Q18 / 90 · JEE Main 2022 (28 Jun Shift 2) · Chemistry
Given below are two statements, one is Assertion and other is Reason.
Assertion: Natural rubber is a linear polymer of isoprene called cis-polyisoprene with elastic properties.
Reason: The cis-polyisoprene molecules consist of various chains held together by strong polar interactions with coiled structure.
In the light of the above statements, choose the correct one from the options given below
Given below are two statements, one is Assertion and other is Reason.
Assertion: Natural rubber is a linear polymer of isoprene called cis-polyisoprene with elastic properties.
Reason: The cis-polyisoprene molecules consist of various chains held together by strong polar interactions with coiled structure.
In the light of the above statements, choose the correct one from the options given below
- AA Both Assertion and Reason are true and Reason is the correct explanation of Assertion
- BBoth Assertion and Reason are true but Reason is not the correct explanation of Assertion.
- Correct answerCAssertion is true but Reason is false.
- DAssertion is false but Reason is true.
Solution
Natural rubber
Natural rubber is a polymer of isoprene, and obtained from natural source-latex tree. In natural rubber, isoprene units are joined together in head-to-tail fashion and all double bonds in the polymer chain have cis configurations as shown in the given figure.
The polymer contains cis repeating units and has a molecular weight ranging from upto
The cis arrangement of the double bonds in natural rubber prevents the rubber molecules from fitting into an ordered structure. Thus, rubber is an amorphous polymer. Because of the random coiling of its polymer chains, rubber stretches easily. When stretched, the rubber molecules are forced into a higher energy state. when the tension is released, rubber snaps back to its original random coiled state but it is nonpolar therefore statement-II is incorrect.
Hence, the correct answer is option: 'C'.