymer.
1250355_fbec0558bec14b4296adeeda0ababdb3.png

Nylon 6 is made from one kind of monomer, a monomer called caprolactam.

This structure is Nylon 6.

1312951_1250355_ans_bd4310ce1cff4d8694be8c35ae4ca2d5.png


Predict missing product 
1360144_99637d9359c04ed5919b65d9fe4d9cb4.PNG


1312963_1360144_ans_715496859de04ab8814f85e7e4790e1f.PNG


Difference between homopolymer and co-polymer.

The main difference between homopolymer and copolymer is that homopolymers are produced by using a single type of monomer, whereas copolymers are formed by using two different types of monomers. Because of this difference, both homopolymers and copolymers gain their unique set of properties.


Name the monomers present in the following polymers:
(a) Bakelite
(b) Buna- N

  • (a) Phenol and formaldehyde are the monomer units of bakelite.
Phenol: $${C}_{6}{H}_{5}-OH$$
Formaldehyde: $$HCHO$$
  • (b) $$1,3$$-butadiene and acrylonitrile are the monomer unit of Buna-N.
$$1,3$$-butadiene: $$C{H}_{2}=CH-CH=C{H}_{2}$$
Acrylonitrile: $$C{H}_{2}=CH-CN$$


What is biodegradable polymer ? Give one example.

Biodegradable polymer $$\rightarrow$$ A polymer that can be decomposed by bacteria is called a biodegradable polymer.
These polymers contain functional groups similar to groups present in biopolymers
PHBV, Nylon-2-Nylon-6 are some examples of biodegradable polymers.


Write the names of the monomers of the following polymers:
(a) Bakelite
(b) Nylon - 6,6

  • (a) Phenol and formaldehyde are the monomer units of bakelite.
Phenol: $${C}_{6}{H}_{5}-OH$$
Formaldehyde: $$HCHO$$
  • (b) Hexamethylendiamine and adipic acid are the monomer unit of Nylon-$$6, 6$$.
Hexametylenediamine: $${H}_{2}N-C{H}_{2}-C{H}_{2}-C{H}_{2}-C{H}_{2}-C{H}_{2}-C{H}_{2}-N{H}_{2}$$
Adipic acid: $$COOH-C{H}_{2}-C{H}_{2}-C{H}_{2}-C{H}_{2}-COOH$$


Thermocol is produced from which material?

Thermocol is produced from complex material called polystyrene. It transforms into liquid state on heating at more than $$100^{o}C$$ and returns to solid state on cooling.


Is $$[ \mathrm { CH } _ { 2 } - \mathrm { CH } \left( \mathrm { C } _ { 6 } \mathrm { H } _ { 5 } \right) ]_{ \mathrm { n } }$$ to a homopolymer or a copolymer? 


1657271_1470813_ans_7519434d3b1e4bcaa5ba525c0bbf75c6.jpg


Explain the purpose of vulcanization of rubber.

Natural rubber becomes soft at high temperature and brittle at low temperatures. To improve physical properties of rubber, vulcanization is carried out. This process consists of heating a mixture of raw rubber with sulphur and an appropriate additive at a temperature range between $$373 \; K$$ and $$415 \; K$$. On vulcanization, sulphur forms cross-links at the reactive sites of double bonds and thus the rubber gets stiffened.
1181743_1435480_ans_e7c6e5ed93d5484cb71a4fcab38571b6.png


What is the structural difference between high density polythene (HDP) and low density polythene (LDP)?

High density polythene is a linear polymer, i.e., consist of long and straight chains while low density polythene is branched chain polymer, i.e., contains linear chains having some branches.


What are biodegradable polymers ? Give chemical equation for the preparation of any one biodegradable polymer.

Biodegradable polymer $$\rightarrow$$
A polymer that can be decomposed by bacteria is called a biodegradable polymer.
Poly $$\beta$$-hydroxybutyrate - co-$$\beta$$-hydroxy valerate (PHBV) is an example of biodegradable polymer.
Preparation of PHBV:-
$$\underset{3-\text{Hydroxybutanoic acid}}{C{H}_{3}-\overset{\underset{|}{OH}}{CH}-C{H}_{2}-COOH} + \underset{3-\text{Hydroxypentanoic acid}}{{C}_{2}{H}_{5}-\overset{\underset{|}{OH}}{CH}-C{H}_{2}-COOH} \longrightarrow \underset{\text{PHBV}}{{\left( -O-\overset{\underset{|}{C{H}_{3}}}{CH}-C{H}_{2}-\overset{\underset{||}{O}}{C}-O-\overset{\underset{|}{{C}_{2}{H}_{5}}}{CH}-C{H}_{2}-\overset{\underset{||}{O}}{C}- \right)}_{n}}$$



Write the structures of monomers used to obtain the following polymers:
(a) Neoprene
(b) PHBV
(c) Bakelite

(a) Neoprene $$\rightarrow$$ Neoprene is formed by the free radical polymerisation of chloroprene.

$$\underset{\left( \text{Chloroprene} \right)}{C{H}_{2}-\overset{\underset{|}{Cl}}{C}=CH-C{H}_{2}}$$

(b) PHBV $$\rightarrow$$ It is obtained by the copolymerisation of $$3$$-hydroxybutanoic acid and $$3$$-hydroxypentanoic acid.

$$\underset{\left( \text{3-Hydroxybutanoic acid} \right)}{C{H}_{3}-\overset{\underset{|}{OH}}{CH}-C{H}_{2}-COOH}$$ and $$\underset{\left( \text{3-Hydroxypentanoic acid} \right)}{C{H}_{3}-C{H}_{2}-\overset{\underset{|}{OH}}{CH}-C{H}_{2}-COOH}$$

(c) Bakelite $$\rightarrow$$ The monomeric unit present is formaldehyde and phenol.

$$\underset{\left( \text{Phenol} \right)}{{C}_{6}{H}_{5}-OH}$$ and $$\underset{\left( \text{Formaldehyde} \right)}{HCHO}$$


Write down difference between terylene fibre and Buna -S- rubber (elastomers).

