Question

Assertion-Natural rubber is a polymer of cis-isoprene.
Reason-Poly Trans isoprene is called Gutta percha.
A. The assertion and the Reason are correct and the Reason is the correct explanation of the Assertion.
B. Both Assertion and the Reason are correct but the Reason is not the correct explanation of the Assertion.
C. Assertion is correct but the Reason is incorrect.
D. Both assertion and reason are incorrect.

Answer 1

Hint: we must remember that the polyisoprene is the general name for polymers obtained by polymerizing isoprene. In principle, four different isomers can be formed. Natural rubber is a linear polymer of $1,4 - addition$ polymer of $2 - methyl - 1,3 - butadiene$ $2 - methyl$.The cis-polyisoprene molecules held together by weak van der Waal interactions.

Complete step by step answer:
First of all let’s learn about some properties of natural rubber and Gutta percha.
We have to remember that the natural rubber has both elastomeric and thermoplastic properties. After vulcanizing rubber, it is a thermosetting substance. Polyisoprene is the general name for polymers obtained by polymerizing isoprene. In principle, four different isomers can be formed.
$Cis - 1,3 - polyisoprene$, also called isoprene rubber, is the main component of natural rubber.
$Trans - 1,4 - polyisoprene$ is the main component of gutta-percha.
Isoprene rubber is made by polymerization of isoprene. Polymerization was carried out in solution with anionic catalyst and Ziegler-Natta.
The product consists of at most $98$ percent and is in other $Trans - 1,4 - polyisoprene$ respects as unusual as natural rubber. As a result, it does not crystallize as easily as natural ingredients and is not as strong or sticky in its raw state (not vulcanized). However, if not, isoprene rubber is a complete substitute for natural rubber. These two materials are mainly used for tires, although they are also preferred for rubber springs and attachments because of their good fatigue resistance and high durability.
 $Trans - 1,4 - polyisoprene$ can also be synthesized with Ziegler-Natta catalysts to produce synthetic weights with similar properties that are also used in golf ball coatings as well as orthopaedic devices such as splints and braces.
So, from the above points it’s clear that both assertion and reason is correct.

Hence, correct option is (B) Assertion and reason both are correct but reason is not the correct explanation of assertion.

Note: We must remember that the percentage of polyisoprene repeating units containing each type of polymer bond depends on the reaction mechanism.
In contrast to the $Cis - 1,3 - polyisoprene$ , the $Trans - 1,4 - polyisoprene$ is highly crystalline, so balls and gutta-percha are tough, hard and coarse materials - properties that led to their use as bowls in the ${19^{th}}$ century, Underwater cables and golf balls.