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Ramakrishna Vivekananda Mission Vidyabhawan (H.S.UNIT)
Syllabus for Pre-Test Exam 2020
Class-XII Subject- Chemistry
(Bengali Version)
Chapter 1: ������� ���
Chapter 2: ������� ��ব�� ���
Chapter 3: �����
Chapter 4: ��ব-������
Chapter 5: d � f �� �������
Chapter 6: ������������� ব!
��������������
Chapter 7: ���������,�#�� ব! $%����
Chapter 8: &ব�
Ramakrishna Vivekananda Mission Vidyabhawan (H.S.UNIT)
Syllabus for Pre-Test Exam 2020
Class-XII Subject- Chemistry
(English Version)
Chapter 1: Surface Chemistry
Chapter 2: Chemistry In Everyday Life
Chapter 3: Polymers
Chapter 4: Biomolecules
Chapter 5: d & f Block Elements
Chapter 6: Haloalkanes & Haloarenes
Chapter 7: Alcohols,Phenol & Ethers
Chapter 8: Solution
POLYMERS • Polymers:
Polymers are high molecular mass substance consisting of large number of repeating structural units. As polymers are single, giant molecules i.e. big size molecules, they are also called macromolecules.
• Monomers: The simple molecules which combine to form polymers by forming single or
multiple bonds are called monomers.
• Polymerization: The process of formation of polymers from respective monomers is called polymerization
• ����� ��� ��� �� �� ��������� ��� ���� ���� �������� ����� ��� �� ��� । • "# ��� $�% $�% ��� � �� #�& ��#' ��� �� ���� �( ������� ��� �� ��� । • ��� �� ")�� ��� ���*�+� �,���� ��� �� ���� �#'।
• Classification of Polymers:
Based on source of availability (./��� .�� �0�� ���) Natural polymers: Polymers obtained from nature, mostly plants and animals.
+2���� �)3�/ 4��2 �� .�5���� ")�� �� ��� �� "� 4������ ��� �� ���। Examples – Cellulose, starch, etc. Synthetic polymers: Polymers prepared in laboratory. ���#'������ ���6 0��� "# ��� �� 7��� ��� �#' ����� ���6 ��� �� ���। Examples – Teflon, Nylon 6,6 Semi synthetic polymers: Polymers derived from naturally occurring polymers by carrying out chemical modifications. 4����+�� ��� �� ")�� ����#'��� �����3��� ���� "# ��� �� ��� �#', ����� �83-���6 ��� �� ���। Examples – Rayon (cellulose acetate), cellulose nitrate, etc. Based on the structure of polymer(����� .�� �0�� ���)
Linear polymers: Polymer consists of long and straight chains. ��� �� ���9��� ���� ���:���� �2�3 �;���<� "# ��� �� ��� ���� �#' ���� 7���� ��� �� ���। Examples – High density polythene, polyvinyl chloride, etc.
Branched chain polymers: Polymers contains linear chains having some branches. "#�� ��� ���� �;��� ��= ����8� ���#�& �;� � #�& ��#' ��� �� ��� ���, ����� ���#�& ��� �� ���। Examples – Low density polythene Cross linked or network polymers: Polymers in which monomer units are cross linked together to form a 3 dimensional network polymers. ���#�& ��� ���� ���9��� ���� >� ��?��� ��= #�& ��#' �@'���@' �A� ��� ���� "# ��� ���� ��� �#' ���� �@'���@'#�& �� +��� ��� �� ���। Examples – Bakelite,Melamine,etc.
Based on the mode of polymerization Addition polymers: Polymers are formed by the repeated addition of monomers with double and triple bonds. ��� �� ���9�� �;� ���B#'�� ���� ������ ����#'��� � #�� ��<�#' "# ��� �� ��� ���, ����� �;� �� #�� ��� �� ���। It is further classified into,
Homopolymers:Polymers formed by the polymerisation of a single monomeric species. Examples – Polythene, Polystyrene. Copolymers:Polymers formed by addition polymerisation of two different monomers. �� 4��� ��� �� ���� ���� ��� ���� "��� � ��� �� ��� �� �0C 8���� ��� �� ���� ���� ��� ���� "����� �� ���। Examples – Buna-S, Buna –N.
