Exams › JEE Main › Chemistry › Polymers
82 questions with worked solutions.
Q1. Which process gives rise to a straight-chain polymer?
Answer: Hydrolysis of (CH3)2SiCl2 followed by condensation polymerisation
Hydrolysis of the difunctional (CH3)2SiCl2 followed by condensation polymerisation gives a linear (straight-chain) silicone. Silicones polymerise by condensation, not addition, so the stored option's mechanism is wrong.
Q2. Which of the following polymers is not formed with cross-linking between chains?
Answer: Polythene
Melmac (melamine-formaldehyde), Bakelite (phenol-formaldehyde) and vulcanised rubber are all cross-linked (network) polymers. Polythene is a linear/branched chain-growth polymer with no cross-links, so it is the odd one out.
Q3. Which compound or pair of compounds is employed in the production of nylon 6?
Answer: Cyclohexanone
Nylon-6 is made by ring-opening polymerization of caprolactam, which is prepared from cyclohexanone (via its oxime and Beckmann rearrangement). Among the choices, cyclohexanone is the relevant starting material. Styrene gives polystyrene, and the adipic acid + hexamethylenediamine pair gives Nylon-6,6.
Q4. Ebonite is best described as which of the following?
Answer: rubber that has been heavily vulcanized
Ebonite is a type of hard rubber that has undergone extensive vulcanization, which enhances its durability and rigidity, making it distinct from other forms of rubber.
Q5. Which monomer gives rise to the polymer with repeating unit [—CH2—C(CH3)2—]n?
Answer: 2-Methylpropene
The polymer with the repeating unit [—CH2—C(CH3)2—]n is derived from 2-methylpropene, which contains a branched structure that leads to the formation of this specific polymer upon polymerization.
Q6. Polymerisation of caprolactam produces which of the following polymers?
Answer: Nylon-6
Caprolactam is a cyclic amide (lactam); its ring-opening polymerisation produces the polyamide Nylon-6 (-NH-(CH2)5-CO-)n. Terylene is a polyester of ethylene glycol and terephthalic acid.
Q7. Which polymer is employed in bullet-proof glass?
Answer: Lexan
Bullet-proof and impact-resistant transparent panels are made from Lexan, the trade name for polycarbonate, prized for extreme toughness. PMMA (acrylic/Plexiglas) is far more brittle, Nomex and Kevlar are aramid fibres used in protective fabrics, not glazing.
Answer: Neoprene; [—CH2—C(Cl)=CH—CH2—CH2—]n
Neoprene (polychloroprene) has the repeat unit [-CH2-CCl=CH-CH2-]n (four carbons). The option writes an extra CH2 as [-CH2-C(Cl)=CH-CH2-CH2-]n, which is incorrect. Terylene, Nylon 66 and Teflon are written correctly.
Q9. Which of the following pairs can be used to produce a biodegradable polymer?
Answer: H2N—CH2—COOH and H2N—(CH2)5—COOH
The correct option consists of amino acids, which can polymerize to form peptides or proteins, leading to biodegradable polymers. These natural polymers can break down in the environment, unlike many synthetic alternatives.
Q10. Which catalyst is employed in the manufacture of high-density polythene?
Answer: Ziegler–Natta catalyst
The Ziegler–Natta catalyst is specifically designed for the polymerization of alkenes, making it ideal for producing high-density polythene due to its ability to control the polymer structure and molecular weight.
Q11. Identify the monomer used to prepare neoprene from the following compounds.
Answer: CH2=C(Cl)—CH=CH2
The correct option is a chlorinated diene, which can undergo polymerization to form neoprene, a synthetic rubber. The presence of the chlorine atom in the monomer facilitates the polymerization process, leading to the formation of a stable polymer structure.
Q12. Buna-N rubber is formed by copolymerizing which pair of monomers?
Answer: Acrylonitrile and 1,3-butadiene
Buna-N rubber is a type of synthetic rubber created through the copolymerization of acrylonitrile and 1,3-butadiene, which imparts oil resistance and durability to the final product.
Q13. Which polymer is known for having strong intermolecular attractions, such as hydrogen bonding?
Answer: Nylon 6,6
Nylon 6,6 is a polyamide that features strong hydrogen bonding between its amide groups, leading to enhanced intermolecular attractions and resulting in its high strength and durability.
Q14. Which of the following represents a Ziegler–Natta catalyst system?
Answer: Al2(C2H5)6 + TiCl4
The Ziegler–Natta catalyst system is characterized by the combination of a transition metal compound, such as titanium tetrachloride (TiCl4), with an organoaluminum compound, like diethylaluminum chloride (Al2(C2H5)6), which facilitates the polymerization of alkenes.
Q15. Nylon 6,6 is a polyamide formed by the condensation reaction between which pair of monomers?
