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CBSE Questions for Class 12 Engineering Chemistry Polymers Quiz 5 - MCQExams.com
CBSE
Class 12 Engineering Chemistry
Polymers
Quiz 5
Neoprene, a synthetic rubber contains which of the following element besides C and H?
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$$N$$
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$$O$$
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$$Cl$$
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$$F$$
Explanation
Neoprene (also polychloroprene) is a family of synthetic rubbers that are produced by polymerization of chloroprene. It has chlorine atom besides hydrogen and carbon element.
Hence, option $$C$$ is correct.
Teflon is obtained by the polymerization of:
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Monofluoroethene
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Difluoroethene
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Trifluoroethene
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Tetrafluoroethene
Explanation
Teflon is an addition polymer of tetrafluoroethylene (Tetrafluoroethene).
Hence, option $$D$$ is correct.
In the natural rubber ‘Caoutchouc’, the isoprene units are joined by:
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Head-to-head
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Tail-to-tail
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Head-to-tail
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All of these
Explanation
Natural rubber Caoutchouc means natural rubber that has not been vulcanized.
It is generally conceded that natural rubber consist of 1,4 structural units in head-to-tail sequence and this arrangement is confirmed by X-ray diffraction of highly stretched rubber.
Hence, option $$A$$ is correct.
Molecular mass of a polymer is:
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Small
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Very small
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Negligible
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Large
Explanation
The molecular mass of a polymer chain can be obtained by multiplying the mass of each repeating unit by the degree of polymerization and then adding the mass of end groups.
A polymer is a substance or material consisting of very large molecules, or macromolecules, composed of many repeating subunits. Hence, the molecular mass of a polymer is large.
Hence, option $$D$$ is correct.
Which of the following is synthetic rubber?
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Buna-S
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Neoprene
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Both (a) and (b)
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None of these
Explanation
Synthetic rubber is capable of getting stretched to twice its length. However, it returns to its original shape and size as soon as the external stretching force is released.
The different types of synthetic rubber include neoprene, Buna rubbers, and butyl rubbers.
Hence, option $$C$$ is correct that both Buna-S and Neoprene are synthetic rubbers.
Bakelites are:
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Rubber
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Rayon
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Resins
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Plasticisers
Explanation
Bakelite is a thermosetting phenol formaldehyde resin, formed from a condensation reaction of phenol with formaldehyde.
Hence, option $$C$$ is correct.
Which of the following statements are incorrect about phenol- formaldehyde resin?
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Novolac or resin is a linear polymer and is used in the manufacture of adhesive.
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Novolac on heating with formaldehyde undergoes cross linking to form an infusible solid mass called bakelite
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Novolac is prepared when (P/F) (phenol/formaldehyde) ratio is greater than 1, whereas bakelite is prepared when (P/F) ratio is less than 1
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Novolac on heating with formaldehyde undergoes cross linking to form an infusible solid called melamine
Explanation
Novolac is used in the manufacturing of adhesive. Novolacs are phenol-formaldehyde resins with a $$\dfrac{P}{F}$$ ratio of greater than one.
Bakelite or polyoxybenzylmethylenglycolanhydride is an early plastic. It is a thermosetting phenol-formaldehyde resin, formed from an elimination reaction of phenol with formaldehyde having $$\dfrac{P}{F}$$ ratio is less than 1.
Novolac on heating with formaldehyde undergoes cross-linking to form an infusible solid mass called bakelite.
Options A, B, and C are correct statements while option D is incorrect.
State whether the statement is true or false. Rewrite the false statement correctly.
Polyvinyl chloride is a polymer of chloroethane.
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True
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False
Explanation
Polyvinyl chloride is a polymer of chloroethene (vinyl choloride).
A high molecular weight molecule built from a large number of small molecules is called a ____.
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monomer
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isomer
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polymer
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tautomer
Explanation
A polymer is a large molecule composed of many repeated subunits, known as monomers. Because of their broad range of properties, both synthetic and natural polymers play an essential and ubiquitous role in everyday life. Polymers range from familiar synthetic plastics such as polystyrene to natural biopolymers such as DNA and proteins, that are fundamental to biological structure and function.
Polymers, both natural and synthetic, are created via polymerisation of many monomers. Their large molecular mass relative to small molecular compounds produces unique physical properties, including toughness, viscoelasticity and a tendency to form glasses and semicrystalline structures rather than crystals.
