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NCERT Exemplar Class 12 Chemistry Solutions Chapter 15 Polymers

NCERT Exemplar Class 12 Chemistry Solutions Chapter 15 Polymers

Edited By Sumit Saini | Updated on Sep 17, 2022 11:19 AM IST | #CBSE Class 12th

NCERT exemplar Class 12 Chemistry solutions chapter 15 is an important chapter which holds great importance in an exam point of view. It answers How did the manufacturing industries like clothing, toys, packaging, automobile, electrical, medicine, capsules flourish? What made our daily lives convenient and much more colourful? Who played a significant role in all these industries? NCERT exemplar Class 12 Chemistry chapter 15 solutions answers these questions with a single word- Polymer. Also, these NCERT exemplar Class 12 Chemistry solutions chapter 15 pdf download can help in accessing answers offline.

This Story also Contains
  1. NCERT Exemplar Class 12 Chemistry Solutions Chapter 1: MCQ (Type 1)
  2. NCERT Exemplar Class 12 Chemistry Solutions Chapter 1: MCQ (Type 2)
  3. NCERT Exemplar Class 12 Chemistry Solutions Chapter 1: Short Answer Type
  4. NCERT Exemplar Class 12 Chemistry Solutions Chapter 1: Matching Type
  5. NCERT Exemplar Class 12 Chemistry Solutions Chapter 1: Assertion and Reason Type
  6. Question:46
  7. NCERT Exemplar Class 12 Chemistry Solutions Chapter 1: Long Answer Type
  8. Major Topics and Subtopics in NCERT Exemplar Class 12 Chemistry Chapter 15 Solutions
  9. Class 12 Chemistry NCERT Exemplar Solutions Chapter 15 - Learning Outcomes
  10. NCERT Exemplar Class 12 Chemistry Solutions
  11. Important Topics in NCERT Exemplar Class 12 Chemistry Solutions Chapter 15

NCERT exemplar solutions for Class 12 Chemistry chapter 15 defines the word 'polymer' by two Greek words: poly meaning- many and mer meaning- part. A polymer is a giant molecule with a high molecular mass, made by linking together repetitive structural units on a massive scale, called monomers, forming polymers through polymerization.

Also, check - NCERT Solutions for Class 12, Other Subjects

The Class 12 Chemistry NCERT exemplar solutions chapter 15 provided here would help you clear your confusion between several polymers and help you get a clear understanding of this chapter to perform well in the 12 boards and competitive exams.

All of which are detailed in the NCERT exemplar solutions for Class 12 Chemistry chapter 15 which by utilising the NCERT exemplar Class 12 Chemistry solutions chapter 15 pdf download function. Students can make learning even more convenient as they will get access to quality study material effectively constructed by experts for the best learning experience.

NCERT Exemplar Class 12 Chemistry Solutions Chapter 1: MCQ (Type 1)

Question:1

Which of the following polymers of glucose is stored by animals?
(i) Cellulose
(ii) Amylose
(iii) Amylopectin
(iv) Glycogen

Answer:

The answer is the option (iv). Amongst the given options, glycogen is a polymer of glucose that is found in liver, brain and muscles of animals.

Question:2

Which of the following is not a semisynthetic polymer?
(i) cis-polyisoprene
(ii) Cellulose nitrate
(iii) Cellulose acetate
(iv) Vulcanised rubber

Answer:

The answer is the option (i). Of all the given options, Cis-polyisoprene is not a semisynthetic polymer. m-polyisoprene is a natural polymer while the others are semisynthetic polymers.

Question:3

The commercial name of polyacrylonitrile is ______________.
(i) Dacron
(ii) Orlon (Acrilan)
(iii) PVC
(iv) Bakelite

Answer:

The answer is the option (ii). The commercial name of polyacrylonitrile is Orion (acrilan). It is used as a substitute for wool in making commercial fibres.

Question:4

Which of the following polymer is biodegradable?


Answer:

The answer is the option (iii). PHBV is biodegradable in nature. It is formed by the copolymerisation of 3-hydroxybutanoic acid and 3-hydroxypentanoic acid.


Question:5

In which of the following polymers ethylene glycol is one of the monomer units?


Answer:

The answer is the option (i). The polymer given below is obtained on condensation polymerisation of ethylene glycol and phthalic acid. The water molecule gets eliminated in the process.

Question:6

Which of the following statements is not true about low-density polythene?
(i) Tough
(ii) Hard
(iii) Poor conductor of electricity
(iv) Highly branched structure

Answer:

The answer is the option (iii). We can obtain low-density polythene by polymerisation of ethane under high pressure. It tough but flexible (not too hard) in nature and has a highly branched structure.

Question:7


is a polymer having monomer units ____________.

Answer:

The answer is the option (i).

Question:8

Which of the following polymer can be formed by using the following monomer unit?

(i) Nylon 6, 6
(ii) Nylon 2–nylon 6
(iii) Melamine polymer
(iv) Nylon-6

Answer:

The answer is the option (iv). Nylon -6 is the polymer formed by heating caprolactam with water at a high temperature.