Answer: HOOC(CH2)4COOH + H2N(CH2)6NH2
Nylon 6,6 is synthesized from hexamethylenediamine and adipic acid, which corresponds to the monomers in option B. The condensation reaction between these two compounds forms the polyamide structure characteristic of Nylon 6,6.
Q16. Polymerization of which monomer produces neoprene?
Answer: CH2=C(Cl)–CH=CH2
The correct option, CH2=C(Cl)–CH=CH2, contains a vinyl group that can undergo polymerization to form neoprene, a synthetic rubber. This process involves the addition of the monomer's double bonds to create long polymer chains.
Q17. Which starting materials are employed to produce nylon-6,6?
Answer: Adipic acid and hexamethylenediamine
Nylon-6,6 is synthesized through a condensation reaction between adipic acid and hexamethylenediamine, which provides the necessary amine and carboxylic acid functional groups to form the polyamide structure.
Q18. Plexiglas, also known as PMMA, is formed by polymerization of which monomer?
Answer: methyl methacrylate
Methyl methacrylate is the monomer that undergoes polymerization to form PMMA, commonly known as Plexiglas, making it the correct choice.
Q19. Orlon is formed by polymerization of which monomer?
Answer: acrylonitrile
Orlon is a synthetic fiber made from the polymerization of acrylonitrile, which is a key monomer that forms polyacrylonitrile, the basis of Orlon's structure.
Answer: Dynel
Dynel is a synthetic fiber made from a copolymer of vinyl chloride and acrylonitrile, which gives it properties similar to human hair, making it suitable for wig production.
Q21. Melamine tableware is formed as a condensation polymer from which pair of monomers?
Answer: Formaldehyde and melamine
Melamine tableware is created through a chemical reaction between melamine and formaldehyde, resulting in a durable and heat-resistant condensation polymer.
Answer: I-E, II-A, III-C, IV-B
Hexamethylenediamine is a key monomer in the production of Nylon, while Phenol is used to create Bakelite. Phthalic acid is a monomer for Glyptal, and Terephthalic acid is essential for the synthesis of Dacron, making the correct matches I-E, II-A, III-C, and IV-B.
Answer: natural rubber
Natural rubber consists of long, flexible polymer chains with relatively weak van der Waals forces between them, leading to lower intermolecular attraction compared to the more rigid and structured polymers like nylon, cellulose, and poly(vinyl chloride).
Q24. Which of the following repeating-unit structures corresponds to neoprene polymer?
Answer: –CH2–C(Cl)=CH–CH2–
The correct option represents the repeating unit of neoprene, which is a synthetic rubber made from the polymerization of chloroprene. The structure includes a vinyl group and a chlorine atom, characteristic of neoprene's chemical composition.
Answer: Polytetrafluoroethylene
Polytetrafluoroethylene (PTFE) is widely recognized for its non-stick properties, making it an ideal choice for coating cookware, as it reduces friction and prevents food from sticking.
Answer: (A)-(iii), (B)-(iv), (C)-(i), (D)-(ii)
Caprolactam -> Nylon 6 (iii); 2-chloro-1,3-butadiene (chloroprene) -> Neoprene (iv); isoprene -> Natural rubber (i); acrylonitrile -> Buna-N (ii). So (A)-(iii), (B)-(iv), (C)-(i), (D)-(ii).
Answer: (A), (B) and (D) only
Silicones are known for their hydrophobic properties, making them water-repellent (A), they are also biocompatible, which allows them to be safely used in medical applications (B), and they exhibit resistance to oxidation, making them suitable for use as greases (D). However, they typically have high thermal stability and good dielectric strength, contradicting statement (C), which is why it is not included.
Q28. Which of the following is a polyamide?
Answer: Nylon-66
Nylon-66 is a type of polyamide, which is a polymer characterized by the presence of amide linkages in its molecular structure, making it suitable for various applications such as textiles and engineering materials.
Q29. Which one is classified as a condensation polymer ?
Answer: Dacron
Dacron is a type of polyester formed through the condensation reaction of diols and dicarboxylic acids, resulting in the release of water molecules during the polymerization process.
Q30. Which of the following statements is not true ? [JEE-Main On line-2018]
Answer: Chain growth polymerisation involves homopoly-merisation only
The statement that is NOT true is 'Chain growth polymerisation involves homopolymerisation only.' Chain-growth polymerisation can be either homopolymerisation or copolymerisation (e.g. SBR). Nylon-6 is step-growth and step-growth needs bifunctional monomers, so those statements are true.
Answer: (a), (b) and (d) only
Options (a), (b), and (d) are correct because silicones are indeed hydrophobic polymers, they exhibit biocompatibility, and they are resistant to oxidation, making them suitable for use as greases. However, option (c) is incorrect as silicones typically have low thermal stability and high dielectric strength.
Q32. Which of the following is a condensation polymer?
