Classification of Polymer Questions in English

(C) Thermosetting polymers are cross-linked or heavily branched molecules that undergo extensive cross-linking in molds during hardening,becoming infusible and insoluble.
Urea-formaldehyde resin is a classic example of a thermosetting polymer formed by the condensation polymerization of urea and formaldehyde.
Polyvinyl chloride,polystyrene,and Nylon $6,6$ are thermoplastic polymers,which soften on heating and harden on cooling.

(A) copolymer is a polymer formed from two or more different types of monomeric units.
$Buna-S$ is a copolymer formed from $1,3-butadiene$ and $styrene$.
$Nylon$ $6,6$ is also a copolymer formed from $hexamethylenediamine$ and $adipic$ $acid$.
However,in the context of standard chemistry questions,$Buna-S$ is the most common example of a synthetic rubber copolymer.
Note: Both $A$ and $D$ are technically copolymers,but $Buna-S$ is the classic example of an addition copolymer.

(C) Cross-linked polymers are formed from bi-functional and tri-functional monomers and contain strong covalent bonds between various linear polymer chains.
$Melamine$ is a classic example of a cross-linked polymer,which is a thermosetting plastic formed by the condensation polymerization of melamine and formaldehyde.
$High \ density \ polyethylene$,$Low \ density \ polyethylene$,and $PVC$ are examples of linear or branched thermoplastic polymers.

(A) Thermosetting polymers are cross-linked or heavily branched molecules,which undergo extensive cross-linking in molds and again become infusible.
Common examples include Bakelite,urea-formaldehyde resin,and melamine-formaldehyde resin.
Therefore,urea-formaldehyde resin is a thermosetting polymer.

(D) Thermocol,also known as expanded polystyrene $(EPS)$,is a homopolymer. $A$ homopolymer is a polymer that is composed of only one type of monomer unit repeated throughout its structure. In the case of thermocol,the repeating unit is the styrene monomer. When polymerized,styrene forms a long chain known as polystyrene,which is used in a variety of applications,including packaging materials like thermocol.
Here is a brief description of each option to clarify why the others are not homopolymers:
Polycarbonate $(A)$: Polycarbonate is a copolymer commonly made from bisphenol $A$ and phosgene,thus it is not a homopolymer.
Buna-$N$ $(B)$: Buna-$N$,also known as nitrile rubber,is a copolymer made from butadiene and acrylonitrile.
Glyptal $(C)$: Glyptal is a copolymer derived from the reaction between glycerol and phthalic anhydride,classifying it as a copolymer.

(C) Addition polymerization involves the repeated addition of monomers possessing double or triple bonds without the loss of any small molecules.
$A$,$B$,and $D$ are examples of addition polymers (Polyethylene,Polyacrylonitrile,and Polyvinyl chloride respectively).
$C$ represents Nylon-$6$,which is formed by the ring-opening polymerization of caprolactam,a type of condensation polymerization where a small molecule is involved in the ring-opening process,or more generally,it is classified under condensation polymers due to the amide linkage formation.

(D) copolymer is a polymer formed from two or more different types of monomer units.
Buna-$S$ is a copolymer formed from $1,3$-butadiene and styrene.
Nylon $6$ is a homopolymer of caprolactam.
Nylon $6,6$ is a copolymer of hexamethylenediamine and adipic acid (Note: While Nylon $6,6$ is technically a copolymer,in many standard chemistry contexts,Buna-$S$ is the classic example of a synthetic rubber copolymer. However,both $B$ and $D$ are copolymers. Given the standard curriculum,Buna-$S$ is the most distinct example of an elastomer copolymer).