Difference between terylene fibre and Buna-S rubber $$\rightarrow$$
  1. Terylene is a condensation polymer while Buna-S is an addition polymer.
  2. Terylene has stronger intermolecular forces of attraction as compared to Buna-S.


Give an example of each of homopolymer and copolymer.

Poly ethylene or PVC or PVA-Homo polymer
Poly ester or Terylene or Nylon-66- Co-polymer


Write chemical reactions to prepare the Nylon-6 polymers:


1213941_1561034_ans_c55afd5a4175416e859294778e15816f.png


Give an example of elastomers.


1657301_1570804_ans_a25867618c92455a9e1fa87096465055.jpg


Write the name of monomer unit of polymer used in non-stick surface coated utensils.

Tetrafluoro ethylene or Teflon($$CF_2=CF_2$$) is the name of monomer unit of polymer used in non -stick surface coated utensils.


Write chemical reactions to prepare the Teflon polymers:


1213939_1561029_ans_b2a6c80869d740e8b10a5b9e4fd8268e.png


Fill in the blanks :
A plastic bakelite is a compound of $$HCHO$$ with 


1655017_1720598_ans_7d0ca93532ba46ecb6f79df743fc54a0.png


Fill in the banks.
MonomersPolymersOther important use
.............Teflon...............

Monomer :- Tetrafluroethene
Use:- Manufacture of insulators.


Fill in the blanks.
Bakelite is made by the action of ...... and ...... 

Bakelite is made by the action of phenol  and formaldeyde. 


Fill in the banks.
MonomersPolymersOther important use
Formaldehyde, phenol..........................

This phenol-formaldehyde resin is a thermosetting polymer.
The important uses of this it can be used in manufacturing electrical switches and machine parts of electrical systems. 


Fill in the banks.
MonomersPolymersOther important use
.........................For making crockery

Monomers:- Malamine, formaldehyde.
Polymers:-Melamine formaldehyde resin


Write the name and structure of the monomer of natural rubber polymers.

The name of monomer of natural rubber is isoprene.
1609458_1721204_ans_c5f4bda48e4b4fbaa46e525e6cbae337.PNG


Write the names and structures of the monomers of Bakelite.

Monomers of Bakelite are Phenol and formaldehyde.
1609645_1721219_ans_0a25a465e5894ab9a71c1adfda0537a4.PNG


Describe how Bakelite is synthesised?

It is synthesised by the heating of phenol [$$C_6H_5OH$$] and formaldehyde [$$HCHO$$] in the presence of a catalyst such as hydrochloric acid, zinc chloride, or the base ammonia. 

1609824_1721261_ans_18e927048bed4a0f9d8dd17181cb2cc8.PNG


Write the names and structures of the monomers of synthetic rubber.

Synthetic rubbers are made from various petroleum-based monomers. The most prevalent synthetic rubber is styrene-butadiene rubbers (SBR) derived from the copolymerization of styrene and 1,3-butadiene. 

1609516_1721207_ans_c7f51dbfe28245b0a9915838dec55cd1.PNG


Fill in the banks.
MonomersPolymersOther important use
...............PMMA...............

Monomers:- Methyl methylacrylate.
Uses:- For making eye lenses


Can enzyme be called a polymer?

Yes, enzymes are biocatalysts which are proteins and are thus polymers. 


Why are rubbers called elastomers?

Rubbers are stretched on application of force and regain original state after the force is removed. Therefore, these are called elastomers. 


Name a synthetic polymer which is an amide. 

A synthetic polymer which is an amide is Nylon-6, 6. 


Write equations for the synthesis of Teflon.


1649050_1782174_ans_28a76f504fb24000a1c7f4b73e828798.png


Differentiate the following pair of polymers based on the property mentioned against each. 
Q. Novolac and bakelite (structure)

Novolac is a straight chain linear polymer but bakelite is cross linked. 


What are LDPE and HDPE? How are they prepared?

LDPE (Low Density Polyethylene): LDPE is obtained by the polymerisation of ethene under high pressure of 1000-2000 atm at 350-570 K in the presence of an initiator. 

HDPE (High Density Polyethylene): It is obtained when polymerisation is done in the presence of Ziegler-Natta catalyst at 333-343K under 6-7 atm pressure.


Why should the monomers used in addition polymerisation through free radical pathway be very pure?

Pure monomers are required because even the traces of impurities may act like inhibitors which leads to the formation of polymers with shorter chain length. 


Give the structure and name of the polymer which is used for making non-stick utensils. 


1649040_1782118_ans_cfd8ccbabfdb4bd780a5821a5ae4f6ae.png


Write names of monomer/s of the following polymers and classify them as addition or condensation polymers. 
i. Teflon
ii. Bakelite
iii. Natural Rubber 

Polymers   Type     Monomer
(i)Teflon   Addition     Tetrafluoroethene
(ii)Bakelite   Condensation     Phenol and formaldehyde
(iii)Natural rubber   Addition     cis-isoprene


Which type of biomolecules have some structural similarity with synthetic polyamides? What is this similarity?