NCERT Exemplar Class 12 Chemistry Solutions Chapter 1: MCQ (Type 2)

Question:9

Which of the following polymers, need at least one diene monomer for their preparation?
(i) Dacron
(ii) Buna-S
(iii) Neoprene
(iv) Novolac

Answer:

The answer is the option (ii, iii) Buna-S and neoprene need at least one diene monomer in their preparation. Buna-S is prepared by copolymerisation of 1, 3-butadiene and styrene in the presence of peroxide catalyst.

Neoprene is formed by the free radical polymerisation of chloroprene.

Question:10

Which of the following are characteristics of thermosetting polymers?
(i) Heavily branched cross-linked polymers.
(ii) Linear slightly branched long-chain molecules.
(iii) Become infusible on moulding so cannot be reused.
(iv) Soften on heating and harden on cooling, can be reused.

Answer:

The answer is the option (i, iii) Thermosetting polymers or thermoset are heavily branched and cross-linked molecules. They cannot be reused as they become infusible on the moulding.

Question:11

Which of the following polymers are thermoplastic?
(i) Teflon
(ii) Natural rubber
(iii) Neoprene
(iv) Polystyrene

Answer:

The answer is the option (i, iv) Thermoplastic polymers can be repeatedly softened on heating and hardened on cooling. Thus, they can be remoulded again and again. Teflon and polystyrene are common examples of thermoplastics.

Question:12

Which of the following polymers are used as fibre?
(i) Polytetrafluoroethane
(ii) Polychloroprene
(iii) Nylon
(iv) Terylene

Answer:

The answer is the option (iii, iv) Fibres have high tensile strength and modulus due to strong intermolecular forces like H-bonding. This leads to close packing in chain resulting in crystalline nature. Polyamides (Nylon) and Polyesters (terylene) are used as fibres.

Question:13

Which of the following are addition polymers?
(i) Nylon
(ii) Melamine formaldehyde resin
(iii) Orlon
(iv) Polystyrene

Answer:

The answer is the option (iii, iv) Orion and polystyrene are examples of addition polymers formed by repeated addition of monomer molecules. Orion is made by polymerisation of \text {CH }_{2}=\text { CH - CN (acrylonitrile)} and polystyrene by \text {C}_{6}\text {H}_{5}-\text {CH=CH}_{2}\; \text {(styrene)}

Question:14

Which of the following polymers are condensation polymers?
(i) Bakelite
(ii) Teflon
(iii) Butyl rubber
(iv) Melamine formaldehyde resin

Answer:

The answer is the option (i, iv) Phenol when heated with formaldehyde gives an infusible solid mass known as bakelite. On condensation polymerisation of melamine and formaldehyde, melamine formaldehyde resin is obtained.

Question:15

Which of the following monomers form biodegradable polymers?
(i) 3-hydroxybutanoic acid + 3-hydroxypentanoic acid
(ii) Glycine + aminocaproic acid
(iii) Ethylene glycol + phthalic acid
(iv) Caprolactam

Answer:

The answer is the option (i, ii) The polymers which are easily decomposed are known as biodegradable polymer. PHBV is biodegradable in nature. It is formed by the copolymerisation of 3-hydroxybutanoic acid and 3-hydroxypentanoic acid. Glycine + amino caproic acid on copolymerisation give Nylon-2-nylon 6 which is also biodegradable.

Question:16

Which of the following is an example of a synthetic rubber?
(i) Polychloroprene
(ii) Polyacrylonitrile
(iii) Buna-N
(iv) cis-polyisoprene

Answer:

The answer is the option (i, iii)
Polychloroprene is a polymer of chloroprene and it is synthetic rubber.

Question:17

Which of the following polymers can have strong intermolecular forces?
(i) Nylon
(ii) Polystyrene
(iii) Rubber
(iv) Polyesters

Answer:

The answer is the option (i, iv). Polyamides (Nylon) and Polyesters (terylene) have high tensile strength and modulus due to strong intermolecular forces like H-bonding. This leads to close packing in the chain resulting in crystalline nature. That is why they are used as thread forming fibres.

Question:18

Which of the following polymers have vinylic monomer units?
(i) Acrilan
(ii) Polystyrene
(iii) Nylon
(iv) Teflon

Answer:

The answer is the option (i, ii, iv) Amongst the given options, acrilan, polystyrene and Teflon has vinylic
Monomer units.

Question:19

Vulcanisation makes rubber ______________.
(i) more elastic
(ii) soluble in inorganic solvent
(iii) crystalline
(iv) more stiff

Answer:

The answer is the option (i, iv). Vulcanisation is a chemical process wherein rubber is heated with Sulphur to form cross-links between rubber molecules. The process is carried to improve the physical properties like elasticity of natural rubber. It makes the rubber stiffer.