Hence, the correct option is $$C$$
Natural rubber is a:
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trans isomer
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cis isomer
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racemic mixture
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equal amount of cis and trans
Chloroprene is used in making
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synthetic rubber
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plastic
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petrol
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All of the above
Explanation
Chloroprene is the monomer of neoprene, a synthetic rubber formed by the free radical polymerisation of choloroprene.
$$nCH_2-CCl-CH=CH_2 \xrightarrow {Polymerisation} -[CH_2-CCl=CH-CH_2]-$$
Which of the following has the largest molecular mass?
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Monomer
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Dimer
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Polymer
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Oligomer
Explanation
Molecular mass is a number equal to the sum of the atomic masses of the atoms in a molecule.
A monomer is a molecule that forms the basic unit for polymers.
A dimer is an oligomer consisting of two monomers joined by bonds that can be either strong or weak, covalent, or intermolecular.
A polymer is a chemical compound with molecules bonded together in long, repeating chains.
An oligomer is a molecular complex of chemicals that consists of a few repeating units.
The polymer has the highest number of repeating units and hence, the maximum number of atoms, so it has the largest molecular mass.
Hence, option $$C$$ is corret.
Which is not a polymer
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Ice
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Starch
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Protein
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Cellulose
Explanation
Starch, protein, cellulose are natural polymer.
Ice is the solid state of water $$(H_2O)$$.
Hence, option $$A$$ is the answer.
Styrene at room temperature is:
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Solid
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Liquid
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Gas
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Colloidal solution
Explanation
At room temperature and pressure, styrene is a clear, colorless liquid that is an important monomer of synthetic rubber.
Hence, $$B$$ is correct.
Which one is a polymer compound?
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$$SO_2$$
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$$CO_2$$
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$$CH_4$$
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$$PVC$$
Explanation
$$SO_2$$, $$CO_2$$ and $$CH_4$$ are chemical compounds and found in gas state at room temperature.
PVC (polyvinyl chloride) is the addition polymer of vinyl chloride.
Hence, option $$D$$ is the answer.
Natural rubber contains several thousand units of $$X$$, linked together in the polymer chain. $$X$$ is:
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Neoprene
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Isoprene
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Chloroprene
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Styrene
Explanation
Natural rubber is an addition polymer that is obtained as a milky white fluid known as latex from a tropical rubber tree. Natural rubber is from the monomer isoprene (2-methyl-1,3-butadiene). So, X is isoprene.
Hence, option B is correct.
The monomer of natural polymer rubber is:
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Neoprene
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Isoprene
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Chloroprene
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Butadiene
Explanation
Natural rubber is an addition polymer that is obtained as a milky white fluid known as latex from a tropical rubber tree. Natural rubber is from the monomer isoprene (2-methyl-1,3-butadiene).
Hence, option $$B$$ is correct.
Characteristic property of Teflon is:
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2000 poise viscosity
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High surface tension
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Non-inflammable and resistant to heat
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Highly reactive
Explanation
Teflon is nonreactive, partly because of the strength of carbon-fluorine bonds.
Teflon is non-inflammable and resistant to heat so it is used in coating, particularly in non-sticking frying pans.
Hence, option $$C$$ is correct.
Bakelite is:
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Chain-growth polymer
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Step-growth polymer
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Both (a) and (b)
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Elastomer
Which of the following polymers can be used for lubrication and as an insulator?
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SBR
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PAN
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PTFE
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PVC
Explanation
PTFF (Play tetrafluoroethene) or Teflon is used for lubrication and as on insulator.
Teflon is manufactured by heating tetrafluokoethane with a free radical or per sulfate catalyst at high pressures. It has high flexural strength, even in low temperature, high electrical resistance and low coefficient of friction.
$$\underset{Tetrafluoro \ ethane}{nCF_2 = CF_2} \xrightarrow[high P]{catalyst} \underset{Tejlon}{-\!\!\![ \ CF_2 - CF_2-\!\!\!]_n}$$
So, correct option is (C)
Which of the following is a common example of fibres?
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Bakelite
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Buna-S
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Nylon-6,6
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Nylon-6
Explanation
Nylon-66 is the common example of fibre. Which is a polyamide. The linear polymer chains are held together by H-bonds between NH group of one chain.
Which of the following is a copolymer?
