Question

What is ‘Cis-1,4-polyisoprene’?
(A) Thermoplastic
(B) Thermosetting plastic
(C) Elastic (rubber)
(D) Resin

Answer 1

Hint: Cis-1,4-polyisoprene is a polymer which is formed by the combination of a large number of isoprenes (2-methyl-1,3-butadiene). It is an addition polymer.

Complete Step by Step Solution:
Isoprene is an unsaturated compound containing two double bonds. The large number of isoprenes combines to form cis-1,4-polyisoprene. The structure of cis-1,4 polyisoprene is shown as

The isoprene units in cis-1,4-polyisoprene are joined together by weak Vander Waal forces. This is the reason that it is elastic in nature. Natural rubber is cis-1,4-polyisoprene. Natural rubber is a linear, unsaturated long chain of aliphatic hydrocarbons. The properties of natural rubber are that it is very soft and elastic.
Correct Option: (C) Elastic (rubber).

Additional Information: The cis-1,4-polyisoprene mainly occurs as natural rubber in the latex of many plants and trees. Ziegler-Natta polymerization can be used to create polyisoprene. A natural rubber ranges from soft erasers to ebonite. When the bark of tropical and subtropical trees is broken, a milky white liquid called latex drips down. That is what constitutes natural rubber. Rubber can be used in tyres, seats, and airbags of cars. It can also be used as an expandable garment in the clothing industry, such as gym and cycling shorts.

Note: The other options Thermoplastic and thermosetting plastic are the types of polymers classified on the basis of molecular forces. Thermoplastics have weak van der waal forces, e.g.- polythene. whereas thermosetting plastic has intermolecular forces, e.g.- Bakelite. Resin is a hard, brittle substance obtained from plants and can be used as paints, adhesives, and inks.