Condensation polymers: Polymers formed by repeated condensation reaction between two different bi-functional or tri-functional monomeric units with elimination of simple
molecules. D* �� ��� "�� ��#3��2 >�� ��<� ��� �� 9�� ��?� 8��� 8��� ���B#'�#' ����#'���0��� #�& ��#' "# ��� �� ��� ���, ���� � ��� �� ���@���� ��� �� ���।
Examples – Nylon 6, 6, Nylon 6.
Based on effect of heat(����� 40���� .�� �0�� ���) Thermoplastic polymers: Polymers are held by intermolecular forces which are in between those of elastomers and fibres. These polymers are capable of repeated softening on heating and hardening on cooling. Examples – Polythene, Polystyrene. "#�� ��� �� ��� 4�(��� � �2#' �#' ��E ��� ������� �����#' ���� ��F� 4�G �#' �� �* �,�� #�� ��� ���� 8 3 �+�( "��� ����8���� ��� #�#', ����� )�� 3�H��I� ��� �� ���। .�����-���I�*���, ���*�)���,����0��*� "K���*@ 40���। Thermosetting polymers: Polymers are cross linked or heavily branched molecules, which on heating undergo extensive cross linking in moulds and eventually undergo a permanent change. Examples – Bakelite, Urea-formaldelyde resins. "#�� ��� �� ��� 4���� � �2#' �� ��� ������� �����#' ���� ��F� 4�G �#', ��E ���2#'��� ��� 4�(��� �����#' � �2#' �#' ��, ����� )�� 3����< ��� �� ���। .�����-��L�& ����I��, "M��-M 3���@��*@ "��+�
Commercially important polymers along with their structures and uses
1. Low density polythene (LDP) is a polymer of ethene.
It is used in the insulation of electricity carrying wires and manufacture of squeeze bottles. ��< *�)��� ��N ��� ��� ��� ��,#� ��D�/ ���2 ����� �P�� Q � �2( "���� 4R���� ���S� �(।
2. High density polythene(HDP) is a polymer of ethene.It is used for manufacturing buckets, dustbins, bottles, pipes, etc ��< *�)��� .T ��� ��� ��� �� ��< ����� ,@�I���,"����,��*� *����� 7��� ���� ���S� �#'
3. Polytetrafluoroethene (Teflon) It is used in making oil seals and gaskets and also used for non – stick surface coated utensils "<M���� ��� �� �� "<U�V�Q��� *�)� । ��#'� ���,������< �� ���I� �����6 4R���� ������ ��� �#'
4. Polyacrylonitrile is a polymer of acrylonitrile. It is used as a substitute for wool in making commercial fibres such as orlon or dacron. ������B�*��� ��*U�*� ���� ���B�*�����*U�*� �� ��� ��। ��< �����+�� ���6 �E 4R���� ���+ ����
5. Polyamides: Polymers possess amide linkage (-CONH-) in chain. These polymers are popularly known as nylons. Examples: a) Nylon 6, 6: It is prepared by the condensation polymerisation of hexamethylenediamine with adipic acid under high pressure and at high temperature.
It is used in making sheets, bristles for brushes and in textile industry. b) Nylon 6: It is obtained by heating caprolactum with water at a high temperature It is used for the manufacture of tyre cords, fabrics and ropes ��� ��� �*@ 9�� �� � � ��� �� #�� �8� ��� �*@ �� ��+ ��3 �� �9����� ��8���0��� ��*�� ���, "�W�� �)��� @�* ���� � �� ����@��� �����@ �� � ��� ��� �� ���� ��*��-6,6 �9�� ��*�� X��� Y� �� ���� �� ��@' 4R���� ������ ��� �#' ��*��-6 ���� caprolactum �� ���< ��� ��,caprolactum ���) +� � ��#' .�G ���� �* ��� ���< ./�C �#', ��< ���@'� <�#'��,+� ����@' �� ��@' 7����� ���+ ����
6. Polyesters: These are the polycondensation products of dicarboxylic acids and diols Example: Terylene or DacronIt is used to create resistance in polymerised product and is used in blending with cotton and wool fibres and also as glass reinforcing materials in safety helmets, etc. @�* ���3�W��� �����@ �� @�* �� �� ��� �� ���� ����#'I�� "<����� ��� ���� "��8 ���, ���� �� ����� � ���) � ��#' ���6 �E 4R� ���� ������ ��� �(।
7. Phenol – formaldehyde polymer (Bakelite and related polymers)
a. Bakelite: These are obtained by the condensation reaction of phenol with formaldehyde in the presence of either an acid or a base catalyst. The initial product could be a linear product,Novolac used in paints. �� ��� ��� �� �����@ Q $���� .��F���� "M�� Q M� ���@��*�@� � ���� �������*< 4R� ��� �#' । 4�)� �0��� ./�C "#Z��< �� ��0�����,#� � 4R���� ������ ��� �#'। b. Novolac on heating with formaldehyde forms Bakelite.