NCERT Exemplar Class 12 Chemistry Solutions Chapter 1: Short Answer Type

Question:20

A natural linear polymer of \text {2-methyl-1, 3-butadiene} becomes hard on treatment with sulphur between 373 to 415 K and \text {-S-S-} bonds are formed between chains. Write the structure of the product of this treatment?

Answer:

The structures of the Vulcanised rubber molecules are as given below.

Question:21

Identify the type of polymer.
\text {-A-A-A-A-A-A-}

Answer:

Polymerisation of single monomeric species (one type of monomer unit) gives homopolymers. In this case the unit is A.

Question:22

Identify the type of polymer.
\text {-A-B-B-A-A-A-B-A-}

Answer:

Polymers wherein repeating structural unit has 2 types of monomer units (let’s say A and B) are known as copolymers.

Question:23

Out of chain growth polymerisation and step-growth polymerisation, in which type willyou place the following.


Answer:

It is a type of chain growth polymerisation because only addition occurs in this.

Question:24

Identify the type of polymer given in the following figure.


Answer:

The polymer given in the diagram is a cross linked polymer because a 3- D network structure (giant molecule) is formed from various polymer chains.

Question:25

Identify the polymer given below :


Answer:

The polymer given is cis-polyisoprene (natural rubber) and has a coiled structure. It shows elastic properties as well.

Question:26

Why are rubbers called elastomers?

Answer:

Rubber is a natural polymer with elastic properties, i.e. it stretches and relaxes with the application or removal of external force. That is why these are called elastomers.

Question:27

Can the enzyme be called a polymer?

Answer:

Since enzymes are biocatalysts that are basically proteins, they can be called polymers.

Question:28

Can nucleic acids, proteins and starch be considered as step growth polymers?

Answer:

Step growth polymers are formed by condensation polymerisation reaction resulting in the loss of simple molecule like water, alcohol that in turn, results in the formation of high molecular mass polymers. Nucleic acids, proteins and starch are formed in the same way. Hence, they can be considered as step-growth polymers.

Question:29

How is the following resin intermediate prepared and which polymer is formed by this monomer unit?

Answer:

The given intermediate is formed by the condensation polymerisation of melamine and formaldehyde. Its polymerisation gives melamine formaldehyde.

Question:30

To have practical applications, why are cross-links required in rubber?

Answer:

Cross-links are formed in the process of vulcanisation which is done to improve the physical properties of natural rubber. By cross-linking, rubber gets hard and tough due to increased tensile strength. The vulcanised rubber has higher elasticity, increased stiffness and low water absorption tendency.

Question:31

Why does cis-polyisoprene possess elastic property?

Answer:

The cis-polyisoprene molecule has a coiled structure. In it, several chains are held together by weak van der Waals interactions. This is why they possess elastic property.

Question:32

What is the structural difference between \text {HDP} and \text {LDP}? How does the structure account for different behaviour and nature, hence the use of a polymer?

Answer:

\text {LDP} or Low-density polythene has a highly branched molecular structure. It has low density (0.92 g/cm 3) and low melting point, as the molecules do not pack well due to branching. It is transparent and chemically inert with moderate toughness.
\text {HDP} or High-density polythene has linear chains, and thus the molecules are closely packed in space. Therefore, it has a higher density and melting point. In comparison to \text {LDP}, it is harder, tougher and has greater tensile strength.

Question:33

What is the role of benzoyl peroxide also polymerisation of alkenes? Explain its mode of action with the help of an example.

Answer:

The role of Benzoyl peroxide in free radical addition polymerisation of alkenes is to generate free radicals and act as an initiator of the reaction by providing chain initiation.

The free radical is added to the double bond of an alkene molecule forming the polymer.

The new free radical is added to a double bond of monomer to form a larger free radical, which when added to other alkene molecules forms the polymer.

Lastly chain termination step-

Question:34

Which factor imparts crystalline nature to a polymer like nylon?

Answer:

Polymers like nylon have strong intermolecular forces like hydrogen bonding that lead to close packing of polymer chains. This, along with the linear structure, gives a crystalline nature to the polymer.

Question:35

Name the polymers used in laminated sheets and give the name of monomeric units involved in its formation.

Answer:

The polymer is a urea-formaldehyde resin and the monomeric units are urea and formaldehyde.

Question:36

Which type of biomolecules has some structural similarity with synthetic polyamides? What is this similarity?

Answer:

The biomolecules having some structural similarity with synthetic polyamides are protein. The similarity is that the polyamides and proteins both contain amide linkage.

Question:37

Why should the monomers used in addition polymerisation through free radical pathway be very pure?

Answer:

The monomers used in addition polymerisation through free radical should be very pure because even a tiny amount of impurities may act as initiators leading to the formation of polymers with small chain lengths.

NCERT Exemplar Class 12 Chemistry Solutions Chapter 1: Matching Type

Question:38

Match the polymer of column I with a correct monomer of column II.

