Chapter 13 Polymer
Multiple Choice Questions (MCQs)
1. Which of the following polymers of glucose is stored by animals?
(a) Cellulose
(b) Amylose
(c) Amylopectin
(d) Glycogen
Answer (d) Glycogen is a polymer of glucose found in liver, brain and muscles of animals. Cellulose is a polymer found in plant while amylose and amylopectin are structural units of starch.Show Answer
(a) cis-polyisoprene
(b) Cellulose nitrate
(c) Cellulose acetate
(d) Vulcanised rubber
Answer (a) cis-polyisoprene is not a semisynthetic polymer while other three cellulose nitrate, cellulose acetate and vulcanised rubber are semisynthetic polymer made from cellulose, cellulose and natural rubber respectively.Show Answer
(a) dacron
(b) orlon (acrilan)
(c) PVC
(d) bakelite
Answer (b) The commercial name of polyacrylonitrile is orlon (acrilan).Show Answer
Answer (c) Poly $\beta$ - hydroxybutyrate - co- $\beta$ - hydroxy valerate is an example of biodegradable polymer.Show Answer
Answer (a) Given polymer can be obtained condensation polymerisation of ethylene glycol and phthalic acid with the elimination of water molecule.Show Answer
(a) Tough
(b) Hard
(c) Poor conductor of electricity
(d) Highly branched structure
Answer (d) Low density polythene has slightly branched but not highly branched structure.Show Answer
Answer can be obtained by addition polymerisation of shown belowShow Answer
(a) Nylon-6, 6
(b) Nylon-2-nylon-6
(c) Melamine polymer
(d) Nylon-6
Show Answer
Answer
(d) Given, monomer is the structure of caprolactum which on polymerisation produces Nylon-6.
Multiple Choice Questions (More Than One Options)
9. Which of the following polymers, need atleast one diene monomer for their preparation?
(a) Dacron
(b) Buna-S
(c) Neoprene
(d) Novolac
Answer ( $b, c$ ) Buna-S and neoprene are two such polymers which needs atleast one diene monomer for their preparation. (b) Buna-S is prepared by copolymerisation of 1, 3-butadiene and styrene. (c) Neoprene is prepared by polymerisation of chloropreneShow Answer
(a) Heavily branched cross linked polymers
(b) Linear slightly branched long chain molecules
(c) Become infusible on moulding so cannot be reused
(d) Soften on heating and harden on cooling, can be reused
Answer (a, c) Thermosetting polymer (i) These are cross linked or heavily branched molecule. (ii) These on heating undergo extensive cross linking in moulds and become infusible (iii) These cannot be reused. (iv) Examples are bakelite, urea-form aldehyderesin.Show Answer
(a) Teflon
(b) Natural rubber
(c) Neoprene
(d) Polystyrene
Answer $(a, d)$ Thermoplastic polymer (i) These are linear or slightly branched long chain molecules. (ii) These polymers are hard at room temperature, become soft and viscous on heating and again rigid on cooling. This process of heat softening and hardening on cooling can be repeated as many times and as desired without any change in chemical composition.Show Answer
(a) Polytetrafluoroethane
(b) Polychloroprene
(c) Nylon
(d) Terylene
Answer (c, d) Nylon and terylene are used as fibre due to strong intermolecular forces like $\mathrm{H}$-bonding which lead to close packing in chain and thus impart crystalline nature.Show Answer
(a) Nylon
(b) Melamine formaldehyde resin
(c) Orlon
(d) Polystyrene
Answer (c, d) Addition polymers are formed by the repeated addition of a large number of same or different monomers possessing double and triple bonds. e.g., (i) Orlon is obtained by addition polymerisation of acrylonitrile in presence of a perovide catalyst. (ii) Polystyrene is obtained by addition polymeriration of styrene.Show Answer
(a) Bakelite
(b) Teflon
(c) Butyl rubber
(d) Melamine formaldehyde resin
Answer $(a, d)$ Condensation polymers are formed by repeated condensation reaction between two bifunctional or trifunctional monomer units usually with the elimination of small molecules like water, alcohol, ammonia, $\mathrm{CO} _{2}, \mathrm{HCl}$. e.g., (i) Bakelite is obtained by polymeristation of phenol and formaldehyde. (ii) Melamine-formaldehyde resinShow Answer
(a) 3-hydroxybutanoic acid + 3-hydroxypentanoic acid
(b) Glycine + amino caproic acid
(c) Ethylene glycol + phthalic acid
(d) Caprolactum
Answer ( $a, b$ ) Biodegradable Polymer The polymers which are easily decomposed and not harmful for the environment are known as biodegradable polymer. e.g., (i) PHBV is obtained by condensation polymerisation of 3 hydroxybutanoic acid and 3 hxydroypentanoic acid. (ii) Glycine and aminocaproic acid produces nylon-2 nylon-6 polymer.Show Answer
(a) Polychloroprene
(b) Polyacrylonitrile
(c) Buna-N
(d) cis-polyisoprene
Answer $(a, c)$ Synthetic Polymer Polymer which are not found in nature and can be synthesised in laboratory and industry are known as synthetic polymer. e.g., (i) Polychloroprene also known as neoprene is a polymer of chloroprene [monomer].