It is used for making combs, phonograph records, electrical switches and handles of various utensils. ��0����� "� .�G ���� �������*< ��Q#'� #�#' "#�< *����U� ��*X �� ���0C ������6� ���� 7����� ������ ��� �#' ।
c. Melamine – formaldehyde polymer: Melamine formaldehyde polymer isformed by the condensation polymerisation of melamine and formaldehyde. It is used in the manufacture of unbreakable crockery. " �� �*� �� M� ���@��*�@� ��� �� ���� " �� �*�,��< ������ ��� �#' �� �0=�� ���� 4R���� Natural rubber: Natural rubber is a linear polymer of isoprene (2-methyl-1, 3-butadiene) and is also called as cis – 1, 4 – polyisoprene. ���6 ����� �� isoprene (2-methyl-1, 3-butadiene) �� "#Z��� ���< ����� ��। ����� ����� isoprene ���) ��� ��L�& ��� �� � ��#' ���6 ����� 4R� ��� �#'।
8. Synthetic rubber: Synthetic rubbers are either homopolymers of 1, 3 – butadiene derivatives or copolymers of 1, 3 – butadiene or its derivatives with another unsaturated monomer.
i. Neoprene or polychloroprene-It is used for manufacturing conveyor belts, gaskets and
hoses. ��Q�4� �� "K�����4��� ���< ��� �� "#�< ������<,"�����*��� 4R���� ������ ��� �#'
ii. Buna – N-It is used in making oil seals, tank lining, etc. because it is resistant to the action of petrol, lubricating oil and organic solvents
���0C 7+� %��� ���[� "��U���#'�� � ���) ���B#'� �� ���#' ��<�� ��#'� ��� ��*�� �� ������ ��*� 4R��� ���+ ������ ��� �#'
iii. Buna – S- It is used in speciality packaging, orthopaedic devices and in controlled release of drugs.
��<�� ������+ �� ���\ ���[� ��F � B�P ���0C #]���� �� ���0C ^[8 4R���� ������ ��� �#'
9. Terylene or Dacron: It is manufactured by heating a mixture of ethylene glycol and terephthalic acid at 420 to 460 K in the presence of zinc acetate-antimony trioxide catalyst.
420 ")�� 460 "���0� ._��( �+ � ������<< �� ����` �� U�* �W�*@ ����<��� .��F���� *�)��� a�*�� �� "<��)����� �����@ �� ���B#'�#' ��< 4R� ��� �#' ��< ������ ��� �#' । Vulcanisation of rubber: The process of heating a mixture of raw rubber with sulphur and an appropriate additive in a temperature range between 373 K to 415 K to improve upon physical properties like elasticity, strength etc. ������� "0Z� ��F� �����3��� +�� ��� ���M�� �)�� ��� "��� "#Z��� .��F���� .�G ��� �#' ��� ������� 0������*�+� ��� Biodegradable Polymers: Polymers which are degraded by microorganisms within a suitable period so that biodegradable polymers and their degraded products do not cause any serious effect on environment. Example: Poly –β-hydroxybutyrate – co- β-hydroxyvalerate (PHBV):
It is obtained by the copolymerisation of 3-hydroxybutanoic acid and 3 – hydroxypentanoic acid,Nylon 2–nylon 6: It is an alternating polyamide copolymer of glycine(H2N–CH2–COOH) and amino caproic acid (H2N (CH2)5 COOH)
"# ��� ��� �� ����3 � �(� �8� ���+2� ���� ���(��+� �( �� #���� ���(��+� � ������ "����� �b $����8� ��� �� ����� 7+����(�+��#��� ��� �� ���।�# �- Poly –β-hydroxybutyrate – co- β-hydroxyvalerate (PHBV):��< 3-hydroxybutanoic acid Q 3 – hydroxypentanoic acid �� ���< ����� ��। Nylon 2–nylon 6: ��< a�*��� �� ���� ��� ����4��(� ������@� ����� ��। 1. Distinguish between the terms homopolymer and copolymer and give an example of
each. ����� �� �� "����� ���� ��)3�� ��?.����� ��Q।
Homopolymer Copolymer
The polymers that are formed by the polymerization of a single monomer are known as homopolymers. In other words, the repeating
units of homopolymers are derived only from one monomer. For example, polythene is a
homopolymer of ethane. �� 4��� ��� �� ���� ���� ��� ���� "��� � ��� �� ���
The polymers whose repeating units are derived from two types of monomers are
known as copolymers. For example, Buna−S is a copolymer of 1, 3-butadiene and styrene.
