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25
Subjective

Identify the polymer given below.

Explanation

The given polymer is formed by', 1, 4--addition of 2- methylbuta- 1,3- diene (isoprene) and stereochemistry is 'cis' throughout. Therefore, the given polymer is 'cis'- polyisoprene i.e., natural rubber.

26
Subjective

Why are rubber called elastomers?

Explanation

They change their shape on applying force and regain their original shape on removal of the applied force. Hence, rubbers are called elastomers.

27
Subjective

Can enzyme be called a polymer?

Explanation

Yes, these are made up of proteins which are polymers of amino acids.

28
Subjective

Can nucleic acid, protein and starch be considered as step growth polymers?

Explanation

Yes, nucleic acid, protein and starch can be considered as step growth polymers as during their polymerisation reaction, they lead to removal of water molecule or any neutral molecule also. Thus, these are the examples of condensation polymers or step growth polymerisation.

29
Subjective

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

Explanation

Reaction between melamine and formaldehyde can be shown as

Melamine-formaldehyde polymer is formed by this monomer unit.