(ii) Buna- $\mathrm{N}$ can be obtained by copolymerisation of 1, 3-Butadiene and acyrlonitrile as shown belowShow Answer
(a) Nylon
(b) Polystyrene
(c) Rubber
(d) Polysters
Answer $(a, d)$ Nylon and polyesters have strong intermolecular forces of attractions due to presence of ether $\mathrm{H}$-bonding or dipole-dipole interactions.Show Answer
(a) Acrilan
(b) Polystyrene
(c) Nylon
(d) Teflon
Answer $(a, b, d)$ Acrilan, polystyrene and teflon has vinylic monomer units as shown below.
Show Answer
(a) more elastic
(b) soluble in inorganic solvent
(c) crystalline
(d) more stiff
Show Answer
Thinking Process
This problem includes the concept of vulcaniztion of rubber and characteristic of vulcanized rubber. Vulcanization of rubber produces more elastic and more stiff rubber due to presence of sulphide linkage.
Answer
$(a, d)$
In vulcanized rubber, the polymer chains are held together by sulphur cross- linkages ( - S-S - ). These cross links make rubber more hard, elastic and stronger.
Short Answer Type Questions
20. A natural linear polymer of 2-methyl-1, 3-butadiene becomes hard on treatment with sulphur between 373 to $415 \mathrm{~K}$ and - S-S-bonds are formed between chains. Write the structure of the product of this treatment?
Thinking Process This problem is based on vulcanized rubber and its structure. Answer The product is called vulcanised rubber. Its structure isShow Answer
$$ -A-A-A-A-A-A- $$
Answer Homopolymer as it contains only one type of monomer units. i.e., only A monomer units.Show Answer
$$ -A-B-B-A-A-A-B-A- $$
Answer Copolymer, as it contains more than one type of monomer units. Here, $A$ and $B$ are two types of monomer units.Show Answer
Answer Chain growth polymerisation, as there is no loss of small molecules like water; methanol etc.Show Answer
Answer Cross-linked or network polymer.Show Answer
Answer The given polymer is formed by’, 1, 4–addition of 2- methylbuta- 1,3-diene (isoprene) and stereochemistry is ‘cis’ throughout. Therefore, the given polymer is ‘cis’- polyisoprene i.e., natural rubber.Show Answer
Answer They change their shape on applying force and regain their original shape on removal of the applied force. Hence, rubbers are called elastomers.Show Answer
Answer Yes, these are made up of proteins which are polymers of amino acids.Show Answer
Answer Yes, nucleic acid, protein and starch can be considered as step growth polymers as during their polymerisation reaction, they lead to removal of water molecule or any neutral molecule also. Thus, these are the examples of condensation polymers or step growth polymerisation.Show Answer
Answer Reaction between melamine and formaldehyde can be shown as Melamine-formaldehyde polymer is formed by this monomer unit.Show Answer
Answer Cross links in rubber required for increasing the elasticity of rubber.Show Answer
Answer cis-polyisoprene is also known as natural rubber. Its elastic property is due to the existence of weak van der Waals’ interactions between their various polymer chains.Show Answer
Answer HDP (high density polymer) consists of linear molecule and has a high density due to close packing. It is a translucent polymer. While LDP (low density polymer) has highly branched structure and hence, does not pack well resulting in low density. It is a transparent material.Show Answer
Answer Role of benzoyl peroxide is to initiate the free radical polymerization reaction which can be easily understood by taking an example of polymerization of ethene to polyethene.Show Answer
Answer Strong intermolecular forces like hydrogen bonding and linear structure that lead to close packing of chains and hence, imparts crystalline character. e.g., nylonShow Answer
Answer Urea formaldehyde resin is used for laminated sheets. The monomer of this resin is urea $\left(\mathrm{NH} _{2} \mathrm{CoNH} _{2}\right)$ and formaldehyde $(\mathrm{HCHO})$Show Answer
Answer Polyamides have structural repeatation of amide linkages which is similar to peptide bond as present in polypeptide chains of proteins.Show Answer
Show Answer
Answer
During free radical polymerisation, monomers should be very pure because even very trace amounts of impurities may act as inhibitors which leads to the formation of polymers with shorter length.