Proteins have structural similarity with synthetic polyamides. Polyamides and proteins both contain amide linkage. 


A monomer of a polymer upon ozonolysis gives one mole of methylglyoxal and two moles of formaldehyde. 
i. Identify the monomer of the polymer. 
ii. Give its free radical mode of addition polymerisation. 

As the monomer on ozonolysis gives one mole of methylglyoxal and two moles of formaldehyde, therefore, the monomer is isoprene. 
1649087_1782357_ans_fa16416b82ec456e80a1663e55d40a3d.png


How does vulcanisation change the properties of natural rubber?

Rubber gets cross-linked through S-S bonds and becomes hard on vulcanisation. 


Define step growth polymerisation. 

Step growth polymerisation involves a series of condensation reactions between simple monomers containing polar groups, with or without the elimination of small molecules like water, HCl, NH$$_{3}$$, etc. In addition to carbon atoms, these polymers contain other atoms also in their main chain. 


Identify the type of polymer given in the following figure.
1797140_23f266962b0f40f4b5b6f30509222cd0.png

Cross-linked of Network polymers: These are usually formed from bi-functional and trifunctional monomers and contain strong covalent bonds between various linear polymer chain i.e. Bakelite melamine, etc.


What is the role of sulphur in the vulcanisation of rubber?

On vulcanisation, sulphur forms cross-links at the reactive sites of the double bond and thus rubber gets stiffened. 


Why are rubbers called elastomers?

Rubber is a natural polymer and possesses elastic properties. It is also termed as elastomer and has a variety of uses. It is manufactured from rubber latex which is a colloidal dispersion of rubber in water.


Why does cis-polyisoprene possess elastic property?

The cis-polyisoprene molecule consists of various chains held together by weak can der Walls interactions and has a coiled structure. Thus, it can be stretched like a spring and exhibits elastic properties.


What are polymer ?

The synthetic fibres made from small units which combines to form long chain are called $$polymer$$. 


Thermocol melts at .............. $$^{ o }{ C }.$$

It is a kind of thermoplastic material. And all the thermoplastic materials have a melting point range of 210°C -250°C. And similarly, thermocol melting point also belongs in this range. The average melting point of the thermocol in normal conditions is almost 240°C.

Hence, we can say:
Thermocol melts at more than $$100^{0} C.$$


Write short notes on the following:
Natural rubber

Natural Rubber: This is obtained from latex which is a sap of a tree. Natural rubber is a polymer of isoprene.
Acetic acid is added to latex to make it solid. Rubber obtained by this process is highly elastic and has less tensile strength. This is not suitable for making useful products. To make it useful, the rubber is heated with sulphur and the process is called vulcanization. Rubber obtained after vulcanization is strong, inelastic, and more durable.


Can nucleic acids, proteins and starch be considered as step growth polymers?

Yes, this of polymerization generally involves a repetitive condensation reaction between two bi-functional monomers. These polycondensation reactions may result in the loss of some simple molecules as water, alcohol, etc. and lead to the formation of high molecular mass condensation polymers.


Define polymers?

Polymers are high molecular mass ($$\mathrm{10^3 - 10^7 \ u}$$) substances consisting of a very large number of simple repeating structural units joined together through covalent bonds in a linear fashion. 
Example: Polythene, Nylon –$$6,6$$, Bakelite, etc.


Select an appropriate chemical bond among ester bond, glycosidic bond, peptide bond and hydrogen bond and write against of the following.
Water


2127449_1842725_ans_1c79042f773c43e9abcb8a298e4d4eac.jpg


 Polymers are macromolecules formed by the combination of many monomers.
a. How are polymers classified?
b. Classify the following: Cotton, Wool, Nylon, Silk, Terylene, Jute, Polyester

a. Polymers are classified
i. On the basis of its formation as natural and man-made. 
ii. On the basis of structure as linear branched-chain, cross-linked chain 
iii. On the basis of process as addition polymer and condensation polymer. 
iv. On the basis of molecular strength as fibres and plastics 

b. Natural: wool, silk, jute, cotton 
Man-made: Nylon, Terylene, Polyester 


Write short notes on the following:
Polyacrylo nitrile

Polyacrylo nitrile: This is obtained by polymerization of vinyl cyanide. It is used for making a sweater, wool-like fiber, pillow, quilt, etc.
1724587_1822582_ans_9bdf7d54782547068c7bb965248030dd.png


Separate natural and artificial polymer from the list Rubber, wool, Pvc, Bakelite, nylon, rayon cellulose, silk, polythene, polyester 

NaturalArtificial
RubberP.V.C.
WoolPolythene
Cellulose         Nylon
SilkRayon
Polyester


If we heat polyethene cover can we convert into earlier stage? Justify.

No, because formation of plastic is a chemical change and it can't be reversed.


Find out odd one and give reason. Bakelite, polyester, polythene, melamine formaldehyde.

Polythene is odd one out because it is a thermoplastic rest all the others are thermosetting plastics. 


Give four difference between natural rubber and synthetic rubber.

1. Synthetic rubber is harder than natural rubber. 
2. Natural rubber is easily flammable. 
3. The elasticity of natural rubber is lower than that of synthetic rubber. 
4. Synthetic rubber keeps stability at higher temperature. 


