Mix Examples-Polymer Questions in English

(D) Vulcanised rubber contains sulphur cross-links between polymer chains,which makes the rubber stiff and durable.
Phenol-formaldehyde resins (like Bakelite) are thermosetting polymers that possess a three-dimensional cross-linked structure formed by heating novolac with formaldehyde.
Nylon is a linear thermoplastic polymer without cross-links.
Therefore,both $(A)$ and $(C)$ contain cross-links.

(D) $1$. $Nylon-6$ is formed by the polymerization of caprolactam,so statement $A$ is correct.
$2$. Natural rubber is a polymer of isoprene $(2-methyl-1,3-butadiene)$,so statement $B$ is correct (Note: The original option $B$ mentioned butadiene,which is technically incorrect as natural rubber is polyisoprene,but statement $D$ is explicitly false as Terylene is a polyester,not a monomer of $Nylon-6$).
$3$. Phenol-formaldehyde resin is indeed known as Bakelite,so statement $C$ is correct.
$4$. $Nylon-6$ is a polyamide,while Terylene is a polyester. Thus,statement $D$ is incorrect.

(B) The polymerisation of ethene involves the breaking of one mole of $C=C$ bond and the formation of two moles of $C-C$ bonds per mole of ethylene monomer unit in the polymer chain.
$\Delta H = \text{Bond energy of reactants} - \text{Bond energy of products}$
$\Delta H = (1 \times \text{Bond energy of } C=C) - (2 \times \text{Bond energy of } C-C)$
$\Delta H = 590 - (2 \times 331)$
$\Delta H = 590 - 662 = -72 \ kJ \ mol^{-1}$.

(A) . Bakelite is a cross-linked polymer formed by the condensation of phenol and formaldehyde,making it a condensation polymer $(Q)$ and a copolymer $(S)$.
$B$. Nylon-$6$ is formed by the ring-opening polymerization of caprolactam,making it a homo polymer $(P)$.
$C$. Terylene is a condensation polymer $(Q)$,a copolymer $(S)$,and a polyester $(R)$.
$D$. $PHBV$ (poly-$\beta$-hydroxybutyrate-co-$\beta$-hydroxyvalerate) is a condensation polymer $(Q)$,a copolymer $(S)$,and a polyester $(R)$.
Thus,the correct matching is $A-(Q,S), B-(P), C-(Q,R,S), D-(Q,R,S)$.

(D) $PHBV$ and $Nylon-2-nylon-6$ are biodegradable polymers. This statement is correct.
$(b)$ Bakelite is a polymer of phenol and formaldehyde,not urea and formaldehyde. This statement is incorrect.
$(c)$ Novolac is a linear product of phenol and formaldehyde used in paints. This statement is correct.
$(d)$ Terylene and $Nylon-6,6$ are condensation polymers (fibers),not thermoplastic polymers. This statement is incorrect.
$(e)$ Teflon is an addition polymer of tetrafluoroethene. This statement is correct.
Therefore,the incorrect statements are $(b)$ and $(d)$.

(C) $1$. Glyptal is a polyester formed by the condensation of ethylene glycol and phthalic acid. The structure shown in $(i)$ is incorrect as it does not represent the repeating unit of Glyptal.
$2$. Bakelite is a cross-linked polymer formed by the condensation of phenol and formaldehyde. The structure shown in $(ii)$ correctly represents the cross-linked structure of Bakelite.
$3$. Nylon $6,6$ is a polyamide formed by the condensation of hexamethylenediamine and adipic acid. The structure shown in $(iii)$ correctly represents the repeating unit of Nylon $6,6$: $[-NH-(CH_2)_6-NH-CO-(CH_2)_4-CO-]_n$.
$4$. Therefore,both $(ii)$ and $(iii)$ are correct.