Matching the Columns
38. Match the polymer of Column I with correct monomer of Column II.
Column I | Column II | ||
---|---|---|---|
A. | High density polyethene | 1. | Isoprene |
B. | Neoprene | 2. | Tetrafluoro ethene |
C. | Natural rubber | 3. | Chloroprene |
D. | Teflon | 4. | Acrylonitrile |
E. | Acrilan | 5. | Ethene |
Answer A. $\rightarrow$ (5) B. $\rightarrow$ (3) C. $\rightarrow(1)$ D. $\rightarrow(2)$ E. $\rightarrow(4)$ Column I represents various kind of polymer and Column II represents their monomer units. Correct matching can be done asShow Answer
Column I
Column II
A.
High density polymer
Ethene
B.
Neoprene
Chloroprene
C.
Natural rubber
Isoprene
D.
Teflon
Tetrafluoroethene
E.
Acrilan
Acrylonitrile
Column I | Column II | ||
---|---|---|---|
A. | Nylon-6 | 1. | Polyvinyl chloride |
B. | PVC | 2. | Polyacrylonitrile |
C. | Acrilan | 3. | Polycaprolactum |
D. | Natural rubber | 4. | Low density polythene |
E. | LDP | 5. | cis-polyisoprene |
Answer A. $\rightarrow(3)$ B. $\rightarrow(1)$ C. $\rightarrow(2)$ D. $\rightarrow(5)$ E. $\rightarrow(4)$ Column I represents various polymers and Column II represents their chemical names.Show Answer
Column I
Column II
A.
Nylon-6
Polycaprolactum
B.
PVC
Polyvinyl chloride
C.
Acrilan
Polyacrylonitrile
D.
Natural rubber
cis-polyisoprene
E.
LDP
Low density polythene
Column I | Column II | ||
---|---|---|---|
A. | Polyester of glycol and phthalic acid | 1. | Novolac |
B. | Copolymer of 1, 3-butadiene and styrene | 2. | Glyptal |
C. | Phenol and formaldehyde resin | 3. | Buna-S |
D. | Polyester of glycol and terephthalic acid | 4. | Buna-N |
E. | Copolymer of 1,3- butadiene and acrylonitrile | 5. | Dacron |
Answer A. $\rightarrow$ (2) B. $\rightarrow(3)$ C. $\rightarrow(1)$ D. $\rightarrow(5)$ E. $\rightarrow(4)$ Column I represents monomers of polymer and Column II represents their commercial name.Show Answer
Column I
Column II
A.
Polyester of glycol and phthalic acid
Glyptal
B.
Copolymer of 1, 3-butadiene and styrene
Buna-S
C.
Phenol and formaldehyde resin
Novolac
D.
Polyester of glycol and terephthalic acid
Dacron
E.
Copolymer of 1, 3-butadiene and acrylonitrile
Buna-N
Column I | Column II | ||
---|---|---|---|
A. | Bakelite | 1. | Unbreakable crockery |
B. | Low density polyethene | 2. | Non-stick cookwares |
C. | Melamine-formaldehyde resin | 3. | Packaging material for shock absorbance |
D. | Nylon-6 | 4. | Electrical switches |
E. | Polytetrafluoroethane | 5. | Squeeze bottles |
F. | Polystyrene | 6. | Tyre, cords |
Answer A. $\rightarrow(4)$ C. $\rightarrow(1)$ E. $\rightarrow(4)$Show Answer
Column I
Column II
A.
