Q.59 Chemistry ⭐ 360° Option Elimination Active
NEET 2023 Chemistry Question 59 Solution
Topic: Polymers · Official NTA Booklet Code G5
Question
Which amongst the following molecules on polymerization produces neoprene?
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Verified Against NTA Final Answer Key
Option (3) : H₂C = C(Cl) – CH = CH₂ (Chloroprene)
📚 Polymers Easy
📋 Given Parameters & Problem Setup
Target polymer Neoprene (Polychloroprene)
Monomer class Conjugated diene derivative
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⏱️ Save ~25 seconds The 30-Second Exam Hall Shortcut: ⚡ Rubber Monomer Match Hack: Neo = Chloro!
Natural rubber is polyisoprene (methyl group at C-2). Synthetic Neoprene is polychloroprene (chlorine atom at C-2: H₂C = C(Cl)–CH = CH₂). Instant Option (3) in 5 seconds!
1 Recall common conjugated diene monomers:
2 - Isoprene: H₂C = C(CH₃)–CH = CH₂ ⟶ Natural rubber (cis-1,4-polyisoprene).
3 - 1,3-Butadiene: H₂C = CH–CH = CH₂ ⟶ Buna-S / Buna-N copolymer component.
4 - Chloroprene: H₂C = C(Cl)–CH = CH₂ ⟶ Neoprene (synthetic rubber).
5 Match the structure of chloroprene: 2-chlorobuta-1,3-diene, which is Option (3).
6 Select Option (3) directly!
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Why You Can 100% Trust This Shortcut: Polymer Chemistry · Monomers of Synthetic Rubbers (Neoprene is commercially prepared by the free radical polymerization of chloroprene, 2-chlorobuta-1,3-diene).
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Step-by-Step Rigorous Workflow & Mathematical Proof
Step 1
Identification of Neoprene
Neoprene (polychloroprene) is a synthetic elastomer with superior resistance to vegetable and mineral oils. It is synthesized by the addition polymerization of its monomer in the presence of oxygen or peroxide catalysts:
Step 2
IUPAC and Common Nomenclature of the Monomer
The monomer shown in Option (3) is 2-chlorobuta-1,3-diene, commonly known as chloroprene:
Step 3
Contrast with Other Diene Monomers
Differentiating the structures of the dienes provided in the options:
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4-Option Deep Scan
360° Option Elimination Engine Key Feature
Diagnose every choice: Know exactly why the right option works and why distractors fail.
1 (1)
✗ Incorrect Verdict & Scientific Reason:
Isoprene: monomer of natural rubber, not neoprene.
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Student Fallacy (Why candidates pick this trap): Candidate confused isoprene with chloroprene.
2 (2)
✗ Incorrect Verdict & Scientific Reason:
1,3-Butadiene: monomer of polybutadiene and Buna rubbers.
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Student Fallacy (Why candidates pick this trap): Candidate selected unsubstituted butadiene.
3 (3)
✓ 100% Correct Verdict & Scientific Reason:
Chloroprene (2-chlorobuta-1,3-diene): monomer of neoprene.
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Why this is airtight: None. Candidate knew the structure of chloroprene.
4 (4)
✗ Incorrect Verdict & Scientific Reason:
Vinylacetylene: raw material used in synthesis of chloroprene, not the monomer itself.
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Student Fallacy (Why candidates pick this trap): Candidate confused the industrial precursor with the actual polymerization monomer.
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NTA Trap Alert: Confusing Isoprene (Natural Rubber) with Chloroprene (Neoprene)
Isoprene has a -CH₃ group at C-2, forming natural rubber. Chloroprene has a -Cl group at C-2, forming neoprene. Mixing up -CH₃ and -Cl leads directly to picking Option (1).
🛡️ How to avoid the -1 mark: Memory Hook: "Chloro-prene makes Neo-prene" (both end in -prene, and chloro matches neoprene).
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Core NEET Syllabus Standard
National Eligibility cum Entrance Test (NEET UG) · Polymers Standard Benchmark
Core Scientific Principle Tested:
"Neoprene is formed by the free radical polymerization of chloroprene (2-chlorobuta-1,3-diene)."
Syllabus Focus: Synthetic Rubbers – Neoprene
Preserved in Rationalized Curriculum Syllabus & Academic Standards ↗
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