(D) Step $1$: Calculate the molar mass of $CaC_2$ $(40 + 2 \times 12 = 64 \ g/mol)$.
Step $2$: From the stoichiometry,$1 \ mol$ of $CaC_2$ produces $1 \ mol$ of $C_2H_2$,which produces $1 \ mol$ of $C_2H_4$.
Step $3$: $n \ mol$ of $C_2H_4$ produces $1 \ mol$ of polyethylene unit $(-CH_2-CH_2-)$ of molar mass $28 \ g/mol$.
Step $4$: $64 \ kg$ of $CaC_2$ is $1000 \ mol$.
Step $5$: Therefore,$1000 \ mol$ of $C_2H_4$ will produce $1000 \ mol$ of ethylene units in the polymer.
Step $6$: Mass of polyethylene = $1000 \ mol \times 28 \ g/mol = 28000 \ g = 28 \ kg$.

(D) Natural rubber is a polymer of isoprene ($2-$methyl-$1, 3-$butadiene). Thus,the assertion is false.
Natural rubber is formed by the polymerization of isoprene,which typically proceeds via free radical or coordination polymerization,not anionic addition polymerization. Thus,the reason is also false.

(A-II, B-III, C-I, D-V, E-IV) The correct matches are:
$A$ (Polyester of glycol and phthalic acid) matches with $ii$ (Glyptal).
$B$ (Copolymer of $1,3$-butadiene and styrene) matches with $iii$ (Buna-$S$).
$C$ (Phenol and formaldehyde resin) matches with $i$ (Novolac).
$D$ (Polyester of glycol and terephthalic acid) matches with $v$ (Dacron).
$E$ (Copolymer of $1,3$-butadiene and acrylonitrile) matches with $iv$ (Buna-$N$).
Therefore,the correct sequence is: $A-ii, B-iii, C-i, D-v, E-iv$.

(A-VI, B-V, C-I, D-III, E-II, F-IV) The correct matches are as follows:
$A$ (Natural rubber latex) $\rightarrow$ $vi$ (cis-polyisoprene)
$B$ (Wood laminates) $\rightarrow$ $v$ (Urea-formaldehyde resins)
$C$ (Ropes and fibres) $\rightarrow$ $i$ (Nylon)
$D$ (Polyester fabric) $\rightarrow$ $iii$ (Dacron)
$E$ (Synthetic rubber) $\rightarrow$ $ii$ (Neoprene)
$F$ (Unbreakable crockery) $\rightarrow$ $iv$ (Melamine formaldehyde resins)
Therefore,the correct sequence is: $A-vi, B-v, C-i, D-iii, E-ii, F-iv$.

(B) Alcoholic potassium hydroxide is used for $\beta$-elimination reactions.
$(b)$ $Pd / BaSO_4$ is known as Lindlar's catalyst.
$(c)$ $BHC$ (Benzene hexachloride) is obtained by the addition reaction of chlorine to benzene.
$(d)$ Polyacetylene is a conducting polymer used as electrodes in batteries.
Therefore,the correct match is $a-iii, b-iv, c-ii, d-i$.

(D) . $2$-Chloro-$1,3$-butadiene is the monomer of Neoprene,which is a synthetic rubber $(A-II)$.
$B$. Nylon-$2$-nylon-$6$ is a copolymer of glycine and amino caproic acid,which is a biodegradable polymer $(B-I)$.
$C$. Polyacrylonitrile is formed by the polymerization of acrylonitrile,which is an addition polymer $(C-IV)$.
$D$. Dacron (also known as Terylene) is a polyester formed by the condensation of ethylene glycol and terephthalic acid $(D-III)$.
Therefore,the correct matching is $A-II, B-I, C-IV, D-III$.

(A) - $A$. Weak intermolecular forces of attraction: $2-$chloro$-1,3-$butadiene (chloroprene) is the monomer of Neoprene,which is an elastomer (rubber) characterized by weak intermolecular forces.
- $B$. Hydrogen bonding: Hexamethylenediamine reacting with adipic acid forms Nylon-$6,6$,which exhibits strong hydrogen bonding due to the presence of amide groups.
- $C$. Heavily branched polymer: Phenol and formaldehyde react to form Bakelite,which is a heavily branched (cross-linked) thermosetting polymer.
- $D$. High density polymer: $AlEt_3 + TiCl_4$ is the Ziegler-Natta catalyst used to prepare high-density polyethylene $(HDPE)$.
Therefore,the correct matching is $A-III, B-I, C-IV, D-II$.