Bakelite
Electrical switches
B.
Low density polyethene
Squeeze bottles
C.
Melamine-formaldehyde resin
Unbreakable crockery
D.
Nylon-6
Tyre, cords
E.
Polytetrafluoroethane
Non-stick cookwares
F.
Polystyrene
Packaging material for shock absorbance
Column I | Column II | ||
---|---|---|---|
A. | Nylon-6,6 | 1. | Free radical polymerisation |
B. | PVC | 2. | Ziegler-Natta polymerisation or coordination polymerisation |
C. | HDP | 3. | Anionic polymerisation |
4. | Condensation polymerisation |
Answer A. $\rightarrow$ (4) B. $\rightarrow(1)$ C. $\rightarrow(2)$ Column I represents name of various polymer and Column II represents mechanism of polymerisation. Correct matching can be done asShow Answer
Column I
(Polymer)Column II
(Mechanism of polymerisation)
A.
Nylon- 6,6
Condensation polymerisation
B.
PVC
Free radical polymerisation
C.
HDP
Ziegler-Natta polymerisation or
coordination polymerisation
Column I | Column II | ||
---|---|---|---|
A. | Terylene | 1. | Glycosidic linkage |
B. | Nylon | 2. | Ester linkage |
C. | Cellulose | 3. | Phosphodiester linkage |
D. | Protein | 4. | Amide linkage |
E. | RNA |
Answer A. $\rightarrow(2)$ B. $\rightarrow(4)$ C. $\rightarrow(1)$ D. $\rightarrow(4)$ E. $\rightarrow$ (3) Column I represents name of polymer and Column II represents types of linkage. Hence, correct matching can be done asShow Answer
Column I
Column II
A.
Terylene
Ester linkage
B.
Nylon
Amide linkage
C.
Cellulose
Glycosidic linkage
D.
Protein
Amide linkage
E.
RNA
Phosphodiester linkage
Column I | Column II | ||
---|---|---|---|
A. | Natural rubber latex | 1. | Nylon |
B. | Wood laminates | 2. | Neoprene |
C. | Ropes and fibres | 3. | Dacron |
D. | Polyester fabric | 4. | Melamine formaldehyde resins |
E. | Synthetic rubber | 5. | Urea-formaldehyde resins |
F. | Unbreakable crockery | 6. | cis-polyisoprene |
Answer A. $\rightarrow(6)$ B. $\rightarrow(5)$ C. $\rightarrow(1)$ D. $\rightarrow$ (3) E. $\rightarrow$ (2) F. $\rightarrow(4)$ Column I represents various uses or precursurs of polymers and Column II represents name of related polymer. The correct matching can be done asShow Answer
Column I
Column II
A.
Natural rubber latex
cis-polyisoprene
B.
Wood laminates
Urea-formaldehyde resins
C.
Ropes and fibres
Nylon
D.
Polyester fabric
Dacron
E.
Synthetic rubber
Neoprene
F.
Unbreakable crockery
Melamine formaldehyde resins
Show Answer
Answer
A. $\rightarrow(4)$
B. $\rightarrow(1)$
C. $\rightarrow(2)$
D. $\rightarrow(4)$
E. $\rightarrow(3)$
Column I represents name of polymer and Column II represents their molecular formula. The correct matching can be done as
Assertion and Reason
In the following questions a statement of assertion (A) followed by a statement of reason ( $\mathrm{R}$ ) is given. Choose the correct answer out of the following choices.
(a) Assertion and Reason both are correct statement But reason does not explain Assertion.
(b) Assertion and Reason both are correct statements and Reason explains the Assertion.
(c) Both assertion and reason are wrong statements.
(d) Assertion is correct statement and Reason is wrong statement.
(e) Assertion is wrong statement and reason is correct statement.
46. Assertion (A) Rayon is a semisynthetic polymer and is taken as a better choice than cotton fabric.
Reason (R) Mechanical and aesthetic properties of cellulose can be improved by Acetylation.
Answer (b) Assertion and reason both are correct and reason explains the assertion. Rayon is a semisynthetic polymer and is taken as a better choice than cotton fabric because mechanical and aesthetic properties of cellulose can be improved by acetylationShow Answer
Reason (R) Polymerisation process induces toxic character in organic molecules.