�0C 8���� ��� �� ���� ���� ��� ���� "����� �� ���। 2. Give example of condensation polymer. What is the name of monomer of Teflon? ���< � ���
��� ���� .����� ��Q।�<M���� ��� �� "����<? Condensation polymer is nylon. The monomer of teflon is Tetra fluoro ethylene.
3. Define the term polymerisation. Name the monomers of of PET? ��� ���*�+���� � d� ��Q।PET �� ��� �� "����<?
Polymerization is the process of forming high molecular mass (103 − 107 u) macromolecules, which consist of repeating structural units derived from monomers. In a polymer, various monomer units are joined by strong covalent bonds.
Ethylene glycol and Terepthalic acid. *�)��� a�*�� �� "<��)����� �����@ "# ����#'��� ���B#'�#' �� �� ��� �� ��� #�& ��#' �������� Q .T ����� Q+���� ��� �� ��� ��� ���, ���� ��� ���*�+� ���B#'� ��� �#'। *�)��� a�*�� �� "<��)����� �����@। 4. Which type of polymer is starch and cellulose on basis of their sources? Why starch and cellulose are known as biopolymers? I�X3 Q "������+ �� 8���� ��� ��? ���� 7+� ��� �� ��� "��?
Starch and cellulose both are natural Polymers. They are known as bioPolymers as their present in human and plant body and control different biochemical reactions. I�X3 �� "������+ ���� 4������ ��� �� ��� ���0C +2����� .��F� ")�� ���0C +2� ����#'��� ���B#'� "� ��#']� ��� ��* ������ ���#'���� �� ���।
5. Write the IUPAC name of the monomer of natural rubber? 4������ ������� " ���� �� "����<? 2-methyl-1,3-butadiene 6. What are the monomers of nylon 6, 6? What does the term 6,6 stand for? Adipic acid and Hexamethylenediamine. As in both amine and carboxylic acid six carbon atoms are present, to represent those 6 carbon atoms in the monomers this is termed as 6,6. ����@��� ���@ �� "�W�� �)��� @�* ���� � "#���� ���� � �� ���3�W��� �����@ "#Z�D�<�� 6�< ��� ���3� �� ��� ��3 �� ��* D�< ��� ���� \’�< ��� ���3� �� ��� "� "��f����� +�� �* 6,6 g�< ������ ��� �#'
7. What are polyesters? Give example. ����I�� ��? .����� ��Q। The Polymers having –COO- in their chain are known as polyesters. PET is polyester. "# � h ��� ��� .��F� )��� ���� ����#'I�� ��� , PET ���< ����#'I�� 8. Can enzymes be termed as polymers? What are elastomers? ./��X��� �� ��� �� ��� #�(?���I ��
��? Enzymes are proteins having peptide as monomer. Hence they can be termed as polymers. The Polymers which which can be streched using force and after removal of the force it regains its former shape is known as elastomer. ./��X� ���� "�* 8���� "4��<� #�� ��� �� �� "��<�*@ ��* ������ ��� �� ��� #�#' "# � h ��� ���� Q�� ��� 4�#'�� ���� �� ����� �#' �� ��� �������� �� �>��3� ��F�#' �M�� #�#' ������� ���I �� ��� 9. Why Bakelite is thermosetting polymer? Name the monomer of neoprene? �������*< )� 3���< ��� �� "��? ��Q�4��� " ���� �� "����<? Bakelite polymer chain contains vertical cross linkages which on application of heat break and cannot be regained. Chloroprene is the monomer of neoprene. �������*< � .��F� �@'���@' � �#�����2 �A� 9�� ��� 4�#'��� "0�i #�#' �� "��< ��� �������� �� ����3��� ��� ���� �� ��* �������*< ���< )�� 3����< ��� �� ।"K�����4� �� ��Q�4��� ��� ��।
10. Explain the term copolymerisation and give two examples. The process of forming Polymers from two or more different monomer units is called copolymerization. � ����� 9j� �0C 8���� " ���� �� ���� "����� �� 4R��� �,���� "����� ���*�+�� ���। The process of forming polymer Buna−S from 1, 3-butadiene and styrene is an example of Copolymerization.
