Polymers Class 12 Chemistry Exam Questions

Please refer to the below Polymers important questions for Class 12 Chemistry. These questions and answers have been prepared as per the latest NCERT Book for Class 12 Chemistry. Students should go through chapter wise Class 12 Chemistry Important Questions designed as per the latest examination pattern issued by CBSE.

Question. What is the difference between the two notations : 
nylon – 6 and nylon – 6,6 ?  
Answer : Nylon 6 is obtained from the monomer caprolactam which contains 6 carbon atoms. Nylon 6,6 is a condensation polymer of hexamethylene diamine and adipic acid. Both the monomers have 6 carbon atoms each.

Question. Differentiate between molecular structures and behaviours of thermoplastic and thermosetting polymers. Give one example of each type. 
Answer : Thermoplastics : Thermoplastics are linear or slightly branched polymers which can be repeatedly softened on heating and hardened on cooling and hence can be used again and again without any change in chemical composition and mechanical strength.
Example : Polythene and polystyrene.
Thermosetting Polymers: Thermosetting polymers on heating in a mould get hardened and set and cannot be softned again. This hardening on heating is due to cross-linking between different polymer chains to give a three-dimensional network solid. 
Example : Bakelite.

Question. Write the name of monomers used for getting the following polymers :
(i) Teflon
(ii) Buna-N  
Answer : (i) Teflon : CF₂=CF₂
Tetrafluroethylene

(ii) Buna–N : CH₂=CH—CH=CH₂ and CH₂=CHCN
                     1,3–Butadiene             Acrylonitrile

Question. (i) What is the role of t-butyl peroxide in the polymerisation of ethene?
(ii) Identify the monomers in the following polymer :

Answer : (i) Polymerisation of ethene requires an initiator to start the polymerisation with free radical mechanism. Thus, peroxide like t-butyl peroxide decomposes to give free radical that initiates the reaction.
(ii) Hexamethylene diamine and adipic acid.

Question. Based on molecular forces what type of polymer is neoprene?  
Answer : Elastomer.

Question. Write the name of monomers used for getting the following polymers :
(i) Terylene
(ii) Nylon-6,6 
Answer : (i) Terephthalic acid and ethylene glycol..
(ii)

Question. Write the monomers which are used for the synthesis of the following polymers :
(i) Terylene
(ii) Polythene
(iii) Bakelite
Indicate the type of polymerisation for each which forms the polymer.  
Answer : (i) Terephthalic acid and ethylene glycol. It is a condensation polymer.
(ii) Monomer of polythene is ethene. It is an addition polymer.
(iii)

It is a condensation polymer.

Question. Which of the following is a fibre?
Nylon, Neoprene, PVC  
Answer : Nylon is a fibre.

Question. How are thermosetting polymers different from thermoplastic polymers? 
Answer : Thermoplastics : Thermoplastics are linear or slightly branched polymers which can be repeatedly softened on heating and hardened on cooling and hence can be used again and again without any change in chemical composition and mechanical strength.
Example : Polythene and polystyrene.
Thermosetting Polymers: Thermosetting polymers on heating in a mould get hardened and set and cannot be softned again. This hardening on heating is due to cross-linking between different polymer chains to give a three-dimensional network solid. 
Example : Bakelite.

Question. What is the difference between elastomers and fibres? Give one example of each.  
Answer : (i) In elastomers polymer chains are held together by weakest intermolecular forces.
These have elastic properties. e.g. Buna-N, Buna-S.
(ii) In fibres polymer chains are held together by strong intermolecular forces like hydrogen bonding.
These have high tensile strength.
e.g., Terylene, Nylon 6,6, etc.

Question. (i) What is the role of sulphur in the vulcanisation of rubber?
(ii) Identify the monomers in the following polymer :

Answer : Vulcanisation is a process of heating natural rubber with sulphur and an appropriate additive to modify its properties.
It gives greater elasticity and ductility. Sulphur forms cross linked network which gives mechanical strength to the rubber.

(ii) Terephthalic acid and ethylene glycol.

Question. Which of the following is a natural polymer?
Buna-S, Proteins, PVC  
Answer : Proteins are natural polymers.

Question. Differentiate between thermoplastic and thermosetting polymers. Give one example of each.  
Answer : Thermoplastics : Thermoplastics are linear or slightly branched polymers which can be repeatedly softened on heating and hardened on cooling and hence can be used again and again without any change in chemical composition and mechanical strength.
Example : Polythene and polystyrene.
Thermosetting Polymers: Thermosetting polymers on heating in a mould get hardened and set and cannot be softned again. This hardening on heating is due to cross-linking between different polymer chains to give a three-dimensional network solid. 
Example : Bakelite.

