Which of the following is the monomer of natural rubber?

Isoprene

The correct answer is option 2. Isoprene.

Natural rubber, also known as polyisoprene, is a polymer composed of repeating units of the monomer isoprene. Isoprene is a simple hydrocarbon molecule with the chemical formula C5H8. It consists of five carbon atoms arranged in a chain with two double bonds between the carbon atoms:

\(\text{CH}_2 = \text{C}(\text{CH}_3) - \text{CH} = \text{CH}_2\)

The presence of these conjugated double bonds makes isoprene highly reactive. When subjected to appropriate conditions, such as heat, pressure, or the presence of catalysts, isoprene molecules can undergo polymerization, where multiple isoprene units join together to form long chains.

The polymerization process involves the addition of isoprene monomers, where the double bonds in the monomer molecules open up and link with neighboring monomers, forming a chain-like structure. This process repeats, with more and more monomers joining the growing polymer chain, until a long chain of repeating isoprene units is formed.

The resulting polymer is natural rubber, which consists of long chains of polyisoprene molecules. Natural rubber exhibits unique properties such as elasticity, flexibility, and resilience, making it ideal for various applications, including tire production, conveyor belts, hoses, seals, and many other industrial and consumer products.

In summary, the monomer of natural rubber is isoprene, and natural rubber is formed through the polymerization of isoprene molecules to create long chains of polyisoprene, which give natural rubber its characteristic properties.