What is teflon? What is it used for?

Teflon is the trade name for a plastic material called polytetrafluoroethylene.

It is used for making non-sticky utensils.


Filling in the blanks.
Natural polymer is __________.

Natural polymer is Starch.


Filling in the blanks.
Natural polymer which has elastic nature is ______.

Natural polymer which has elastic nature is Rubber.


Filling in the blanks.
Polymers of plant origin are made up of ________.

Polymers of plant origin are made up of cellulose .


Match list I with list II. Matching can be one or more than one.

Number-average molecular mass $$(M\overline{n})$$ is given by the expression $$\frac {\sum NiMi}{\underset{i}{\sum } Ni }$$.
Weight-average molecular mass $$(M\overline{w})$$ is given by the expression $$\displaystyle \frac {\sum NiMi^2}{\underset{i}{\sum } NiMi }$$.
Z-average molecular mass $$(M\overline{z})=$$ $$\frac {\sum NiMi^3}{\underset{i}{\sum } NiMi^2 }$$.
Polydispersity index (PDI) is $$\displaystyle \frac{M\overline{w}}{M\overline{n}}$$.


Match the plastic given in list I with its corresponding uses given in list II.

The use of the polymers based on their properties are given below:

Polythene - for making covering from protection from rain as it does not allow water to pass through it.

PVC-for making rain coats, water pipes, pipe fitting and body of automobile batteries.

Teflon- for coating in cooking utensils and non- stick pan.

Bakelite- PVC-for making electric switches and handles for cooking utensils as it is thermo-setting plastic and it does not melt on heating.

PET- for making bottle, jars and thin films.

Melamine- for making uniform of fire man fire resistant.


Explain the term copolymerisation and give two examples.

Copolymerisation is a process in which a mixture of more than one monomeric species is allowed to polymerise. The copolymer contains multiple units of each monomer in the chain. The examples are copolymers of $$1,3$$-butadiene and styrene, hexamethylene diamine and adipic acid (Nylon-$$6,6$$) and $$1, 3$$-butadiene and acrylonitrile.
471011_453724_ans_2f7fdf817655498a8019054ffe31f933.png


How does the presence of double bonds in rubber molecules influence their structure and reactivity?

Natural rubber is a linear. It is cis-$$1,4$$- polyisoprene. The double bonds are located between $$C_2 $$ and $$C_3$$ of isoprene units. This cis-configuration about double bonds do not allow the chains to come closer for effective attraction due to weak intermolecular attractions. Hence, the natural rubber has a coiled structure and shows elasticity.
469260_453741_ans_1e82576ab04542a9959dbeded9c96c54.png


Match the List 1 with List 2 and choose the correct option.

PVC is polyvinyl chloride and is used to produce synthetic plastic polymer. It is of two forms rigid and flexible.

Teflon is polytetrafluoroethylene. It is used as a non-stick coating for pans and it is non-reactive.

Melamine is 1,3,5-triazine. It is combined with formaldehyde to produce melamine resin and melamine foam is used as THERMAL insulation material.

Bakelite is a thermosetting phenol formaldehyde resin formed from the elimination reaction phenol and HCHO.

The correct match is A-3, B-4, C-2 D-1


Study the given flowchart carefully. $$K,\,L,\,P\;and\;Q$$ plastics are
$$\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;K\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;L\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;P\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;Q$$
(A)$$\;\;\;\;$$Polystyrene,$$\;\;\;\;\;$$Bakelite,$$\;\;\;\;\;\;\;\;\;\;\;$$Teflon,$$\;\;\;\;\;\;\;\;\;\;\;$$PVC
(B)$$\;\;\;\;\;$$Polythene,$$\;\;\;\;\;$$Polystyrene,$$\;\;\;\;\;\;\;$$Bakelite,$$\;\;\;\;\;\;\;\;$$PVC
(C)$$\;\;\;\;$$PVC,$$\;\;\;\;\;\;\;\;\;\;\;\;\;\;$$Polythene,$$\;\;\;\;\;\;\;\;\;\;$$Polystyrene,$$\;\;\;$$Bakelite
(D)$$\;\;\;\;$$PVC,$$\;\;\;\;\;\;\;\;\;\;\;\;\;\;$$Teflon,$$\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;$$Melamine,$$\;\;\;\;\;$$Bakelite

Choose your answer from A, B, C and D and enter accordingly.

313999.png

K- PVC is polyvinyl chloride and is used to produce synthetic plastic polymer. It is of two forms rigid and flexible.

L- Teflon is polytetrafluoroethylene. It is used as non stick coating for pans and it is non reactive.

P-Melamine is 1,3,5-triazine. It is combined with formaldehyde to produce melamine resin and melamine foam is used as insulation material.

Q- It is a thermosetting phenol formaldehyde resin formed from elimination reaction phenol and HCHO.

$$\;\;\;\;\;\;\;\;\;\;\;K\;\;\;\;\;\;\;\;\;\;\;\;L\;\;\;\;\;\;\;\;\;\;\;\;\;P\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;Q$$
(D)$$\;\;\;\;$$PVC,$$\;\;\;\;\;\;$$Teflon,$$\;\;\;\;\;$$Melamine,$$\;\;\;\;\;$$Bakelite


Identify the monomer in the above polymeric structures.
453756_415aa7b9a2b449b09d0f51f4462d4ef6.png

i)In the first case, the polymer given is Nylon 6,10 and the monomers are decanoic acid, $$\displaystyle HOOC-(CH_2)_8COOH$$ and hexamethylene diamine, $$\displaystyle NH_2-(CH_2)_6-NH_2$$.