Column I
Column II
(i) High density polythene
(a) Isoprene
(ii) Neoprene
(b) Tetrafluoroethene
(iii) Natural rubber
(c) Chloroprene
(iv) Teflon
(d) Acrylonitrile
(v) Acrilan
(e) Ethene
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Answer:

(i \rightarrow e), (ii \rightarrow c), (iii \rightarrowa), (iv \rightarrow b), (v \rightarrowd)

Question:39

Match the polymers given in Column I with their chemical names given in Column II.

Column I
Column II
(i) Nylon 6
(a) Polyvinyl chloride
(ii) PVC
(b) Polyacrylonitrile
(iii) Acrilan
(c) Polycaprolactum
(iv) Natural rubber
(d) Low density Polythene
(v) LDP
(e) cis-polyisoprene

Answer:

(i \rightarrow c), (ii \rightarrow a), (iii \rightarrow b), (iv \rightarrow e), (v \rightarrow d)

Question:40

Match the polymers given in Column I with their commercial names given in Column II.

Column I
Column II
(i) The polyester of glycol and phthalic acid
(a) Novolac
(ii) The copolymer of 1, 3-butadiene and styrene
(b) Glyptal
(iii) Phenol and formaldehyde resin
(c) Buna-S
(iv) The polyester of glycol and terephthalic acid
(d) Buna -N
(v) The copolymer of 1, 3-butadiene and acrylonitrile
(e) Dacron

Answer:

(i \rightarrow b), (ii \rightarrow c), (iii \rightarrow a), (iv \rightarrow e), (v \rightarrow d)

Question:41

Match the polymers given in Column I with their main applications given in Column II.

Column I
Column II
i) Bakelite
(a) Unbreakable crockery
ii) Low-density polythene
(b) Non-stick cookwares
iii) Melamine-formaldehyde resin
(c) Packaging material for shock absorbance
iv) Nylon 6
(d) Electrical switches
v) Polytetrafluoroethane
(e) Squeeze bottles
vi) Polystyrene
(f) Tyre, cords

Answer:

(i \rightarrow d), (ii \rightarrow e), (iii \rightarrow a), (iv \rightarrow f), (v \rightarrow b), (vi \rightarrow c)

Question:42

Match the polymers given in Column I with the preferred mode of polymerisation followed by their monomers.

Column I
Column II
(i) Nylon -6,6
(a) Free radical polymerisation
(ii) PVC
(b) Ziegler-Natta polymerisation or Co-ordination polymerisation
(iii) HDP
(c) Anionic Polymerisation

(d) Condensation polymerisation

Answer:

(i \rightarrow d), (ii \rightarrow a), (iii \rightarrow b)

Question:43

Match the polymers given in Column I with the type of linkage present in they have given in Column II.

Column I
Column II
(i) Terylene
(a) Glycosidic linkage
(ii) Nylon
(b) Ester linkage
(iii) Cellulose
(c) Phosphodiester linkage
(iv) Protein
(d) Amide linkage
(v) RNA

Answer:

(i \rightarrow b), (ii \rightarrow d), (iii \rightarrow a), (iv \rightarrow d), (v \rightarrow c)

Question:44

Match materials are given in Column I with the polymers given in Column II.

Column I
Column II
(i) Natural rubber latex
(a) Nylon
(ii) Wood laminates
(b) Neoprene
(iii) Ropes and fibres
(c) Dacron
(iv) Polyester fabric
(d) Melamine formaldehyde resins
(v) Synthetic rubber
(e) Urea-formaldehyde resins
(vi) Unbreakable crockery
(f) cis-polyisoprene

Answer:

(i \rightarrow f), (ii \rightarrow e), (iii \rightarrow a), (iv \rightarrow c), (v \rightarrow b), (vi \rightarrow d)

Question:45

Match the polymers given in Column I with their repeating units given in Column II

Column I
Column II
(i) Acrilan
(a)
(ii) Polystyrene
(b)
(iii) Neoprene
(c)
(iv) Novolac
(d)
(v) Buna-N
(e)

(f)

Answer:

(i \rightarrow d), (ii \rightarrow a), (iii \rightarrow b), (iv \rightarrow e),(v \rightarrow c)

NCERT Exemplar Class 12 Chemistry Solutions Chapter 1: Assertion and Reason Type

Question:46

In the following question a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
Assertion: Rayon is a semi-synthetic polymer and is taken as a better choice than cotton fabric.
Reason: Mechanical and aesthetic properties of cellulose can be improved by acetylation.
(i) Assertion and reason both are correct statements, but reason does not explain the assertion.
(ii) Assertion and reason both are correct statements, and reason explain the assertion.
(iii) Both assertion and reason are the wrong statements.
(iv) The assertion is correct statement and reason is the wrong statement.
(v) The assertion is the wrong statement and reason is the correct statement.

Answer:

The answer is the option (ii). Rayon is semi-synthetic polymer and is taken as a better choice than cotton fabric because mechanical and aesthetic properties of cellulose can be improved by acetylation. Thus, both assertion and reason are correct with the latter being the correct explanation.