(A) Buna-$S$ is a synthetic elastomer,also known as styrene-butadiene rubber $(SBR)$. It has rubber-like properties and can stretch and return to its original shape,making it an elastomer.
Here is a quick breakdown of the other options:
- $(B)$ Nylon $6,6$: This is a nylon polymer,a type of polyamide used for fibers and engineering plastics,not an elastomer.
- $(C)$ Terylene: Also known as polyethylene terephthalate $(PET)$,it is a thermoplastic used in fibers and films,not an elastomer.
- $(D)$ Polythene: Also called polyethylene,it is a thermoplastic polymer used in packaging,containers,etc.,but not an elastomer.

(C) Thermoplastic polymers are linear or slightly branched long-chain molecules that soften on heating and harden on cooling. They do not possess extensive cross-linking by covalent bonds; such cross-linking is characteristic of thermosetting polymers.

(D) $Dacron$ and $Nylon \ 6$: Synthetic polymer.
$Wool$: Natural polymer.
$Cellulose \ nitrate$: Semisynthetic polymer.

(A) homopolymer is a polymer formed from only one type of monomer unit.
Polyacrylonitrile is formed by the polymerization of acrylonitrile $(CH_2=CH-CN)$ monomers only,making it a homopolymer.
Glyptal is a copolymer formed from ethylene glycol and phthalic acid.
Polycarbonate is a copolymer formed from bisphenol-$A$ and phosgene.
Buna-$S$ is a copolymer formed from $1,3$-butadiene and styrene.

(B) Elastomers are polymers in which the polymer chains are held together by the weakest intermolecular forces. These weak forces permit the polymer to be stretched. $A$ few crosslinks are introduced in between the chains,which help the polymer retract to its original position after the force is released. Examples include Buna-$S$,Buna-$N$,and natural rubber. Nylon $6,6$ is a fiber,Terylene is a fiber,and Polythene is a thermoplastic polymer.

(A) Linear polymers consist of long and straight chains. $High \ density \ polythene$ $(HDPE)$ is a linear polymer formed by addition polymerization of ethene under specific conditions (low pressure and use of Ziegler-Natta catalyst).
$Low \ density \ polythene$ $(LDPE)$ is a branched-chain polymer.
$Bakelite$ and $Melamine$ are cross-linked or network polymers.

(D) Terylene is a copolymer formed by the polymerization of two different monomers,ethylene glycol and terephthalic acid.
Natural rubber,polypropene,and $PVC$ (polyvinyl chloride) are homopolymers because they are formed from a single type of monomer unit.

(D) $PHBV$ is a copolymer of two bifunctional $\beta$-hydroxy carboxylic acids,namely,$3$-hydroxybutanoic acid and $3$-hydroxypentanoic acid.
$SBR$ (Styrene-Butadiene Rubber) is a copolymer of styrene and $1,3$-butadiene.
Both $SBR$ and $PHBV$ are examples of copolymers.

(A) Thermosetting polymers are cross-linked or heavily branched molecules that undergo extensive cross-linking during molding,which makes them hard and infusible.
$A$. Urea formaldehyde resin is a classic example of a thermosetting polymer.
$B$. Polythene is a thermoplastic polymer.
$C$. Polystyrene is a thermoplastic polymer.
$D$. Polyvinyls (like $PVC$) are thermoplastic polymers.
Therefore,the correct option is $A$.

(A) Elastomers are polymers that have weak intermolecular forces of attraction,which allow the polymer to be stretched.
$Neoprene$ is a synthetic rubber and is classified as an elastomer.
$Terylene$ is a polyester (fiber),$Polystyrene$ is a thermoplastic,and $Bakelite$ is a thermosetting polymer.

(B) Cuprammonium rayon is a semi-synthetic polymer.
It is prepared by dissolving cellulose (a natural polymer) in an ammoniacal solution of copper$(II)$ hydroxide,followed by spinning the solution into an acid bath.

(C) $i$. Linear polymer: $Polyvinylchloride$ $(PVC)$ consists of long,straight chains of monomers.
$ii$. Branched chain polymer: $Polypropylene$ contains branches along the main chain.
$iii$. Network or cross-linked polymers: $Vulcanised \text{ } rubber$ and $Melamine$ contain cross-links between polymer chains.