(ii) In the second case, the monomers are formaldehyde and melamine whose structures are given above.

469326_453756_ans_f77bbd05c53a4bb4b1053e421c724502.png


How is dacron obtained from ethylene glycol and terephthalic acid ?


Dacron is obtained by the condensation polymerisation of ethylene glycol and terephthalic acid.
It is an example of polyester. The balanced equation is as shown.
469301_453771_ans_24f7bf4d7e0c4e31b283ca90882e5974.png


Explain the following terms giving a suitable example for each.
(i) Elastomers    
(ii) Condensation polymer   
(iii) Addition polymers

(i) Elastomers:
They have the weakest attraction force in between polymeric chains. Hence, they are amorphous with a high degree of elasticity. They have the ability to stretch out over ten times the original length and get back to their original position after removing the force. 
For example, Buna-S, Buna-N, Neoprene

(ii) Condensation Polymerization:
When both reactants of a chemical reaction are bi-functional, they undergo a series of condensation reactions and form a polymer chain. This type of polymerization is called condensation polymerization. The condensation polymerization takes place in a stepwise manner with the loss of simple molecules like water, carbon dioxide, alcohol, $$HCl$$, etc.
Condensation polymerization starts from the condensation reaction of two reactant molecules and forms a dimer.

For example, condensation polymerization of terephthaloyl chloride and ethylene glycol forms a polyester known as poly (ethylene terephthalate) by the elimination of hydrochloric acid.

(iii) Addition Polymerization:
Monomer units, added to grow a polymer chain caring a reactive intermediate like free radical, carbocation or carbanion, is known as addition polymerization. Since it forms a long polymer chain, it is also known as chain-growth polymerization.
For example, ethene $$(H_2C = CH_2)$$ is polymerized for polythene. 


Polymers are macro molecules formed by union of monomers.
(a) Name natural polymer and synthetic polymer.
(b) Distinguish between thermoplastic and thermosetting polymers with examples.

a) Natural polymers: The polymers obtained naturally are called natural polymers. A natural polymes are obtained from plants and animals. Starch, cellulose, proteins, natural rubber etc. are the examples of natural polymers.

Synthetic polymers: These are man-made polymers or the polymers which are synthesized in the laboratory are called Synthetic polymers. Examples of synthetic polymers are polyethylene, polyvinyl chloride, nylon, synthetic rubbers.

b) Thermoplastic polymer  can be melted and reshaped again and again. These are addition polymers  while thermosetting plastics can only be heated and shaped once. Items made from thermoplastics can easily deform when they are exposed to heat, while those that are made of thermosetting plastics cannot.



What are carbohydrates?  Write the reaction for the preparation of Nylon-$$6$$.

Carbohydrates are optically active polyhydroxy aldehyde or polyhydroxy ketones or the compounds that can be hydrolysed to polyhydroxy aldehyde or polyhydroxy ketones are called as carbohydrates.
The image explains the prepration of Nylon-6. In this reaction, caprolactum gives Nylon-6 on polymerimization.

628450_601960_ans.png


a) Write partial structure of:
   i) Neoprene
   ii) Terylene (Dacron)
   iii) Nylon - 6
b) Explain the preparation of Buna-N with equation

$$\displaystyle Buna-N$$ is a copolymer of acrylonitrile and
$$\displaystyle 1,3$$-butadiene. It is prepared by addition polymerisation.
658131_623472_ans_ebd6c8da890b46e0936f1768bc80e2be.png


Why bakelite does not become soft on heating?

  • There are 2 types of plastics : thermosets and thermoplastics. 
  • Thermoplastics can be reshaped on heating whereas thermosets cannot be reshaped.
  • Bakelite is a thermosetting plastic. Hence, it cannot be reshaped on heating. 


Write down the chemical equation for the preparation of Bakelite from formaldehyde?

The chemical equation for the preparation of Bakelite from formaldehyde is as shown.

776975_761238_ans_93233d88f8a9491ea6024780fb375d97.png


How is Teflon prepared? Give chemical equation?

Teflon (PTFE or polytetrafluoroethylene) is prepared by addition (chain growth) polymerisation of tetrafluoroethylene.
$$ \displaystyle n F_2C=CF_2 \xrightarrow [\text {heat}]{\Delta} \underset {  \displaystyle  \text { Teflon } }{ -(F_2C-CF_2)-_n}$$
Thus, the monomer used is tetrafluoroethylene ($$ \displaystyle  F_2C=CF_2 $$).


Give chemical equations for the following conversions:
(i) Ethylene into polythene
(ii) Ethyl alcohol into iodoform

Give chemical equations:
(i) Ethylene into polythene
$$ \displaystyle   \underset {  \displaystyle  \text { ethylene  } }{ \quad n{ C }_{ 2 }{ H }_{ 4 }} \xrightarrow [    \displaystyle  

 \text {  200-300 deg C, 1000 atm, } O_2   \text { catalyst} ]{  \displaystyle    \text {  Polymerisation} } \underset {  

\displaystyle    \text {  Polythene}  }{ { \left( { C }_{ 2 }{ H }_{ 4 } \right)  }_{ n } } $$

(ii) Ethyl alcohol into iodoform
$$  \displaystyle \underset {  \displaystyle  \text {  Ethyl alcohol } }{  { C }_{ 2 }{ H }_{ 5 }OH}+4{ I }_{ 2 }+6NaOH\longrightarrow \underset { \displaystyle \text { Iodoform }}{ { CHI }_{ 3 } }

+HCOONa+5NaI+5{ H }_{ 2 }O\quad $$


Very short answer type.
Name the monomer(s) of the following dimers/polymers proteins 

Proteins are composed of amino acids. Protein is a large molecule composed of large chains of amino acids.


