Question

Natural rubber or raw rubber consists of basic material latex which is a dispersion of isoprene. During the treatment, this isoprene forms a high molecular weight polymer of isoprene. Natural rubber can be obtained from five hundred different species of plants.
In the isoprene polymer all the isoprene units have which of the following:
A.Trans 1, 4 configuration
B.Cis 1, 4 configuration
C.Both cis and trans 1, 4 configuration
D.None of these

Answer 1

Hint: Natural rubber is an additional polymer of a substance which is an unsaturated hydrocarbon obtained generally in processing petroleum or coal tar.

Complete step by step answer:
Natural rubber is the cis-isomer of poly-isoprene and is formed from isoprene.Its IUPAC name is 2-methyl-1,3-butadiene.
The monomer of natural rubber is Isoprene. Poly-isoprene is a polymer of isoprene $({{C}_{5}}{{H}_{8}})$ that is the primary chemical constituent of natural rubber. Many properties of rubber make it a very useful compound like Specific gravity, Abrasion resistance, Tear resistance, Compression set, Resilience, Elongation, Tensile modulus, Tensile strength.
Hence, the correct answer is cis-2-methyl-1,3-butadiene or isoprene which is option B.

Note:
To convert raw rubber into tough and useful product vulcanization of rubber is done. Sulphur is added to polymer and heated. This makes sulphur atoms cross link the adjacent polymer chains.
This cross linking improves following properties of rubber:
-A tougher material that is more resistant to oxidation
-More elastic material as cross linked chains can revert back to their positions
-It becomes more heat resistant
-And less soluble in organic solvents.