Which one of the following statements is not true? a)Buna S is a copol...
Natural rubber is cis-configuration of 1,4-polyisoprene or
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Which one of the following statements is not true? a)Buna S is a copol...
Explanation:
Natural rubber is a polymer of isoprene, not butadiene.
Here is an explanation of each statement:
a) Buna S is a copolymer of butadiene and styrene:
Buna S is a synthetic rubber that is a copolymer of butadiene and styrene. It is formed by the polymerization of these two monomers. This statement is true.
b) Natural rubber is a 1,4 polymer of isoprene:
Natural rubber is a polymer of isoprene. Isoprene is a monomer with a molecular formula of C5H8. In the polymerization process, isoprene molecules combine with each other in a 1,4 fashion, meaning that one carbon atom from each monomer is linked to the fourth carbon atom of the adjacent monomer. This statement is true.
c) In vulcanization, the formation of sulfur bridges between different chains makes rubber harder and stronger:
Vulcanization is a chemical process that involves the addition of sulfur to rubber. During vulcanization, sulfur bridges are formed between the polymer chains, which crosslink them and make the rubber harder, stronger, and more durable. This statement is true.
d) Natural rubber has the trans-configuration at every double bond:
This statement is not true. Natural rubber has a cis-configuration at every double bond. In the cis-configuration, the substituent groups are on the same side of the double bond, whereas in the trans-configuration, the substituent groups are on opposite sides of the double bond. The presence of the cis-configuration gives natural rubber its unique properties, such as high elasticity and flexibility.
In summary, the statement that is not true is option 'D'. Natural rubber has the cis-configuration at every double bond, not the trans-configuration.