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Polytetrafluoroethylene
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Polyvinyl chloride
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Polyethylene
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Nylon-6,6
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Natural rubber
Explanation
A polymer derived from more than one species of monomer is a co-polymer e.g. Nylon - 6,6.
All others are formed by following single monomers:
Polytetrafluoroethylene - tetrafluoroethylene,
Polyvinyl chloride - vinyl chloride,
Polyethylene - ethylene and
Natural rubber or polyisoprene - isoprene (2-methyl-1,3-butadiene).
$$ \sim\!\! [\!\! \sim NH(CH_2)_6 NHCO(CH_2)_4 CO\sim\!]_n\!\!\!\!\! \!\sim$$ is:
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Addition polymer
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Copolymer
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Homopolymer
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Thermosetting polymer
Explanation
$$ \sim\!\! [\!\! \sim NH(CH_2)_6 NHCO(CH_2)_4 CO\sim\!]_n\!\!\!\!\! \!\sim$$ is
formed by the condensation of adipic acid. and hexamethylene diamine. It is a copolymer (a polymer made from more than one type of monomer molecules is referred to as copolymer).
The basic unit of neoprene is:
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Chloroprene
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Isoprene
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Styrene
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Butadiene
Explanation
The basic unit of neoprene is chloroprene, which forms neoprene by the process of polymerisation as shown in the above reaction.
A copolymer is:
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Styrene butadiene rubber
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Polythene
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Terylene
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Nylon
Explanation
A copolymer is a polymer formed when two (or more) different types of monomers are linked in the same polymer chain, as opposed to a homopolymer where only one monomer is used. And Styrene butadiene rubber is made up of two monomers, styrene and buta-1,3-diene.
Which of the following is not a condensation polymer?
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Nylon-6,6
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PTFE
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Dacron
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Glyptal
Explanation
PTFE is not a condensation polymer.
The material used for making non stick utensils kitchen is :
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PVC
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Polyether
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Teflon
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Rayon
The radical of phosphate among the following radicals is?
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$$PO_4^{2-}$$
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$$PO_4^{3-}$$
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$$PO_2^{4}$$
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$$PO_2^{2-}-$$
Natural rubber is a polymer of which substance?
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Neoprene
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Isoprene
0%
$$1,3$$-Butadiene
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Buna-N
Explanation
Natural rubber is a polymer of isoprene
For improving the tensile strength and quality of natural rubber, it is heated with sulphur. What is the name of this process?
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Polymerization
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Saponification
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Vulcanization
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Equalization
Vulcanization makes rubber
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more elastic
0%
soluble in inorganic solvent
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crystalline
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more stiff
Explanation
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.
Which of the following is not a true polymer?
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Ethene
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Styrene
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Isoprene
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Butadiene
Explanation
Ethene is $$\mathrm{C_2H_4}$$, Styrene is
$$\mathrm{Ph-CH=CH_2}$$, Isoprene is
$$\mathrm{CH_2-CH-C(CH_3)=CH_2}$$ and Butadiene is
$$\mathrm{CH_2=CH-CH=CH_2}$$
So, all of them are not polymers rather they are monomers.
Hence, Options "A", "B", "C" & "D" are correct answers.
Which of the following is condensation polymer?
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Dacron
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Teflon
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PVC
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Polythene
Explanation
Teflon, PVC and Polyethene are addition polymers but Dacron is a condensation polymer.
Hence, Option "A" is the correct answer.
On the basis of the method of polymerization, polymers are classified as:
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Only addition polymers
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Only condensation polymers
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both addition and condensation polymers
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Copolymers
Explanation
On the basis of the method of polymerization, polymers are classified as
both addition and condensation polymers.
Hence, Option "C" is the correct answer.
Teflon is a polymer of:
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Tetrafluoroethylene
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Tetraiodoethylene
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Tetrachloroethylene
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Tetrabromoethylene
Explanation
Teflon is a polymer of tetrafluoroethylene $$\mathrm{(C_2F_4)}$$.
Hence, Option "A" is the correct answer.
Select the correct statement(s) about the given polymer :
(i) Monomer is $$CH_{2}=CH-CH=CH_{2} $$ and $$ CH_{2}=CH-CN$$.
(ii) It is a copolymer.
(iii) It is an addition polymer.