Answer (d) Assertion is correct statement but reason is not correct statement. Most of synthetic polymers are not biodegradable because they are not easily broken by soil organisms and hazardous to the environment.Show Answer
Reason (R) Polymerisation of vinyl chloride is initiated by peroxides/persulphates.
Answer (a) Assertion and reason both are correct but reason does not explain assertion. Olefin monomers undergo addition polymerisation because it add on to other monomers of olefin through free radical mechanism due to the presence of peroxide initiator and double bond and produces high molecular mass polymers.Show Answer
Reason (R) Strong intermolecular forces (like hydrogen bonding within polyamides) lead to close packing of chains and increase the crystalline character, hence, provide high tensile strength to polymers.
Answer (b) Assertion and reason both are correct and reason explains assertion. Polyamides are best used as fibres because of high tensile strength. This is due to strong intermolecular forces (like hydrogen bonding within polyamides) lead to close packing of chains and increase the crystalline character, hence, provide high tensile strength to polymers.Show Answer
Reason ( $R$ ) Neoprene (a polymer of chloroprene) is a synthetic rubber.
Answer (e) Assertion is wrong and reason is correct statement. Correct assertion is, neoprene is a naturally occurring polymer of chloroprene prepared by polymerisation of 2-chloro butadiene.Show Answer
Reason (R) Network polymers have high molecular mass.
Answer (a) Assertion and reason both are correct and reason does not explain assertion. Network polymers are thermosetting because they can’t be reused after heating once. Because after heating it undergo extensive cross linking in moulds and again become infusible.Show Answer
Reason (R) Fluorine has highest electronegativity.
Show Answer
Answer
(a) Assertion and reason both are correct but reason does not explain assertion.
Polytetrafluoroethene (teflon) is used in making non-stick cookwares because it is chemically inert, thermally stable and resistant to attack by corrosive reagents.
Long Answer Type Questions
53. Synthetic polymers do not degrade in the environment for a long time. How can biodegradable synthetic polymers be made. Differentiate between biopolymers and biodegradable polymers and give examples of each type.
Answer Synthetic polymers are quite resistant to environmental degradation process and are responsible for accumulation of polymer solid waste material. New biodegradable synthetic polymers have been designed and developed. These polymers contain similar functional groups as present in biopolymers. e.g., aliphatic polyesters Biopolymer, are polymers of amino acid or carbohydrates which are linked to each other by peptide or glycosidic linkages as shown below Starch (polymer of glucose) Biopolymer can or can’t be biodegradable. e.g., protein, starch etc, are biodegradable but keratin are non-biodegradable. Biodegradable polymer are polymers which can be degradable always. e.g., DHBV nylon-2, Nylon-6Show Answer
Answer Rubber is a natural polymer which possess elastic properties. Natural polymer is a linear polymer of isoprene (2-methyl-1, 3-butadiene). In natural rubber cis-polyisoprene molecules consists of various chains held together by weak van der Waals’ interaction and has coiling structure. So, it can be stretched like a spring. Plastics are generally polymer of ethene known as polythene. Polythene is thermoplastic polymer which may be linear (HDP) or branched (LDP) these type of polymers. Possesses intermediate intermolecular forces of attraction. It has linear, structure that can be moulded but can’t be regained on its original shape after stretching.Show Answer
Answer Phenol and formaldehyde undergo condensation to give a polymer novolac $(A)$ which on heating with formaldehyde gives bakelite $(B)$ as a thermosetting polymer. Sequence of the reaction can be written as Structural difference in between these two is that novolac is a linear polymer while bakelite is a cross linked polymer.Show Answer
Answer Low density and high density polythenes are obtained under different conditions. These differ in their structural features. Low density polythenes are highly branched structures while high density polythene consists of closely packed linear molecules. Close packing increases the density.Show Answer
Show Answer
Answer
Polythene, polyvinyls and polystyrene soften on heating and harden on cooling. Such polymers are called thermoplastic polymers. These polymers are linear array of slightly branched long chain molecules.
These possess intermolecular forces whose strength lies between strength of intermolecular forces of elastomers and fibres while bakelite, urea formaldehyde resin are thermosetting polymers which on heating undergo extensive cross linking in moulds and again become infusible.