Why did Shyam refuse to accept the items in polythene bags?

Shyam refused to accept the items in polythene bags because  the government had imposed heavy penalty for using polythene bags. This penalty is due to the fact that polythene bags are made from non-biodegradable polymers which cause environmental pollution.


Very short answer type.
Name the monomer(s) of the following dimers/polymers sugar 

Sugar or sucrose is a disaccharide composed of glucose and fructose as monosaccharides.


How does the presence of benzoquinone inhibit the free radical polymerisation of a vinyl derivative?

In the free radical polymerization of vinyl derivative, a reactive intermediate($$R^*$$) is formed which is responsible for the further progress of the chain reaction. Benzoquinone traps this reactive intermediate radical and changes it into non-reactive radical by stabilising it through resonance. In the absence of this reactive intermediate, further progress of the chain reaction is stopped.
1105446_1134832_ans_eba5d75afcdc4121a4f3e02e0ced3f66.png


Write a note on vulcanization of rubber.

Vulcanization of rubber is a process of improvement of the rubber elasticity and strength by heating it in the presence of sulfur, which results in three-dimensional cross-linking of the chain rubber molecules (polyisoprene) bonded to each other by sulfur atoms



How is Orlon prepared?

Orlon is polymer of vinyl cyanide.It is made by addition of acryolnitrile molecules. It is a brand of synthetic, acrylic textile fibre of light weight and wrinkle resistant fabric.


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Name the polymer which is used for making non-stick utensils.

PTFE (Poly tetra fluoro ethylene) is the polymer used for making non sticky utensils because it is highly inert and don't react with other substances easily.


Identify the monomers in the following polymers :
1700651_2c72589a41a74a46a1caa79475c27a95.png

Given polymers 
Ref. image I
Above polymer is known as novolac which is result of polymerization of phenol with formaldehyde.
So,
Its monomers are
Ref. image II 
1499448_1700651_ans_a426449e1853448c928995069beb618a.png


Write the short notes on the following:
(a) Co-polymer,
(b) Synthetic rubber,
(c) Thermoplastic,
(d) Thermosetting,
(e) Elastomer,
(f) Vulcanization of rubber

(a) Co-Polymer:

A copolymer is a polymer that is produced by the copolymerization of two or more different monomers. Many commercially important polymers are copolymers. Examples include polyethylene-vinyl acetate (PEVA), nitrile rubber, and acrylonitrile butadiene styrene (ABS).

Properties: General properties of copolymers include their ability to be thermoplastic or thermoset and elastic. Other properties include a copolymer's ability to be chemical resistant. Chain length and branching influence the strength of a copolymer chain.

Applications: Copolymerization is used to modify the properties of manufactured plastics to meet specific needs, for example, to reduce crystallinity, modify glass transition temperature, control wetting properties, or to improve solubility. It is a way of improving mechanical properties, in a technique known as rubber toughening.


(b) synthetic rubber :

Synthetic rubber is any artificial elastomer. These are mainly polymers synthesized from petroleum byproducts. Among the most important synthetic rubbers are butadiene rubber, neoprene, styrene-butadiene rubber, the polysulfide rubbers (thiokols), butyl rubber, and silicones.

Properties: synthetic rubber offers better resistance to abrasion than natural rubber, as well as superior resistance to heat and the effects of aging. Many types of synthetic rubber are flame-resistant, so it can be used as insulation for electrical devices.

Applications of Synthetic Rubber: The majority of rubber (natural or synthetic) is used to make tires. However, it's mixed with a filler agent like carbon black to make sturdy and tough tires. After tires, there is a variety of products where synthetic rubber is used like adhesives and latex gloves.


(c) Thermoplastic:

A thermoplastic is a material, usually a plastic polymer, which becomes softer when heated and hard when cooled. Thermoplastic materials can be cooled and heated several times without any change in their chemical or mechanical properties. When thermoplastics are heated to their melting point, they melt to a liquid.

Examples of thermoplastic materials are polyethylene, polypropylene, polyvinyl chloride, polystyrene, polyamides, polyesters, and polyurethanes. High-temperature thermoplastics include polyether ketones, liquid crystalline polymers, polysulfones, and polyphenylene sulfide.

Properties: Thermoplastics materials are highly recyclable. They offer aesthetically-superior finishes, They have High-impact resistance, They contain remolding/reshaping capabilities. They offer chemical resistance. They have a hard crystalline or rubbery surface options and have Eco-friendly manufacturing.

Applications: Extruded polystyrene (PS) is used in the manufacture of disposable cutlery, CD and DVD cases, plastic models of cars and boats, and smoke detector housings. Expanded polystyrene foam (EPS) is used in making insulation and packaging materials, such as the "peanuts" and molded foam used to cushion fragile products.


(d)Thermosetting:

Thermosetting plastic is a polymer that irreversibly becomes rigid when heated. Such a material is also known as a thermoset or thermosetting polymer. Heat provides energy for chemical reactions that increase the cross-linking between polymer chains, curing the plastic.