(B) Thermoplastic polymers are linear or branched chain molecules that can be repeatedly softened on heating and hardened on cooling.
Because of this property,they can be remoulded and recycled.
Therefore,the correct property is that they are either linear or branched chain polymers.

(C) Elastomers are polymers in which the polymer chains are held together by the weakest intermolecular forces. These weak forces permit the polymer to be stretched.
$Neoprene$ (polychloroprene) is a synthetic rubber and belongs to the class of elastomers.
$Polystyrene$ is a thermoplastic,$Nylon$ is a fiber,and $Bakelite$ is a thermosetting polymer.

(A) Thermosetting polymers are heavily cross-linked polymers.
When heated,they undergo extensive cross-linking in molds and become infusible and insoluble.
Therefore,they cannot be softened or remoulded by heating,which makes them non-recyclable.
Thus,the correct property is that they are cross-linked polymers.

(B) Thermoplastic polymers are linear or slightly branched long-chain molecules that can be repeatedly softened on heating and hardened on cooling.
$Polythene$ is a classic example of a thermoplastic polymer.
$Bakelite$ is a thermosetting polymer.
$Terylene$ is a polyester fiber (often considered a thermoplastic,but $Polythene$ is the most standard textbook example for this classification).
$Neoprene$ is a synthetic rubber (elastomer).

(C) Thermoplastic polymers are linear or slightly branched long-chain molecules capable of repeatedly softening on heating and hardening on cooling.
$Polystyrene$ is a well-known thermoplastic polymer.
$Bakelite$ is a thermosetting polymer.
$Nylon-6$ is a fiber (polyamide).
$Neoprene$ is an elastomer.
Therefore,the correct answer is $Polystyrene$.

(A) Nylon-$6$ is a linear polymer and does not show cross-linking. It is obtained by heating caprolactam with water at a high temperature. In contrast,Bakelite,Melamine,and Vulcanised rubber are cross-linked polymers. The structure of Nylon-$6$ is given by: $[CO-(CH_2)_5-NH]_n$.

(D) polymer that becomes soft on heating and hard on cooling belongs to the class of $Thermoplastic$ polymers.
When these polymers are heated,they become soft enough to be moulded into various shapes,such as $polyethene$ and $polystyrene$.

(C) Natural polymers are those polymers which are found in plants and animals.
Among the given options,$Nylon$,$Teflon$,and $Orlon$ are synthetic polymers.
$Linen$ is a natural polymer obtained from the flax plant,primarily composed of cellulose,which is a natural polymer of glucose molecules.

(A) Semi-synthetic polymers are derived from naturally occurring polymers by chemical modifications.
$Viscose-Rayon$,$Cupra-ammonium \text{ } silk$,and $Acetate \text{ } Rayon$ are examples of semi-synthetic polymers derived from cellulose.
$Terylene$ (also known as $Dacron$) is a synthetic polymer formed by the condensation polymerization of $terephthalic \text{ } acid$ and $ethylene \text{ } glycol$.

(C) Thermoplastic polymers are linear or branched chain polymers that soften on heating and harden on cooling.
They can be remoulded into different shapes repeatedly.
Therefore,the correct statement is that they are either linear or branched chain polymers.

(C) Rayon is a semi-synthetic polymer obtained from wood pulp,which is why it is classified as a regenerated fibre. It is also commonly known as artificial silk because its texture and appearance resemble natural silk.

(A) Natural rubber is a linear polymer of isoprene ($2$-methyl-$1,3$-butadiene).
Its chemical structure is $(CH_2=C(CH_3)-CH=CH_2)$.
It is a cis-$1,4$-polyisoprene.