Question:47

In the following question a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
Assertion: Most of the Synthetic polymers are not biodegradable.
Reason: Polymerisation process induces toxic character in organic molecules.
(i) Assertion and reason both are correct statements, but reason does not explain the assertion.
(ii) Assertion and reason both are correct statements, and reason explain the assertion.
(iii) Both assertion and reason are the wrong statements.
(iv) The assertion is correct statement and reason is the wrong statement.
(v) The assertion is the wrong statement and reason is the correct statement.

Answer:

The answer is the option (iv). Most of the synthetic polymers are non-biodegradable in nature i.e. they are not degraded by enzymatic, hydrolytic and environmental oxidation. Polymerisation process does not induce toxic characters in organic molecules.

Question:48

In the following question a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
Assertion: Olefinic monomers undergo addition polymerisation.
Reason: Polymerisation of vinyl chloride is initiated by peroxides/persulphates.
(i) Assertion and reason both are correct statements, but reason does not explain the assertion.
(ii) Assertion and reason both are correct statements, and reason explain the assertion.
(iii) Both assertion and reason are the wrong statements.
(iv) The assertion is correct statement and reason is the wrong statement.
(v) The assertion is the wrong statement and reason is the correct statement.

Answer:

The answer is the option (i). Olefinic monomers like ethene undergo addition polymerisation. The monomers used in addition polymerisation reaction are unsaturated compounds like alkenes, alkadienes etc. The assertion and reason both are correct statements but the reason does not explain the assertion.

Question:49

In the following question a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
Assertion: Polyamides are best used as fibres because of high tensile strength.
Reason: 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.
(i) Assertion and reason both are correct statements, but reason does not explain the assertion.
(ii) Assertion and reason both are correct statements, and reason explain the assertion.
(iii) Both assertion and reason are the wrong statements.
(iv) The assertion is correct statement and reason is the wrong statement.
(v) The assertion is the wrong statement and reason is the correct statement.

Answer:

The answer is the option (ii). Polyamides are best-used fibers because they have high tensile strength. They have closely packed chains and increased crystalline character due to presence of strong inter molecular forces like hydrogen bonding.

Question:50

In the following question a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
Assertion: For making rubber synthetically, isoprene molecules are polymerised.
Reason: Neoprene (a polymer of chloroprene) is a synthetic rubber.
(i) Assertion and reason both are correct statements, but reason does not explain the assertion.
(ii) Assertion and reason both are correct statements, and reason explain the assertion.
(iii) Both assertion and reason are the wrong statements.
(iv) The assertion is correct statement and reason is the wrong statement.
(v) The assertion is the wrong statement and reason is the correct statement.

Answer:

(v) Isoprene (2-methyl-1,3-butadiene) molecule is the monomer for natural rubber. Neoprene (a polymer of chloroprene) is a synthetic rubber.

Question:51

In the following question a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
Assertion: Network polymers are thermosetting.
Reason: Network polymers have high molecular mass.
(i) Assertion and reason both are correct statements, but reason does not explain the assertion.
(ii) Assertion and reason both are correct statements, and reason explain the assertion.
(iii) Both assertion and reason are the wrong statements.
(iv) The assertion is correct statement and reason is the wrong statement.
(v) The assertion is the wrong statement and reason is the correct statement.

Answer:

The answer is the option (i). Network polymers are thermosetting and have high molecular mass. However, the reason they are thermosetting is because of extensive cross-linking during polymerisation and not because of higher molecular mass.

Question:52

In the following question a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
Assertion: Polytetrafluoroethene is used in making non-stick cookware.
Reason: Fluorine has the highest electronegativity.
(i) Assertion and reason both are correct statements, but reason does not explain the assertion.
(ii) Assertion and reason both are correct statements, and reason explain the assertion.
(iii) Both assertion and reason are the wrong statements.
(iv) The assertion is correct statement and reason is the wrong statement.
(v) The assertion is the wrong statement and reason is the correct statement.

Answer:

The answer is the option (i). Polytetrafluoroethene or Teflon is used in making nonstick cookware, as it is chemically inert, resistant to attack by corrosive reagents and thermally stable.

NCERT Exemplar Class 12 Chemistry Solutions Chapter 1: Long Answer Type

Question: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 non-biodegradable as they are resistant to environmental degradation process. They form a major share of the polymer solid waste material.
Biopolymers are natural polymers of amino acids or carbohydrates, linked together by peptide or glycosidic linkages. They are found in plants and animals.

Biopolymer may or may not be biodegradable. For example: while protein and starch are biodegradable, keratin is not. Biodegradable polymer is polymers which are not resistant to environmental degradation process, e.g., DHBV nylon-2, nylon-6. Both the biodegradable polymers and biopolymers contain similar functional group.

Question:54

Differentiate between rubbers and plastics on the basis of intermolecular forces.

