Problem 26 - 43 Years JEE ADVANCED (1978-2020) + JEE MAIN Chapterwise & Topicwise Solved Papers Chemistry

Question

The correct match between Item-I and Item - II is: [Main Sep. 06, 2020 (II)] Item - I \(\quad\) Item - II (a) Natural rubber (I) 1,3 -butadiene \(+\) styrene (b) Neoprene (II) 1, 3-butadiene \(+\) acrylonitrile (c) Buna-N (III) Chloroprene (d) Buna-S (IV) Isoprene(a) \((\mathrm{A})-(\mathrm{III}),(\mathrm{B})-(\mathrm{IV}),(\mathrm{C})-(\mathrm{I}),(\mathrm{D})-(\mathrm{II})\) (b) \((\mathrm{A})-(\mathrm{III}),(\mathrm{B})-(\mathrm{IV}),(\mathrm{C})-(\mathrm{II}),(\mathrm{D})-(\mathrm{I})\) (c) \((\mathrm{A})-(\mathrm{IV}),(\mathrm{B})-(\mathrm{IIl}),(\mathrm{C})-(\mathrm{II}),(\mathrm{D})-(\mathrm{I})\) (d) \((\mathrm{A})-(\mathrm{IV}),(\mathrm{B})-(\mathrm{IIl}),(\mathrm{C})-(\mathrm{I}),(\mathrm{D})-(\mathrm{II})\)

Step-by-Step Solution

Answer

Correct option is (c): \((\mathrm{A})-(\mathrm{IV}), (\mathrm{B})-(\mathrm{III}), (\mathrm{C})-(\mathrm{II}), (\mathrm{D})-(\mathrm{I})\).

Step 1: Identify Components in Item-I

Let's first recall what each component in Item-I is generally made from. 1. Natural rubber is derived from isoprene. 2. Neoprene is made from chloroprene. 3. Buna-N is a copolymer of 1,3-butadiene and acrylonitrile. 4. Buna-S is a copolymer of 1,3-butadiene and styrene.

Step 2: Match Components from Item-I to Item-II

Now we will match the components from Item-I with those in Item-II. - Natural rubber (a) corresponds to Isoprene (IV) because natural rubber is made from the polymerization of isoprene monomers. - Neoprene (b) corresponds to Chloroprene (III) as neoprene is manufactured using chloroprene. - Buna-N (c) matches with 1,3-butadiene + acrylonitrile (II) since Buna-N is a copolymer of these monomers. - Buna-S (d) corresponds to 1,3-butadiene + styrene (I) as it is made from these two monomers.

Step 3: Find the Given Matching Option

Now, check each given option to see which matches our findings:Option (a): \((\mathrm{A})-(\mathrm{III}), (\mathrm{B})-(\mathrm{IV}), (\mathrm{C})-(\mathrm{I}), (\mathrm{D})-(\mathrm{II}) \)Option (b): \((\mathrm{A})-(\mathrm{III}), (\mathrm{B})-(\mathrm{IV}), (\mathrm{C})-(\mathrm{II}), (\mathrm{D})-(\mathrm{I}) \)Option (c): \((\mathrm{A})-(\mathrm{IV}), (\mathrm{B})-(\mathrm{IIl}), (\mathrm{C})-(\mathrm{II}), (\mathrm{D})-(\mathrm{I}) \)Option (d): \((\mathrm{A})-(\mathrm{IV}), (\mathrm{B})-(\mathrm{IIl}), (\mathrm{C})-(\mathrm{I}), (\mathrm{D})-(\mathrm{II}) \)From our matches, option (c) is correct as:\( (\mathrm{A})-(\mathrm{IV}),\ (\mathrm{B})-(\mathrm{IIl}),\ (\mathrm{C})-(\mathrm{II}),\ (\mathrm{D})-(\mathrm{I}) \)

Key Concepts

Natural Rubber

Natural rubber is a fascinating natural polymer, derived from the latex of rubber trees, primarily species like Hevea brasiliensis. The key component of natural rubber is polyisoprene, which consists predominantly of the cis-1,4-polyisoprene polymer. This form of polymer gives natural rubber its elastic and resilient properties, which are essential for products like tires, gloves, and many other everyday items.

Natural rubber is revered for its ability to "bounce back" or return to its original shape and size after being stretched or compressed. This elasticity is due to the long, coiled chain structure of the isoprene units, which can stretch and contract without breaking. However, natural rubber does have some limitations, such as sensitivity to temperature changes and susceptibility to ozone and UV degradation. To improve its properties, it is often vulcanized—a process that involves heating with sulfur to create cross-links between polymer chains—making the rubber stronger and more durable.

Neoprene

Neoprene, also known as polychloroprene, is a synthetic rubber that is produced by polymerizing chloroprene. This synthetic rubber has a series of notable properties that distinguish it from natural rubber. One of its primary benefits is resistance to degradation from sunlight, ozone, and weather conditions, making it highly durable in challenging environments.

Neoprene is also resistant to oils and many chemicals, which allows it to be used in various industrial applications, such as protective gear, wetsuits, and gaskets. Its fire retardant properties further enhance its suitability for tough applications. Neoprene is also valued for its thermal insulation and flexibility over a wide temperature range, which makes it a preferred choice in a wide array of contexts, from sports equipment to medical equipment.

Buna-N

Buna-N, also known as Nitrile rubber or NBR, is a synthetic copolymer made from 1,3-butadiene and acrylonitrile. This type of rubber is particularly prized for its excellent resistance to oils, fuels, and other chemicals, which is why it's commonly used in the automotive and aeronautical industry for gaskets and seals. It serves as a perfect material where oil resistance and resilience are critical features.

The proportion of acrylonitrile in the copolymer can be varied to enhance certain properties. For example, increasing the acrylonitrile content improves the oil resistance and mechanical strength but may decrease the rubber's flexibility at low temperatures. Conversely, lower acrylonitrile content provides better flexibility but less resistance to oils. Such versatility makes Buna-N a popular choice across different applications requiring specific performance characteristics.

Buna-S

Buna-S, also known as Styrene-Butadiene Rubber (SBR), is another synthetic rubber that finds extensive use in a variety of industries. It is formed by co-polymerizing 1,3-butadiene with styrene. This type of rubber offers good abrasion resistance and aging stability, although not as resilient to oils as Buna-N.

One of Buna-S's key applications is in the tire industry, where it is used to enhance the wear resistance and lifespan of tires. It's also used in other rubber products such as conveyor belts, shoe soles, and hose linings. Due to its balanced properties of resilience, toughness, and wear resistance, Buna-S is favored for products that encounter regular wear and tear.

The inclusion of styrene in the polymer composition contributes to the rigidity and resilience of Buna-S, while the butadiene content provides the elastic properties. This balance creates a flexible yet durable rubber that serves well across various temperature ranges and environmental conditions.