11. Write the monomers used for getting the following polymers.��N����� ��� �� 9��� " ���� �� 9��� �� "��। (i) Polyvinyl chloride (ii) Teflon (iii) Bakelite
Vinyl chloride (CH2=CHCl) Tetrafluoroethylene (CF2 = CF2) Formaldehyde (HCHO) and phenol (C6H5OH) 12. Write the name and structure of one of the common initiators used in free radical addition polymerisation. �& >�� ��� ���*�+�� � 4��k� ������ �� ������ ��� �(? One common initiator used in free radical addition polymerization is benzoyl peroxide. Its structure is given below.
13. Discuss the main purpose of vulcanisation of rubber.������� 0������*�+�� ��� �( "��?
Natural rubber though useful has some problems associated with its use. These limitations are discussed below: 1. Natural rubber is quite soft and sticky at room temperature. At elevated temperatures (> 335 K), it becomes even softer. At low temperatures (< 283 K), it becomes brittle. Thus, to maintain its elasticity, natural rubber is generally used in the temperature range of 283 K-335 K. 2. It has the capacity to absorb large amounts of water.
3. It has low tensile strength and low resistance to abrasion.
4. It is soluble in non-polar solvents.
5. It is easily attacked by oxidizing agents.
Vulcanization of natural rubber is done to improve upon all these properties. In this process, a mixture of raw rubber with sulphur and appropriate additive is heated at a temperature range between 373 K and 415 K.
4������ ����� �������#��� ���� +�� 0������*�+�� �,�� 4�#'�� ��� �#' । ��8��� ._��#' 4������ ����� �� �� X<X�< 4�����। .T ._��#' ��< ���� �� ��#' #�#' �� 4�#' ��� ��F�#' )��� ��* ��<� � �2#'�� Q �F��F����� �+�#' ����� +�� ������ 0������*�+� ��� �#' । 4������ ����� 4X�� ��� ��� +� "�[� ���� ���� �� ��< non-polar %���� %�20>� �#'। ��\�@'� ��< ���0C +��� ���)3 ���� �B�P ��� ���� ।�* � h �����8� �>� ���� +�� ������� 0������*�+�� �,�� 4�#'�� ��� �#'। 14. Write the names and structures of the monomers of the following polymers: . ��N����� ��� �� 9��� " ���� �� 9��� �� Q ��� "��। (i) Buna-S (ii) Buna-N
(iii) Dacron (iv) Neoprene
Polymer Monomer Structure of monomer
i
Buna-S
1, 3-butadiene
Styrene
ii
Buna-N
1, 3-butadiene
Acrylonitrile
iii
Neoprene
Chloroprene
iv
Dacron Ethylene glycol
Terephthalic acid
15.
(i)
(ii)
(i)
(ii) The monomers of the given polymeric structure
MCQ type questions:
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
Identify the monomer in the following polymeric
The monomers
The monomers of the given polymeric structure
MCQ type questions:
A high molecular weight
(.T ����� 9j� ��� ��������� ��� ���2� ��������� ��� �� (A) Polymer
Which of
(A) Proteins
Natural rubber
(A) Butadiene
Terylene is
(A) Benzoic
Which of
(A) Starch
Amongst
(A) PMMA
Which of the
(A) Buna
Which of
(A) Nylon
(C) Alkyd
Identify the monomer in the following polymeric
monomers
and hexamethylene diamine
The monomers of the given polymeric structure
MCQ type questions:
molecular weight
.T ����� 9j� ��� ��������� ��� ���2� ��������� ��� �� Polymer
of the following
Proteins
Natural rubber is a polymer
Butadiene
is a condensation
Benzoic acid
of the following is
Starch
Amongst the following,
PMMA
of the following is
Buna-S
of the following
Nylon
Alkyd resin
Identify the monomer in the following polymeric
of the given
and hexamethylene diamine
The monomers of the given polymeric structure
molecular weight molecule
.T ����� 9j� ��� ��������� ��� ���2� ��������� ��� �� (B) Macromolecule
following is not a biopolymer
(B) Nucleic
a polymer of
(B) Ethyne
condensation polymer of
(B) Phthalic
following is a synthetic polymer
(B) Silk
following, a homopolymer
(B) Bakelite
following is a copolymer.