Question. Define the term, ‘homopolymerisation’ giving an example.  
Answer : A polymer made by polymerisation of a single monomer is known as homopolymer and the process is known as homopolymerisation For e.g., Polythene made by polymerisation of ethene molecules.
      nCH₂ = CH₂ → (— CH₂—CH₂ —)_n
        Ethene                 Polythene 

Question. Define thermoplastic and thermosetting polymers. Give one example of each. 
Answer : Thermoplastics : Thermoplastics are linear or slightly branched polymers which can be repeatedly softened on heating and hardened on cooling and hence can be used again and again without any change in chemical composition and mechanical strength.
Example : Polythene and polystyrene.
Thermosetting Polymers: Thermosetting polymers on heating in a mould get hardened and set and cannot be softned again. This hardening on heating is due to cross-linking between different polymer chains to give a three-dimensional network solid. 
Example : Bakelite.

Question. What are addition polymers? How are the two types of addition polymers different from each other? Give one example of each type. 
Answer : Polymers which are formed by the repeated addition reaction of unsaturated monomer molecules are called the addition polymers.
The two types of addition polymers are :
(i) Homopolymers : The addition polymers formed by the polymerisation of a single compound are called homopolymers. e.g., polyethene.
      nCH₂ = CH₂ → (— CH₂—CH₂ —)_n
       Ethene              Polythene
(ii) Copolymers : The polymers made by addition polymerisation from two different compounds are known as copolymers. e.g., Buna-S.

Question. Find the main difference between them 
(i) Thermoplastic polymers
(ii) Thermosetting polymers  
Answer : Thermoplastics : Thermoplastics are linear or slightly branched polymers which can be repeatedly softened on heating and hardened on cooling and hence can be used again and again without any change in chemical composition and mechanical strength.
Example : Polythene and polystyrene.
Thermosetting Polymers: Thermosetting polymers on heating in a mould get hardened and set and cannot be softned again. This hardening on heating is due to cross-linking between different polymer chains to give a three-dimensional network solid. 
Example : Bakelite.

Question. Name the polymer which is used for making non-stick cooking utensils.  
Answer : Teflon [—CF₂—CF₂ —]_n

Question. Explain the term ‘copolymerisation’ and give two examples of copolymerization.  
Answer : Copolymerization : When the polymers are synthesised by polymerization of two or more than two different monomers then this process is called as copolymerization. example,
(i) Styrene butadiene rubber (SBR) :

Question. Write the structures of monomers used in the preparation of
(a) Teflon
(b) PMMA 
Answer : (i) Teflon : CF₂=CF₂
Tetrafluroethylene

(ii) PMMA : CH₂=C—COOCH₃
                          l
                        CH₃
               Methyl methacrylate

Question. Distinguish between homopolymers and copolymers.
Give one example of each. 
Answer : Homopolymer : A polymer made by polymerisation of a single monomer is known as homopolymer and the reaction is called homopolymerisation. 
e.g. Polythene made by ethene molecules.
    nCH₂ = CH₂ → (— CH₂—CH₂ —)_n
     Ethene           Polythene (homopolymer)
Copolymer : A polymer made by polymerisation of two or more different monomers is called copolymer and the reaction is called copolymerisation. When styrene and butadiene are polymerised together, a  polymer called styrene-butadiene rubber is formed

Question. Write the (i) structure and (ii) one use of each of the following polymers :
(a) PVC
(b) Urea-formaldehyde resin
(c) Bakelite  
Answer : (i) PVC

Used in making electrical switches and handles of utensils.

Question. What does the part ‘6,6’ mean in the name nylon-6, 6?  
Answer : In nylon 6, 6, designation ‘6, 6’ mean that both the monomers hexamethylene diamine and adipic acid contain six carbon atoms each.

Question. Give names of the monomers of the following polymers :
(i) Neoprene
(ii) Polystyrene
(iii) Polypropene 
Answer :

Question. Arrange the following polymers in the increasing order of their intermolecular forces :
Terylene, Polythene, Neoprene. 
Answer : Neoprene < Polythene < Terylene.

Question. What does ‘6,6’ indicate in the name nylon-6,6? 
Answer : In nylon 6, 6, designation ‘6, 6’ mean that both the monomers hexamethylene diamine and adipic acid contain six carbon atoms each.

Question. What are biodegrable and non-biodegradable polymers? Give one example of each class. 
Answer :

Question. Write the names and structures of the monomers of the following polymers :
(i) Nylon 6, 6
(ii) Neoprene 
Answer : 

Question. What is a biodegradable polymer? Give an example of a biodegradable aliphatic polyester. 
Answer : Biodegradable Polymers : The natural polymer, which disintegrates by itself or by micro-ogranisms within certain period of time is called biodegradable polymer, e.g., PHBV (poly–b–hydroxybutyrate–co–b–hydroxyvalerate), Nylon 2–nylon 6.

Question. Write the name of monomers used for getting the following polymers :
(i) Bakelite
(ii) Neoprene 
Answer : (i) Bakelite : Formaldehyde (HCHO) and Phenol (C₆H₅OH)
(ii)

Question. Write chemical equations to form the following :
(i) Nylon-6
(ii) Nylon-6,6
(iii) Polythene  
Answer : (i) Nylon–6 : It is formed by self condensation of caprolactam in the presence of water.