Answer: Nylon 6,6
Nylon 6,6 is made by condensation polymerization of hexamethylenediamine and adipic acid (eliminating water). Neoprene, Buna-S and Teflon are addition polymers.
Q33. Which of the following is a thermosetting polymer?
Answer: Bakelite
Bakelite is a thermosetting polymer because it undergoes a chemical change when heated, forming a rigid structure that cannot be remolded. This characteristic distinguishes it from thermoplastics, which can be reshaped upon heating.
Q34. Which of the following compounds is a constituent of the polymer [–HN–C(=O)–NH–CH2–]n ?
Answer: Formaldehyde
The repeating unit [-HN-C(=O)-NH-CH2-]n is urea-formaldehyde resin, formed from urea and formaldehyde. Among the choices, formaldehyde is the constituent monomer.
Answer: (3) 3-hydroxybutanoic acid and 3-hydroxypentanoic acid
PHBV is a copolymer of beta-hydroxybutyrate (3-hydroxybutanoic acid) and beta-hydroxyvalerate (3-hydroxypentanoic acid).
Q36. Which polymer has 'chiral' monomer(s) ?
Answer: PHBV
PHBV is made from 3-hydroxybutyrate and 3-hydroxyvalerate, both of which contain chiral centers in their molecular structure, leading to the formation of a polymer with chiral monomers.
Q37. Monomer units of Dacron polymer are:
Answer: ethylene glycol and terephthalic acid
Dacron is a type of polyester made from the polymerization of ethylene glycol and terephthalic acid, which combine to form long chains that give the material its strength and durability.
Q38. Bakelite is a cross-linked polymer of formaldehyde and:
Answer: Novolac
Bakelite is a cross-linked phenol-formaldehyde resin; the linear/branched phenol-formaldehyde intermediate that cross-links into Bakelite is Novolac.
Q39. Orlon fibres are made up of:
Answer: Polyacrylonitrile
Orlon fibres are synthetic fibers primarily composed of polyacrylonitrile, which is a type of acrylic polymer known for its lightweight and insulating properties.
Answer: (1)
The synthesis of Buna-S, a type of synthetic rubber, requires nascent oxygen to facilitate the polymerization process, making this statement accurate.
Q41. Which among the following is not a polyester ? (1) Novolac (2) PHBV (3) Dacron (4) Glyptal
Answer: Novolac
Novolac is a phenol-formaldehyde resin (a phenolic polymer), so it is NOT a polyester. PHBV, Dacron (terylene), and Glyptal are all polyesters.
Answer: o-Hydroxymethylphenol
Novolac is a phenol-formaldehyde resin formed under acidic conditions; its monomeric intermediate is o-hydroxymethylphenol, which condenses to give the linear polymer. 3-Hydroxybutanoic acid is the monomer of PHB, not Novolac.
Answer: Poly-β-hydroxybutyrate-co-β-hydroxy valerate
Poly-β-hydroxybutyrate-co-β-hydroxy valerate is a type of polyester because it is formed through the polymerization of hydroxy acids, which contain ester linkages characteristic of polyester materials.
Q44. Vulcanization of rubber is carried out by heating a mixture of
Answer: isoprene and sulphur
Vulcanization heats natural rubber (cis-polyisoprene) with sulphur, which forms cross-links between chains; the mixture is isoprene (rubber) and sulphur.
Answer: A-II, B-III, C-I, D-IV
A (phenol-formaldehyde) -> Novolac (II); B (butadiene-styrene copolymer) -> Buna-S (III); C (glycol + phthalic acid) -> Glyptal (I); D (glycol + terephthalic acid) -> Dacron (IV). So A-II, B-III, C-I, D-IV.
Answer: (3)
Buna-N is specifically produced through the copolymerization of 1,3-butadiene and acrylonitrile, which gives it unique properties suitable for various applications, particularly in the production of synthetic rubber.
Answer: A-III, B-II, C-IV, D-I
The correct option matches the structures of the polymers with their respective categories: A is an elastomer due to its flexible structure, B is a fiber because of its strong, linear arrangement, C is a thermoplastic polymer as it can be reshaped upon heating, and D represents a thermosetting polymer due to its cross-linked structure that hardens permanently.
Q48. Which one of the following is NOT a copolymer?
Answer: Neoprene
Neoprene is a homopolymer made from chloroprene, whereas the other options are copolymers formed from two different monomers. This distinction makes Neoprene the only option that does not fit the definition of a copolymer.
Q49. Which of the following is NOT a natural polymer?
Answer: Rayon
Proteins, starch, and natural rubber are all naturally occurring polymers. Rayon is regenerated cellulose (a man-made, semi-synthetic fibre), so it is NOT a natural polymer.
Answer: Buna-N
Buna-N is a type of elastomer that exhibits elastic properties, allowing it to be stretched and return to its original shape once the force is removed, making it suitable for applications requiring flexibility and resilience.