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(i) and (ii) only
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(iii) only
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(ii) only
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(i), (ii) and (iii)
Explanation
The diagram shows the two monomeric units adding together to form the polymer. It is a copolymer and also an addition polymer.
$$X-(CH_2)_4-X \xrightarrow [{HOOC-(CH_2)_4-COOH}] {Y}\quad \text{Condensation Polymer}$$
The correct functional group $$X$$ and the reagent/reaction conditions $$Y$$ in the following scheme are:
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$$X=COOCH_{3},\ Y=H_{2}/Ni/heat$$
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$$X=CONH_{2},\ Y=H_{2}/Ni/heat$$
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$$X=CONH_{2},\ Y=Br_{2}/NaOH$$
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$$X=CN,\ Y=H_{2}/Ni/heat$$
Which set is correctly matched?
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Dacron or Terylene : Condensation polymer
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PVC : Biodegradable polymer
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Nylon - $$6,\: 6$$ : Addition polymer
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Buna-S rubber : Natural polymer
Explanation
A. Dacron or terylene is a polyester, which is formed by the condensation polymerization of ethylene glycol and terephthalic acid, along with the elimination of water molecules.
B. PVC is a non-biodegradable polymer.
C. Nylon 6,6 is made of two monomers each containing 6 carbon atoms, hexamethylenediamine, and adipic acid. It is a condensation polymer.
D. Buna-S- rubber is a synthetic polymer.
So the correct option is A.
The monomer of the polymer is:
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$$CH_{3}CH = CH.CH_{3}$$
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$$CH_{3}CH = CH_{2}$$
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$$(CH_{3})_{2} C = C (CH_{3})_{2}$$
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$$CH_2=C-CH_3$$
$$|$$
$$CH_3$$
Natural wool is scarce and expensive. Identify the synthetic fibre which can be substituted in its place for making winter wear.
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Polyester
0%
Acrylic
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Terylene
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Terycot
Explanation
Acrylic fibers are synthetic fibers made from a polymer (polyacrylonitrile) and is used to make artificial wool.
Correct option is 'B'
In the above shown sequence, the final product $$F$$ is :
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bakelite
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nylon - $$6$$
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polyester
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natural rubber
Explanation
$$Caprolactum$$ is prepared from $$phenol$$ via $$cyclohexanone$$ upon hydrogenation, oximation and Beckmann rearrangement.
This, on polymerization, gives Nylon - $$6$$.
Option B is correct.
Which is/are the correct statement(s) regarding the polymer kevlar?
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It is a polyamide.
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It is a copolymer.
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It has elastic property.
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It is an addition polymer.
Explanation
Kevlar is a nylon polymer and is obtained by condensation polymerization of terephthalic acid with $$1, 4$$-diamino benzene. It is a fibre used for making bullet proof
vests.
Buna-N synthetic rubber is a copolymer of:
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$$\mathrm{H}_{2}\mathrm{C}=\mathrm{C}\mathrm{H}-\mathrm{CH}=CH_2$$ and $$\mathrm{H}_{2}\mathrm{C}=\mathrm{C}\mathrm{H}-CH=\mathrm{C}\mathrm{H}_{2}$$
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$$\mathrm{H}_{2}\mathrm{C}=\mathrm{C}\mathrm{H}-CH=\mathrm{C}\mathrm{H}_{2}$$ and $$\mathrm{H}_{5}\mathrm{C}_{6}-CH=\mathrm{C}\mathrm{H}_{2}$$
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$$\mathrm{H}_{2}\mathrm{C}=\mathrm{C}\mathrm{H}-CN$$ and $$\mathrm{H}_{2}\mathrm{C}=\mathrm{C}\mathrm{H}-CH=\mathrm{C}\mathrm{H}_{2}$$
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$$\mathrm{H}_{2}\mathrm{C}=\mathrm{C}\mathrm{H}-CN$$ and $$\mathrm{H}_{2}\mathrm{C}=\mathrm{C}\mathrm{H}-\mathrm{C(CH_3)}=CH_2$$
Explanation
Correct Answer:
Option C
Explanation:
$$Buna-N$$ is a synthetic rubber copolymer made up of $$1,3-Butadiene$$
($$H_2C=CH$$ – $$CH=CH_2$$)
and acrylonitrile (
$$H_2C =CH $$– $$CN$$)
.
The synthesis is as follows:
Which of the following statements are correct about phenol-formaldehyde resin?
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Novolac or resin is a linear polymer and is used in the manufacture of adhesive.