(D) $1$. Cellulose is a natural polymer $(p)$ and contains glycoside linkages $(s)$.
$2$. Nylon-$6,6$ is a synthetic polymer $(q)$ and contains amide linkages $(r)$.
$3$. Protein is a natural polymer $(p)$ and contains amide linkages $(r)$.
$4$. Sucrose is a disaccharide (not a polymer) and contains a glycoside linkage $(s)$.
Therefore,the correct matches are: $A$ $\rightarrow p, s; B$ $\rightarrow q, r; C$ $\rightarrow p, r; D$ $\rightarrow s$.

(A) Based on the provided reaction scheme:
$P$ is $CH_{3}CH(OH)CH_{2}CH=CHCH_{2}CH(OH)CH_{2}CH_{3}$.
Ozonolysis of $P$ with $H_{2}O_{2}$ yields $Q$ ($CH_{3}CH(OH)CH_{2}COOH$,$\beta$-hydroxybutyric acid) and $R$ ($CH_{3}CH_{2}CH(OH)CH_{2}COOH$,$\beta$-hydroxyvaleric acid).
Oxidation of $Q$ with $PCC$ gives $\beta$-ketobutyric acid,which on heating undergoes decarboxylation to give $S$ ($CH_{3}COCH_{3}$,acetone).
Oxidation of $R$ with $PCC$ gives $\beta$-ketovaleric acid,which on heating undergoes decarboxylation to give $T$ ($CH_{3}CH_{2}COCH_{3}$,butan$-2-$one).
Both $S$ and $T$ contain one oxygen atom each,so the sum of oxygen atoms is $1+1=2$.
For copolymerization,$500$ moles of $Q$ ($C_{4}H_{8}O_{3}$,$MW=104$) and $500$ moles of $R$ ($C_{5}H_{10}O_{3}$,$MW=118$) react to form $1$ mole of copolymer $U$ with the loss of $999$ moles of water ($H_{2}O$,$MW=18$).
$MW_{U} = (500 \times 104) + (500 \times 118) - (999 \times 18) = 52000 + 59000 - 17982 = 111000 - 17982 = 93018$.

(C) . The monomer of Teflon is $C_2F_4$ $(II)$.
$B$. $RLi$ $(V)$ is used in the initiation of anionic polymerisation.
$C$. $SnCl_2$ $(I)$ is used for cationic polymerisation.
$D$. Bakelite $(III)$ is a thermosetting polymer.
Therefore,the correct matching is $A-II, B-V, C-I, D-III$. Hence,option $(C)$ is correct.

(A) . The polymer $(CH_2-C(Cl)=CH-CH_2)_n$ is Neoprene,which is an elastomer.
$B$. Nylon-$6,6$ is a synthetic polymer classified as a fibre.
$C$. High-density polyethylene $(HDP)$ is synthesized using a Ziegler-Natta catalyst.
$D$. Melamine-formaldehyde is a thermosetting polymer with a cross-linked network structure.
Therefore,the correct matching is $A-II, B-III, C-IV, D-I$.

(A) For a spontaneous reaction,the Gibbs free energy change must be negative,i.e.,$\Delta G < 0$.
In a polymerization reaction,many monomer units combine to form a single polymer chain $(n A \rightarrow A_n)$.
This process leads to a decrease in the number of particles and an increase in order,resulting in a decrease in entropy,i.e.,$\Delta S < 0$.
Using the Gibbs-Helmholtz equation: $\Delta G = \Delta H - T \Delta S$.
Since $\Delta G < 0$ and $\Delta S < 0$,the term $-T \Delta S$ becomes positive.
For $\Delta G$ to remain negative,the enthalpy change $\Delta H$ must be negative and its magnitude must be greater than the magnitude of $T \Delta S$,i.e.,$\Delta H < 0$.