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Example-1

Example-1
Which of the following is a syndiotactic polymer in Description: 49512.png?
  1. All Y groups lie on one side of the chain and all Z groups on the other side
  2. The Y and Z groups lie alternately on each side of the chain
  3. The Y and Z groups are arranged in a random fashion
  4. Y and Z groups are same
Solution (B)
Three stereochemical arrangements are possible:
  1. Isotactic (same order): Here groups are arranged on one side of the chain. All Y groups lie on one side and all Z groups on the opposite side of the chain.
     
  2. Syndiotactic (alternating order): The Y and Z groups lie alternately on each side of the chain.
     
  3. Atactic (random order): The Y and Z groups are arranged in a random fashion.
     

Example-2

Example-2
The degree of crystallinity of which of the following is highest?
  1. Atactic polyvinylchloride
  2. Isotactic polyvinylchloride
  3. Syndiotactic polyvinylchloride
  4. All of these
Solution (C)
Syndiotactic polyvinylchloride
 
Description: 49519.png
 
In this arrangement, the chlorine atoms are alternately arranged. The polymer is stereoregular and has high crystallinity.
 

Example-3

Example-3
The synthetic polymer which resembles natural rubber is:
  1. neoprene
  2. chloroprene
  3. glyptal
  4. nylon
Solution (A)
In neoprene, monomer unit is
Description: 49528.png (chloroprene)
 
while isoprene Description: 49535.png is the monomer of natural rubber.
 

Example-4

Example-4
Three-dimensional molecules with cross links are formed in the case of a:
  1. thermoplastic
  2. thermosetting plastic
  3. both
  4. none
Solution (B)
Thermosetting plastics have a three-dimensional cross-linked structure. Such polymers are prepared in two steps. The first step is the formation of long-chain molecules, which are capable of further reaction with each other. The second step is the application of heat, which causes a reaction to occur between the chains, thus producing a complex cross-linked polymer.
 

Example-5

Example-5
Example of condensation polymer is:
  1. Formaldehyde → meta-formaldehyde
  2. Acetaldehyde → para-aldehyde
  3. Acetone → mesityl oxide
  4. Ethene →polyethene
Solution (C)
Polymers formed by condensation process with the elimination of small molecules such as Description: 49544.png, etc., are known as condensation polymers.
 
For example,
Description: 49552.pngDescription: 49561.png
 





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