Problem 24 - 43 Years JEE ADVANCED (1978-2020) + JEE MAIN Chapterwise & Topicwise Solved Papers Chemistry

Question

Choose the correct option(s) from the following. [Adv. 2019] (a) Nylon-6 has amide linkages (b) Cellulose has only \(\square-D\)-glucose units that are joined by glycosidic linkages (c) Teflon is prepared by heating tetrafluoroethene in presence of a persulphate catalyst at high pressure (d) Natural rubber is polvisoprene containing trans alkene unito

Step-by-Step Solution

Answer

Correct options are (a) and (c).

Step 1: Analyze Nylon-6 Composition

Nylon-6 is a type of polymer known as a polyamide. It is produced by the polymerization of caprolactam, which contains amide linkages. Therefore, statement (a) is correct because Nylon-6 indeed has amide linkages.

Step 2: Examine Cellulose Structure

Cellulose is a polysaccharide composed of \beta-D-glucose units. These glucose units are linked together by β-1,4-glycosidic bonds. Since the question states \( \alpha-D \)-glucose, which is incorrect for cellulose, statement (b) is not correct.

Step 3: Verify Teflon Preparation

Teflon, also known as PTFE (polytetrafluoroethylene), is a polymer constructed from tetrafluoroethylene monomers. It is synthesized through a polymerization reaction involving a free radical initiator, often using a persulphate catalyst under high pressure conditions. Thus, statement (c) is correct.

Step 4: Investigate Natural Rubber Structure

Natural rubber is primarily composed of polyisoprene. It features cis-1,4-polyisoprene rather than trans configurations. Therefore, statement (d) is incorrect because it wrongly states that natural rubber contains trans alkene units.

Key Concepts

Nylon-6

Nylon-6 is a synthetic polymer that falls under the category of a polyamide. It is distinctively created through the polymerization process of caprolactam. This process involves a ring-opening polymerization where the caprolactam ring is broken to form a long chain, resulting in the Nylon-6 polymer. One of the fundamental characteristics of Nylon-6 is the presence of amide linkages in its backbone. These amide linkages, or peptide bonds, are responsible for the strength and elasticity of the material.

Some notable properties of Nylon-6 include:

• High tensile strength
• Resistance to abrasion
• High melting point
• Good resistance to chemicals and oils

Due to its strength and durability, Nylon-6 is often used in textiles, automotive parts, and mechanical components. It illustrates an excellent example of how human-made polymers can closely mimic some of the properties found in natural fibers, like wool and silk.

Cellulose

Cellulose is a naturally occurring polymer found in the cell walls of plants. Comprising a significant portion of plant biomass, cellulose is known for its robust structure and high tensile strength, which are essential for maintaining the plant cell's shape. It is made up of long chains of \(\beta\)-D-glucose molecules, specifically linked by \(\beta\)-1,4-glycosidic bonds. These bonds create a highly stable and linear structure.

Key points about cellulose are:

• It is not soluble in water due to its crystalline structure.
• It exhibits resistance to microbial degradation.
• It is utilized in producing paper, textiles, and as a food additive.

Cellulose is essential for many everyday products, and its ability to form hydrogen bonds between hydroxyl groups leads to the tightly packed crystalline fiber, greatly contributing to its mechanical properties. This incredible polymer is a testament to the amazing structures that nature produces.

Teflon

Teflon, scientifically known as polytetrafluoroethylene (PTFE), is a high-performance polymer that is best known for its non-stick properties. The manufacturing of Teflon involves the polymerization of tetrafluoroethylene monomers. This process often employs a free radical initiator in the presence of a persulphate catalyst under high pressure conditions.

The unique properties of Teflon include:

• Exceptional non-stick properties, making it ideal for cookware coatings.
• Resistance to chemical reactions.
• High thermal stability and low friction.
• Insulating properties, useful in high temperature and hazardous chemical environments.

These features make Teflon an essential material in various industrial applications, from non-stick cookware to wiring insulation and sealing materials in chemical industries. Understanding its composition and synthesis process showcases the innovative approaches in modern polymer chemistry.

Natural Rubber

Natural rubber is a naturally occurring polymer primarily composed of cis-1,4-polyisoprene. This substance is derived from the latex of rubber trees, giving it an elastic, flexible quality that makes it invaluable in manufacturing. The polyisoprene in natural rubber is arranged in a cis configuration, an orientation that contributes significantly to its rubbery properties.

Important features of natural rubber are:

• High elasticity and resilience.
• Good tensile strength and extensive elongation capacity.
• Excellent bounce and shock absorption qualities.
• Vulnerable to degradation in the presence of ozone, ultraviolet light, and oil.

These attributes make natural rubber ideal for use in tires, elastic bands, and various shock-absorbing goods. It's a remarkable example of nature's capability to produce materials that possess a perfect balance of strength and flexibility, useful across numerous industries.