(C) Polythene (Option $C$) is a thermoplastic polymer. Thermoplastics are materials that become pliable or moldable above a specific temperature and solidify upon cooling. They can be remelted and remolded multiple times without losing their chemical properties. Polythene,commonly known as polyethylene,is widely used in applications like packaging films,containers,and insulation for cables due to its flexibility,strength,and recyclability.
Urea formaldehyde resin (Option $A$) and Bakelite (Option $B$) are examples of thermosetting polymers,which harden permanently after being heated and cannot be remolded.
Buna-$N$ (Option $D$) is a synthetic rubber,not a thermoplastic.

(A) Polymers are classified into different types based on their intermolecular forces,such as elastomers,fibres,thermoplastic polymers,and thermosetting polymers.
- $Fibres$ are thread-forming solids which possess high tensile strength and high modulus.
- $Polyesters$ (such as polyethylene terephthalate or $PET$) are classic examples of fibres because they have strong intermolecular forces like hydrogen bonding or dipole-dipole interactions,which allow them to be drawn into long,thin threads for textile applications.
- $Vulcanized$ $rubber$ is an elastomer,while $Polythene$ and $Polyvinyls$ are thermoplastic polymers.

(B) The classification of polymers based on their structure is as follows:
$1$. High density polyethylene $(HDPE)$: Linear chain polymer.
$2$. Low density polyethylene $(LDPE)$: Branched chain polymer.
$3$. Bakelite: Cross-linked or network polymer.
$4$. Melamine: Cross-linked or network polymer.
Therefore,the correct answer is $B$.

(C) Polymers are classified based on intermolecular forces into elastomers,fibres,thermoplastics,and thermosetting polymers.
Fibres are thread-forming solids that possess high tensile strength and high modulus.
These characteristics are due to strong intermolecular forces like hydrogen bonding or dipole-dipole interactions.
Examples of fibres include polyamides (nylon-$6,6$) and polyesters (Terylene).
Vulcanized rubber,Buna-$S$,and Polystyrene are classified as elastomers or thermoplastics,which do not exhibit the strong intermolecular forces characteristic of fibres.

(D) Low density polythene $(LDPE)$ is a branched chain polymer formed by the free radical polymerization of ethene at high pressure and temperature. It contains long chains with random branches.

(A) homopolymer is a polymer formed from only one type of monomer unit.
$Teflon$ is a homopolymer of tetrafluoroethene $(CF_2=CF_2)$.
$Nylon$ $2-$nylon $6$,$PHBV$,and $Bakelite$ are copolymers because they are formed from two or more different types of monomer units.

(C) copolymer is a polymer formed from two or more different types of monomer units.
Buna-$S$ is a copolymer formed by the polymerization of $1,3-$butadiene and styrene.

(D) Melamine-formaldehyde resin is formed by the co-polymerisation of melamine and formaldehyde.
It is a classic example of a cross-linked polymer,where the polymer chains are connected by covalent bonds to form a three-dimensional network structure.

(C) Cross-linked polymers are formed from bi-functional and tri-functional monomers and contain strong covalent bonds between various linear polymer chains.
$PVC$,$Orlon$,and $Polypropylene$ are examples of linear or thermoplastic polymers.
$Vulcanised$ $rubber$ is a classic example of a cross-linked polymer,where sulfur bridges create cross-links between the polyisoprene chains,making the material harder and more durable.

(D) Terylene is a condensation polymer formed by the reaction between ethylene glycol and terephthalic acid. Since it involves the elimination of small molecules like water,it is a condensation polymer,which is a type of step-growth polymer. It is also a polyester and a copolymer because it is made from two different monomers. It is $NOT$ a chain-growth polymer,as chain-growth polymerization typically involves addition polymerization of unsaturated monomers.

(B) Polymers are classified based on intermolecular forces into elastomers,fibres,thermoplastics,and thermosetting polymers.
$1$. Elastomers (e.g.,Neoprene) have the weakest intermolecular forces,allowing the polymer chains to be stretched.
$2$. Thermoplastics (e.g.,Polythene,Polystyrene) have intermediate intermolecular forces.
$3$. Fibres (e.g.,Terylene) have the strongest intermolecular forces,such as hydrogen bonding or dipole-dipole interactions,which result in high tensile strength and crystalline nature.
Therefore,Terylene,being a fibre,has the strongest intermolecular forces among the given options.