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Bakelite is a cross-linked polymer and is used in making switches and plugs.
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Novolac is prepared when (P/F) (phenol/formaldehyde) ratio is greater than $$1$$, whereas bakelite is prepared when (P/F) ratio is less than $$1$$.
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Novolac is prepared when P/F $$< 1$$ and bakelite is prepared when P/F $$>1$$.
Explanation
Novolac is used in the manufacturing of adhesive. Novolacs are phenol-formaldehyde resins with a $$\dfrac{P}{F}$$ ratio of greater than one.
Bakelite or polyoxybenzylmethylenglycolanhydride is an early plastic. It is a thermosetting phenol-formaldehyde resin, formed from an elimination reaction of phenol with formaldehyde having $$\dfrac{P}{F}$$ ratio is less than 1. Bakelite is used for its electrical nonconductivity and heat-resistant properties in electrical insulators, radio and telephone casings.
Hence, options A, B, and C are correct.
Which of the following is copolymer?
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Styrene butadiene rubber
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Polythene
0%
Nylon
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None of the above
Explanation
Copolymers or heteropolymers are polymers formed by two or more different types of monomeric units. Styrene rubber or SBR (Styrene butadiene rubber) is prepared by the copolymerization of buta-$$1,3$$-diene ($$70\%$$) and styrene ($$30\%$$).
Polyethene and nylon are formed by only one type of monomeric unit. (ethene and caprolactam)
Option A is correct.
A polymeric sample in which $$30\%$$ molecules have a molecular mass $$20,000$$, $$40\%$$ have $$30,000$$ and the rest $$30\%$$ have $$60,000$$. The $$( \bar{M}_{n})$$ and
$$( \bar{M}_{w})$$
of this sample are, respectively:
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$$36,000,\: 43,333$$
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$$43,000,\: 36,000$$
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$$72,000,\: 86,000$$
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$$86,000, \:72,000$$
Explanation
Number average molecular weight
$$( \bar{M}_{n}) = \dfrac {\Sigma N_iM_i}{\Sigma N_i} = \dfrac {30(20000)+40(30000)+30(60000)}{30+40+30}=36000$$
Weight average molecular weight
$$( \bar{M}_{w}) = \dfrac {\Sigma N_iM_i^2}{\Sigma N_iM_i}=
\dfrac {30(20000)^2+40(30000)^2+30(60000)^2}{30(20000)+40(30000)+30(60000)}=43333$$
Hence, the $$( \bar{M}_{n})$$ and $$( \bar{M}_{w})$$ of this sample are, respectively $$36,000$$ and $$43,333$$
Statement 1: Bakelite is hard and has high melting point.
Statement 2: Intermolecular forces of attraction in it are H-bonding.
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Statement 1 is true; statement 2 is true; statement 2 is the correct explanation of statement 1
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Statement 1 is true; statement 2 is true; statement 2 is not the correct explanation of statement 1
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Statement 1 is true; statement 2 is false
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Statement 1 is false; statement 2 is true
Explanation
Assertion is true. Bakelite is a thermosetting polymer and has a high strength. It has heat-resistant properties in electrical insulators, radio and telephone casings and such diverse products as kitchenware, jewellery, pipe stems, children's toys, and firearms.Hence, have a very high melting point.
Reason is false: A thermoset is a polymer that is irreversibly cured, usually through covalent crosslinking (during or after polymerization). These undergo permanent changes. eg. Bakelite
Hence, answer is C
Silk clothes are prepared from silkworms at which of the following stage of its cycle?
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0%
0%
0%
Explanation
At the pupa stage, the silkworm spins a protective cocoon which serves as protection for the pupa. If the silkworms are allowed to mature and break through the cocoon the silk would be rendered useless for commercial purposes. So the encased insect is plunged into boiling water to kill inhabitant and the cocoon unwound onto a spindle to be made into thread.
Option C is correct.
The monomer unit for the given compound is:
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$$2$$-methylpropene
0%
styrene
0%
propylene
0%
ethene
Explanation
The monomer is 2-methylpropene. It polymerises by addition polymerisation.
Polymer used to make gasket of pressure cooker is:
Report Question
0%
polythene
0%
nylon
0%
teflon
0%
thiokol
Explanation
Polymer used to make gasket of pressure cooker is teflon. Teflon is formed by free radical vinyl polymerisation of the monomer tetrafluoroethylene.
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