In contrast to thermoplastics, thermosets (alternately known as  thermosetting plastics or thermosetting polymers) are materials that remain in a permanent solid state after being cured one time. Common examples of thermoset plastics and polymers include epoxy, silicone, polyurethane, and phenolic.

Properties: The higher the crosslink density and aromatic content of a thermoset polymer, the higher the resistance to heat degradation and chemical attack. Mechanical strength and hardness also improve with crosslink density, although at the expense of brittleness. They normally decompose before melting.

Applications: Common products and applications that are made from thermoset plastics include construction equipment panels, electrical housings and components, insulators, cell tower tops, heat shields, circuit breakers, agricultural feeding troughs, motor components, and disc brake pistons.


(e)Elastomer:

Elastomers are loosely cross-linked polymers. Examples of elastomers include natural rubbers, styrene-butadiene block copolymers, polyisoprene, polybutadiene, ethylene-propylene rubber, ethylene propylene diene rubber, silicone elastomers, fluoroelastomers, polyurethane elastomers, and nitrile rubbers.

Properties: Elastomer properties include resilience — some elastomeric materials can be stretched repeatedly to twice their length and return to their original shape. They provide flexibility from their polymer composition, above the glass transition temperature (Tg) for end-use requirements, and don't melt in high temperatures.

Applications: Primary uses for elastomer are seals, molded flexible parts and adhesives, and used in vehicle manufacturing, food production, scientific applications, and chemical processes. Elastomer is available in different grades, depending on their application.

 

(f) Vulcanization of Rubber:

Vulcanization is a chemical process in which the rubber is heated with sulphur, accelerator, and activator at 140–160°C. The process involves the formation of cross-links between long rubber molecules so as to achieve improved elasticity, resilience, tensile strength, viscosity, hardness, and weather resistance.

Examples include silicone rubber via room temperature vulcanizing and  chloroprene rubber (neoprene) using metal oxides. 

Applications: Vulcanised rubber is used to manufacture all sorts of products today. Perhaps the best-known and most prevalent use of vulcanized rubber is vehicle tyres, which are commonly combined with the reinforcing agent carbon black for even greater strength. Other common vulcanized rubber uses include: Rubber hoses, Shoe hoses, Toys, Erasers, conveyor belts, Insulation, Vibration damps, Shock Absorbers etc.



Describe how Nylon-6 is synthesised?

When caprolactam is heated at about 533 K in an inert atmosphere of nitrogen for about 4-5 hours, the ring breaks and undergoes polymerization and form Nylon-6.

1610115_1721271_ans_7a86f41c277b4522a7c9846d083927ad.PNG


Match the following column-I with column-II

(A) Starch is made up of glucose monomer and joined by glycosidic bond and natural polymer.

(B) Nylon-6 is a synthetic polymer and have amide linkage

(C) Peptide bond is an amide linkage

(D) Maltose is a disaccharide(Oligosaccharide)


Name the sub-groups into which polymers are classified on the basis of magnitude of intermolecular forces. 


1659864_1782160_ans_b70dbfe3a1af4f918e2cfac9439ba950.jpg


Explain why free radical polymerisation of styrene gives a product in which phenyl groups are on alternate carbon atoms rather than on adjacent carbon atoms. 

During free radical polymerisation, the addition of free radical to monomer molecules occurs in accordance with Markovnikov's rule so as to give more stable benzylic free radical. 
For example, 
This process goes on till polystrene (V) in which the phenyl groups are on alternate carbon atoms is obtained rather than the product (VI) in which the phenyl groups are on adjacent carbon atoms. 
1649090_1782422_ans_fb0c505eaccc4de6ac5786c13692fac9.png


To have practical applications why are cross links required in rubber?

To improve upon the physical properties of natural rubber, a process of vulcanization is carried out. This process consists of heating a mixture of raw rubber with sulphur and an appropriate additive at a temperature range between $$373\ K$$ to $$415\ K$$. On vulcanization, sulphur forms cross-links at the reactive sites of double bonds, and thus the rubber gets stiffened.


What is the structural difference between $$HDP$$ and $$LDP$$? How does the structure account for different behavior and nature, hence the use of a polymer?

Low-density polythene: It is obtained by the polymerization of ethane under high pressure of $$1000$$ to $$2000$$ atmospheres at a temperature of $$350\ K$$ to $$570\ K$$ in the presence of traces of dioxygen or a peroxide initiator (catalyst). The low-density polythene $$(LDP)$$ obtained through the free radical addition and $$H-$$ atom abstraction has a highly branched structure.
High-density polythene: It is formed when addition polymerization of ethane takes place in a hydrocarbon solvent such as triethyl aluminium and titanium tetrachloride (Ziegler-Natta catalyst) at a temperature of $$333\ K$$ to $$343\ K$$ and under a pressure of $$6-7$$ atmospheres. High-density polythene $$(HDP)$$ thus produced, consists of linear molecules and has a high density due to close packing. It is also chemically inert and tougher and harder. It is used manufacturing buckets, dustbins, bottles, pipes.


Why has the use of methods like Teflon coating become more common ?

Teflon is a substance which is inert to chemicals, stable at higher temperatures, easy to clean and non stick. All these properties make it an ideal substance for coating.


Fill in the blanks :
The chemical name of Teflon is ......

The chemical name of Teflon is polytetrafluoroethene 


In free radical polymerization, where do we use hydroquinone? Explain.