(A) $Nylon-6,6$ is a polymer containing amide linkages,therefore,it is a polyamide.
It is formed by the condensation polymerization of hexamethylene diamine and adipic acid:
$n NH_2(CH_2)_6NH_2 + n HOOC(CH_2)_4COOH \xrightarrow{\text{Polymerization}} [NH-(CH_2)_6-NH-CO-(CH_2)_4-CO]_n + 2n H_2O$

(A) The correct matches are as follows:
$A$. Buna-$N$-Rubber is an Elastomer $(III)$.
$B$. Terylene is a Fibre $(I)$.
$C$. Polystyrene is a Thermoplastic polymer $(IV)$.
$D$. Urea-Formaldehyde resin is a Thermosetting polymer $(II)$.
Thus,the correct sequence is $A-III, B-I, C-IV, D-II$.

(D) Thermoplastic polymers are linear or slightly branched long-chain molecules that are capable of repeatedly softening on heating and hardening on cooling.
Examples include $Polythene$,$polystyrene$,and $polyvinyls$.

(A) Semi-synthetic polymers are derived from naturally occurring polymers by chemical modifications.
Cellulose nitrate,cellulose acetate,and vulcanised rubber are examples of semi-synthetic polymers.
$Cis-polyisoprene$ (natural rubber) is a natural polymer obtained from the latex of rubber trees.

(A) Condensation polymers are formed by the repeated condensation reaction between two different bi-functional or tri-functional monomeric units,usually with the elimination of small molecules like water,alcohol,etc.
$1$. Bakelite: Formed by the condensation of phenol and formaldehyde. It is a condensation polymer.
$2$. Teflon: Formed by the addition polymerization of tetrafluoroethylene. It is an addition polymer.
$3$. Nylon-$6$: Formed by the ring-opening polymerization of caprolactam,which involves the elimination of water during the synthesis of the monomer or the process itself. It is classified as a condensation polymer.
$4$. Dacron (Terylene): Formed by the condensation reaction between ethylene glycol and terephthalic acid. It is a condensation polymer.
$5$. Polyisoprene: Formed by the addition polymerization of isoprene. It is an addition polymer.
$6$. Melamine: Formed by the condensation polymerization of melamine and formaldehyde. It is a condensation polymer.
$7$. Neoprene: Formed by the addition polymerization of chloroprene. It is an addition polymer.
The condensation polymers are: Bakelite,Nylon-$6$,Dacron,and Melamine.
Total count = $4$.

(A) Fibre $(X)$ is a polymer that has strong intermolecular forces like hydrogen bonding or dipole-dipole interactions,which lead to close packing and crystalline nature. $Dacron$ (also known as $Terylene$) is a polyester fibre.
Elastomer $(Y)$ is a polymer in which polymer chains are held together by the weakest intermolecular forces,allowing the polymer to be stretched. $Neoprene$ (polychloroprene) is a synthetic rubber,which is an elastomer.
Therefore,$Dacron$ is a fibre and $Neoprene$ is an elastomer.

(A) copolymer is a polymer formed from two or more different types of monomer units.
$1$. Option $A$ represents Buna-$S$ (Styrene-butadiene rubber),which is formed by the copolymerization of $1,3$-butadiene and styrene.
$2$. Option $B$ represents Polytetrafluoroethylene (Teflon),which is a homopolymer of tetrafluoroethene.
$3$. Option $C$ represents Polychloroprene (Neoprene),which is a homopolymer of chloroprene.
$4$. Option $D$ represents Polyvinyl chloride $(PVC)$,which is a homopolymer of vinyl chloride.
Therefore,the copolymer is represented in option $A$.