(B) PAN
following is a linear
Identify the monomer in the following polymeric
given polymeric
and hexamethylene diamine
The monomers of the given polymeric structure
molecule which does
.T ����� 9j� ��� ��������� ��� ���2� ��������� ��� �� Macromolecule
not a biopolymer
Nucleic
of
Ethyne
polymer of ethylene
Phthalic acid
a synthetic polymer
homopolymer is
Bakelite
copolymer.
PAN
linear polymer
Identify the monomer in the following polymeric structures.
polymeric structure
and hexamethylene diamine
The monomers of the given polymeric structure are
does not contain
.T ����� 9j� ��� ��������� ��� ���2� ��������� ��� �� Macromolecule (C) Both (A) and
not a biopolymer ? "����< (C) Cellulose
(C) Styrene
ethylene glycol
(C) Salicylic
a synthetic polymer ?
(C) Protein
is
(C) Glyptal
(C) Polythene
polymer ?
(B) Bakelite
(D) Melamine
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structure
are
contain repeating
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(C) Both (A) and
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Styrene
glycol and
Salicylic acid
Protein
Glyptal
Polythene
Bakelite
Melamine-formaldehyde
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are decanoic
.
repeating structural units
(C) Both (A) and (B) (D) None
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(D) Neoprene.
(D) Isoprene
(D) Terephthalic
(D) Polystyrene
(D) Dacron
(D) PTFE
formaldehyde
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decanoic acid
structural units
(D) None of the
Neoprene.
Isoprene
Terephthalic
Polystyrene.
Dacron
PTFE
formaldehyde polymer.
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acid
structural units is called a
above
Terephthalic acid.
a
(9) A copolymer of acrylonitrile and 1, 3-butadine is called.
(A) Buna-N (B) Polystyrene (C) Neoprene (D) Buna-S.
(10) Which of the following is an addition (chain growth) polymer?
(A) Nylon-66 (B) Polyester (C) PVC (D) Glyptal
(11) Which of the following is not an addition polymer?
(A) Polystyrene (B) PVC (C) Polypropylene (D) Nylon
(12) An example of addition copolymer is
(A) Polythene (B) Butyl rubber (C) Neoprene (D) Natural rubber
(13) Which of the following is an addition homopolymer?
(A) polythene (B) Teflon (C) PVC (D) All the three above
(14) Which of the following is not a condensation (step growth) polymer?
(A) Melamine-formaldehyde resin (B) Bakelite
(C) Polythene (D) Polyester
(15) An example of a condensation homopolymer is
(A) Bakelite (B) Melamine-formaldehyde resin
(C) Alkyd resin (D) perlon or Nylon-6
(16) Low density polythene is prepared by
(A) Free radical polymerization (B) Cationic polymerization
(C) Anionic polymerization (D) Zeigler-Natta polymerization
(17) Natural silk is a
(A) Polypeptide (B) polysaccharide (C) polychloropene (D) polyacrylonitrile
(18) artificial silk is a
(A) Polypeptide (B) polysaccharide (C) polythene (D) Polyvinyl Chloride
(19) Among the following polymer, the strongest intermolecular forces of attraction are present in
(A) Elastomers (B) Fibres
(C) Thermoplastics (D) Thermosetting polymers
(20) Thermoplastics are
(A) Linear polymers
(B) Soften or melt on heating
(C) Molten polymer can be moulded in desired shape
(D) All the correct
(21) The polymer used in manufacture of electrical goods such as switches ,plugs etc. is
(A) Polythene (B) Bakelite (C) Melamine-formaldehyde resin (D) Neoprene
(22) The polymer used for coating electrical wires, cables etc. is
(A) Natural rubber (B) Neoprene (C) Nitrile rubber (D) PVC
(23) Which is a protein?
(A) Nylon (B) Rayon (C) Natural silk (D) Terylene
(24) Buna-S is obtained by the copolymerisation of butadiene and (A)chloroprene (B) styrene (C) acrylonitrile (D) adipic acid