Benzoquinone combines with free-radical intermediate to form of non-reactive radical, which is highly stabilized by resonance.
1751951_1832278_ans_031e2840e52447feb290c0a0558368d0.png


Write down properties of teflon.

Teflon has the following properties:
  • it is inert to the atmosphere and chemical substances
  • both water and oil do not stick to the teflon coated articles
  • it has a high melting point i.e. $$ 327^{\circ} \,C $$ which means there is no effect of high temperatures on it
  • it is easier to clean teflon coated articles


Write some properties and use of melamine .

$$Melamine$$ is a $$versatile$$ $$material$$. It $$resists$$ fire and can tolerate heat better than other plastic. 
$$It$$ $$used$$ for making floor tiles, Kitchenware, and fabric which resists fire.


Low-density polythene and high-density polyethylene, both are polymers of ethane but there is marked difference in their properties. Explain.

$$LDP$$$$HDP$$
It is obtained the polymerization of ethane under high pressure of $$1000$$ to $$2000$$ atmospheres at a temperature of $$350\ K$$ to $$570\ K$$ in the pressure of traces of dioxygen or a peroxide initiator.It is formed when addition polymerization of ethane takes place in a hydrocarbon solvent in the presence of a catalyst such as triethylaluminium and titanium tetrachloride at a temperature of $$333\ K$$ to $$343\ K$$ and under a pressure of $$6-7$$ atmospheres.
$$(LDP)$$ obtained through the free radical addition and $$H-$$atoms abstraction has a highly branched structure.$$(HDP)$$ consists of linear molecules and has a high density due to close packing.
Low-density polyethylene is chemically inert and tough but flexible and a poor conductor of electricity.It is also chemically inert and more tough and hard.


What does PMMA stand for ?

Poly (methyl methacrylate)


How many methods of chain termination are there in the free radical mechanism?

There are three methods of chain termination in a free-radical mechanism:
1) Coupling
2) Disproportionation
3) Chain Transfer


What do LDPE and HOPE indicate? How are they formed?

Low-Density Polyethylene (LDPE): It is obtained by heating very pure ethylene at $$350\, K – 570\, K$$ under a pressure of about $$1500$$ atm in the presence of traces of oxygen. It is a highly branched polymer. It is chemically inert, tough but flexible. It is used for packing, cable insulation, and in the manufacture of pipes, toys, etc. 

High-Density polyethene (HDPE): It is obtained by polymerization of ethylene at about $$333 - 343\, K$$ under $$6$$ to $$7$$ atmospheric pressure in the pressure of catalysts such as triethyl aluminum and titanium tetrachloride. It is chemically inert having greater toughness and hardness.


What is PHBV?

Polyhydroxybutyrate – Co – $$\beta$$ – hydroxy valerate (PHBV) is used in especially packing. Orthopedic devices and in controlled release of drugs. PHBV undergoes bacterial degradation in the environment.


Uses of some important organic compounds are given. Pick out the suitable compounds from the box.

Power alcohol, Teflon, Polythene, Ethanoic acid, Ethanol

A) Solvent in paint industry

Methanol is a good solvent. Paints and varnishes dissolve in it. Hence, methanol is used as a solvent for paints and varnishes.


What is an addition polymerization? Explain the free radical addition polymerization mechanism by taking an example.

Addition polymerization:
A polymer formed by direct addition of repeated monomer molecules possessing double or triple bond, without the elimination of any small molecule is called addition polymerization.
Example: polythene, PVC, etc.
Mechanism of free radical addition is completed in three parts:
1752288_1832317_ans_9eb1ae12597d4d45808fc5036b126986.png


Write the method of polymerization and uses of bakelite.

Bakelite:
It is condensation polymer and is obtained from phenol and formaldehyde in the presence of either an acid or a base catalyst.

Uses:
Soft Bakelite with low degree polymerization is used for making glue for binding laminated wooden planks and varnishes, High degree polymerization gives hard bakelite which is making combs, fountain pens, barrels, electrical switches, etc.


How natural rubber is obtained? Write its composition and structure.

To obtain natural rubber first of all latex or rubber plant is obtained. The latex contains, about $$25 – 40\%$$ of rubber hydrocarbons dispersed in water along with stabilizer proteins, and some fatty acids are mixed due to which rubber coagulates and precipitated out. It is separated by filtration. This rubber is known as crepe rubber.

Structure and composition:
Natural rubber may be considered as a linear polymer of isoprene ($$2$$ – methyl –$$1, 3$$ butadiene) and also called as cis –$$1,4$$ polyisoprene.

1752291_1832319_ans_1e4377459bd54a23b9ebd55844ade0da.png


Write a short note on biopolymers and biodegradable polymers.

1. Biopolymers: Many polymers that are present in plants and animals such as polysaccharides (starch, cellulose), proteins and nucleic acid, etc. which control various life processes in plants and animals are called biopolymers. Examples: Protein, Carbohydrates, Nucleic acid, Lipids, etc. 

2. Biodegradable: The polymers which are degraded by microorganisms within a suitable time period so that the polymers and their degraded products do not cause any serious effects on the environment are called biodegradable polymers. Example: polylactic acid (PLA), Polyglycolic acid (PGA) and PHB, etc.


When we talk of functional macromolecules (e.g. proteins as enzymes, hormones, receptors, antibodies, etc), towards what are they evolving?

Functional macro-molecules are evolving towards living forms.


Class 12 Engineering Chemistry Extra Questions