Answer:

Rubber
Plastics
The molecule consists of chains held together by weak Van Der Waals interaction.
Intermolecular forces of attarction intermediate between elastomers and fibre.
Coiled structure
Linear or slightly branched long chain
Returns to its original shape, size and length after being stretched.
Not really elastic in nature but capable of softening on heating and hardening on cooling.

Question:55

Phenol and formaldehyde undergo condensation to give a polymar (A) which on heating with formaldehyde gives a thermosetting polymer (B). Name the polymers. Write the reactions involved in the formation of (A). What is the structural difference between two polymers?

Answer:

Polymer ‘A’ in the question is Novalac and ‘B’ is bakelite. The reactions involved are:

The main structural difference between them is that novolac is a linear chain polymer while bakelite is a cross-linked polymer.

Question:56

Low-density polythene and high-density polythene, both are polymers of ethane, but there is marked difference in their properties. Explain.

Answer:

LDP
HDP
Formed at a temperature of 350 K to 570 K and very high pressure of about 1000-2000 atm.
The temperature of about 333 K to 343 K and a pressure of 6-7 atm is required.
It is obtained by free-radical addition and has a highly branched structure.
It has straight linear molecules and a high density.
Chemically inert and tough but flexible.
Chemically inert.
Tougher and harder than LDP

Question:57

Which of the following polymers soften on heating and harden on cooling? What are the polymers with this property collectively called? What are the polymers with this property collectively called? What are the structural similarities between such polymers? Bakelite, urea-formaldehyde resin, polythene, polyvinyl, polystyrene.

Answer:

Thermoplastic polymers soften on heating and harden on cooling. Polythene, polyvinyl and polystyrene are thermoplastic polymers. Their intermolecular force of attraction is somewhere between elastomers and fibres. They soften on heating and harden on cooling.
Bakelite, urea-formaldehyde resin are examples of thermosetting polymers. They are cross-linked and cannot be reused.

Major Topics and Subtopics in NCERT Exemplar Class 12 Chemistry Chapter 15 Solutions

  • Classification of Polymers
  • Classification Based on Source
  • Classification Based on Structure of Polymers
  • Classification Based on Mode of Polymerisation
  • Classification Based on Molecular Forces
  • Classification Based on Growth Polymerisation
  • Types of Polymerisation Reactions
  • Addition Polymerisation or Chain Growth Polymerisation
  • Condensation Polymerisation or Step Growth polymerization
  • Copolymerisation
  • Rubber
  • Molecular Mass of Polymers
  • Biodegradable Polymers
  • Polymers of Commercial Importance
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Class 12 Chemistry NCERT Exemplar Solutions Chapter 15 - Learning Outcomes

NCERT exemplar Class 12 Chemistry chapter 15 solutions Polymers have a diverse range of industrial and commercial uses. Industries like automotive, aerospace, electronics, packaging, and medical use polymers' adaptability and flexibility. They are used in drug delivery, biometric sensors, genetic engineering, aerospace engineering, and cosmetics. The wide range of polymers is still expanding and NCERT exemplar solutions for Class 12 Chemistry chapter 15 can be really helpful in understanding all these.

They have been used in sports, molecular recognition, water purification, biopolymers to save the environment, bulletproof vests, fire resistance, holography, renewable biomass applications, and 3D printing.

Without polymers, our lives would not have been so easy going and fast. From plastic packaging to huge rocket structures, polymers have always been the backbone of many major industries.

NCERT Exemplar Class 12 Chemistry Solutions

Important Topics in NCERT Exemplar Class 12 Chemistry Solutions Chapter 15

  • Class 12 Chemistry NCERT exemplar solutions chapter 15 has detailed that Classification of Polymers, Types of Polymerisation Reactions, Copolymerisation, Rubber, Molecular Mass of Polymers, Biodegradable Polymers, and Polymers of Commercial Importance are important topics which students should pay extra attention to.
  • NCERT exemplar solutions for Class 12 Chemistry chapter 15 introduces you to terms like polymer, monomer, and polymerization, help you find the difference between different polymer types, study respective monomers and their reactions to form polymers, and the preparation of synthetic polymers and their properties, and in turn, realizing the importance of polymers in our daily life.

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Frequently Asked Questions (FAQs)

1. What all things one will learn from these NCERT exemplar Class 12 Chemistry solutions chapter 15?

Class 12 Chemistry NCERT exemplar solutions chapter 15 help in learning, the process of polymerization, the types of polymerization, the source of polymers, the types of polymers, the properties, and natural polymers. 

2. Are these NCERT exemplar Class 12 Chemistry chapter 15 solutions helpful for the entrance exam?

Yes, these solutions are of major importance if a student is planning to appear in any entrance exam whether engineering or medical.

3. What all questions are included in these solutions?

The NCERT exemplar solutions for Class 12 Chemistry chapter 15 include all the questions present in the main exercise.

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Questions related to CBSE Class 12th

Have a question related to CBSE Class 12th ?
quartely question paper for mathematics cbse

Hello there! Thanks for reaching out to us at Careers360.

Ah, you're looking for CBSE quarterly question papers for mathematics, right? Those can be super helpful for exam prep.

Unfortunately, CBSE doesn't officially release quarterly papers - they mainly put out sample papers and previous years' board exam papers. But don't worry, there are still some good options to help you practice!

Have you checked out the CBSE sample papers on their official website? Those are usually pretty close to the actual exam format. You could also look into previous years' board exam papers - they're great for getting a feel for the types of questions that might come up.

If you're after more practice material, some textbook publishers release their own mock papers which can be useful too.

Let me know if you need any other tips for your math prep. Good luck with your studies!

Read Complete Answer
Jefferson 25 September,2024
i have taken admission in clg after my campartment exam in chemistry along with the neet 2025 preperation but unfortunately i again got campartment after doing all this preparation i got 15 marks only now I can't able to think what should I do next.

It's understandable to feel disheartened after facing a compartment exam, especially when you've invested significant effort. However, it's important to remember that setbacks are a part of life, and they can be opportunities for growth.

Possible steps:

  1. Re-evaluate Your Study Strategies:

    • Identify Weak Areas: Pinpoint the specific topics or concepts that caused difficulties.
    • Seek Clarification: Reach out to teachers, tutors, or online resources for additional explanations.
    • Practice Regularly: Consistent practice is key to mastering chemistry.

  2. Consider Professional Help:

    • Tutoring: A tutor can provide personalized guidance and support.
    • Counseling: If you're feeling overwhelmed or unsure about your path, counseling can help.

  3. Explore Alternative Options:

    • Retake the Exam: If you're confident in your ability to improve, consider retaking the chemistry compartment exam.
    • Change Course: If you're not interested in pursuing chemistry further, explore other academic options that align with your interests.

  4. Focus on NEET 2025 Preparation:

    • Stay Dedicated: Continue your NEET preparation with renewed determination.
    • Utilize Resources: Make use of study materials, online courses, and mock tests.

  5. Seek Support:

    • Talk to Friends and Family: Sharing your feelings can provide comfort and encouragement.
    • Join Study Groups: Collaborating with peers can create a supportive learning environment.

Remember: This is a temporary setback. With the right approach and perseverance, you can overcome this challenge and achieve your goals.

I hope this information helps you.







Read Complete Answer
Kanishka kaushikii 17 September,2024
i scored 84 percent in cbse 2 years ago.Am i eligible for medhavi scholarship if give 12th again after 2 drop years and will got 75+ in mpboard

Hi,

Qualifications:
Age: As of the last registration date, you must be between the ages of 16 and 40.
Qualification: You must have graduated from an accredited board or at least passed the tenth grade. Higher qualifications are also accepted, such as a diploma, postgraduate degree, graduation, or 11th or 12th grade.
How to Apply:
Get the Medhavi app by visiting the Google Play Store.
Register: In the app, create an account.
Examine Notification: Examine the comprehensive notification on the scholarship examination.
Sign up to Take the Test: Finish the app's registration process.
Examine: The Medhavi app allows you to take the exam from the comfort of your home.
Get Results: In just two days, the results are made public.
Verification of Documents: Provide the required paperwork and bank account information for validation.
Get Scholarship: Following a successful verification process, the scholarship will be given. You need to have at least passed the 10th grade/matriculation scholarship amount will be transferred directly to your bank account.

Scholarship Details:

Type A: For candidates scoring 60% or above in the exam.

Type B: For candidates scoring between 50% and 60%.

Type C: For candidates scoring between 40% and 50%.

Cash Scholarship:

Scholarships can range from Rs. 2,000 to Rs. 18,000 per month, depending on the marks obtained and the type of scholarship exam (SAKSHAM, SWABHIMAN, SAMADHAN, etc.).

Since you already have a 12th grade qualification with 84%, you meet the qualification criteria and are eligible to apply for the Medhavi Scholarship exam. Make sure to prepare well for the exam to maximize your chances of receiving a higher scholarship.

Hope you find this useful!

Read Complete Answer
Yuvan 30 August,2024
i upload 12th board result screenshot in ncweb form from the cbse site so it is valid

hello mahima,

If you have uploaded screenshot of your 12th board result taken from CBSE official website,there won,t be a problem with that.If the screenshot that you have uploaded is clear and legible. It should display your name, roll number, marks obtained, and any other relevant details in a readable forma.ALSO, the screenshot clearly show it is from the official CBSE results portal.

hope this helps.

Read Complete Answer
Ashvadha 12 July,2024
Kya mujhe class 12 ka important question milega jo exam mai per year puche jate hai

Hello Akash,

If you are looking for important questions of class 12th then I would like to suggest you to go with previous year questions of that particular board. You can go with last 5-10 years of PYQs so and after going through all the questions you will have a clear idea about the type and level of questions that are being asked and it will help you to boost your class 12th board preparation.

You can get the Previous Year Questions (PYQs) on the official website of the respective board.

I hope this answer helps you. If you have more queries then feel free to share your questions with us we will be happy to assist you.

Thank you and wishing you all the best for your bright future.

Read Complete Answer
kumardurgesh1802 10 July,2024
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Popular CBSE Class 12th Questions

A block of mass 0.50 kg is moving with a speed of 2.00 ms-1 on a smooth surface. It strikes another mass of 1.00 kg and then they move together as a single body. The energy loss during the collision is

Option 1)

0.34\; J

 Option 2)

0.16\; J
Option 3)

1.00\; J

 Option 4)

0.67\; J
Read More

A person trying to lose weight by burning fat lifts a mass of 10 kg upto a height of 1 m 1000 times.  Assume that the potential energy lost each time he lowers the mass is dissipated.  How much fat will he use up considering the work done only when the weight is lifted up ?  Fat supplies 3.8×107 J of energy per kg which is converted to mechanical energy with a 20% efficiency rate.  Take g = 9.8 ms−2 :

Option 1)

2.45×10−3 kg

 Option 2)

 6.45×10−3 kg
Option 3)

 9.89×10−3 kg

 Option 4)

12.89×10−3 kg

 
Read More

An athlete in the olympic games covers a distance of 100 m in 10 s. His kinetic energy can be estimated to be in the range

Option 1)

2,000 \; J - 5,000\; J

 Option 2)

200 \, \, J - 500 \, \, J
Option 3)

2\times 10^{5}J-3\times 10^{5}J

 Option 4)

20,000 \, \, J - 50,000 \, \, J
Read More

A particle is projected at 600   to the horizontal with a kinetic energy K. The kinetic energy at the highest point

Option 1)

K/2\,

 Option 2)

\; K\;
Option 3)

zero\;

 Option 4)

K/4
Read More

In the reaction,

2Al_{(s)}+6HCL_{(aq)}\rightarrow 2Al^{3+}\, _{(aq)}+6Cl^{-}\, _{(aq)}+3H_{2(g)}

Option 1)

11.2\, L\, H_{2(g)}  at STP  is produced for every mole HCL_{(aq)}  consumed

 Option 2)

6L\, HCl_{(aq)}  is consumed for ever 3L\, H_{2(g)}      produced
Option 3)

33.6 L\, H_{2(g)} is produced regardless of temperature and pressure for every mole Al that reacts

 Option 4)

67.2\, L\, H_{2(g)} at STP is produced for every mole Al that reacts .
Read More

How many moles of magnesium phosphate, Mg_{3}(PO_{4})_{2} will contain 0.25 mole of oxygen atoms?

Option 1)

0.02

 Option 2)

3.125 × 10-2
Option 3)

1.25 × 10-2

 Option 4)

2.5 × 10-2
Read More

If we consider that 1/6, in place of 1/12, mass of carbon atom is taken to be the relative atomic mass unit, the mass of one mole of a substance will

Option 1)

decrease twice

 Option 2)

increase two fold
Option 3)

remain unchanged

 Option 4)

be a function of the molecular mass of the substance.
Read More

With increase of temperature, which of these changes?

Option 1)

Molality

 Option 2)

Weight fraction of solute
Option 3)

Fraction of solute present in water

 Option 4)

Mole fraction.
Read More

Number of atoms in 558.5 gram Fe (at. wt.of Fe = 55.85 g mol-1) is

Option 1)

twice that in 60 g carbon

 Option 2)

6.023 × 1022
Option 3)

half that in 8 g He

 Option 4)

558.5 × 6.023 × 1023
Read More

A pulley of radius 2 m is rotated about its axis by a force F = (20t - 5t2) newton (where t is measured in seconds) applied tangentially. If the moment of inertia of the pulley about its axis of rotation is 10 kg m2 , the number of rotations made by the pulley before its direction of motion if reversed, is

Option 1)

less than 3

 Option 2)

more than 3 but less than 6
Option 3)

more than 6 but less than 9

 Option 4)

more than 9
Read More

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News and Notifications
CBSE board exams 2025 from February 15; Class 10, 12 subject-wise marks distribution
October 24, 2024 - 11:43 AM IST
CBSE Date Sheet 2025: Class 10, 12 board exam dates soon on cbse.gov.in; previous trends, sample papers
October 23, 2024 - 03:21 PM IST
CBSE Board Exams 2025: 75% attendance must for students to be eligible, reiterates board
October 11, 2024 - 08:42 AM IST
CBSE Class 10, 12 practical exams 2025 for winter-bound schools from November 5
October 11, 2024 - 07:26 AM IST
CBSE Date Sheet 2025: When to expect Class 10, 12 board exam time table?
October 07, 2024 - 01:58 PM IST
CBSE introduces CCTV policy in board exams 2025; schools fixed as centres must have facility
September 27, 2024 - 04:37 PM IST
CBSE gives parents, schools till October 16 to register students in Classes 9, 11
September 21, 2024 - 05:15 PM IST

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