Q.75 Chemistry ⭐ 360° Option Elimination Active

Vault ↗

NEET 2021 Chemistry Question 75 Solution

Topic: Polymers · Official NTA Booklet Code M1

Question

Which one of the following polymers is prepared by addition polymerisation?

(1)Teflon
(2)Nylon-66
(3)Novolac
(4)Dacron

✓

Verified Against NTA Final Answer Key

Option (1) : Teflon

📚 Polymers Easy

📋 Given Parameters & Problem Setup

Polymerisation Mechanism Addition polymerisation (chain growth)

⚡

The 30-Second Exam Hall Shortcut: ⚡ Monomer with C=C Double Bond = Addition Polymer!

⏱️ Save ~20 seconds

Addition polymers form by repeated addition of unsaturated monomers containing double bonds without elimination of small molecules. Teflon (polytetrafluoroethene) is prepared from tetrafluoroethene ( $CF_2=CF_2$ ). Nylon-66, Novolac, and Dacron are all CONDENSATION polymers involving loss of $H_2O$ ! Match Option (1)!

1 Addition polymer: Formed from monomers with double/triple bonds with no byproduct.

2 Check Teflon:

n CF_2=CF_2 \xrightarrow{\text{catalyst}} -[CF_2-CF_2]_n-

\implies

Pure addition polymer.

3 Check Nylon-66: Hexamethylenediamine + adipic acid

\to

Condensation polymer (eliminates

H_2O

4 Check Novolac: Phenol + formaldehyde

\to

Condensation polymer (eliminates

H_2O

5 Check Dacron (Terylene): Ethylene glycol + terephthalic acid

\to

Condensation polymer (eliminates

H_2O

6 Match Option (1) Teflon.

🛡️

Why You Can 100% Trust This Shortcut: Canonical NCERT Polymers classification based on mode of polymerisation.

📐

Step-by-Step Rigorous Workflow & Mathematical Proof

Step 1

Definition of Addition Polymerisation

Addition (chain-growth) polymerisation involves repeated addition of monomer molecules possessing double or triple bonds to a growing polymer chain, usually in the presence of free-radical initiators, without the elimination of any small molecular byproducts like water, alcohol, or ammonia.

Step 2

Preparation and Reaction of Teflon (Polytetrafluoroethene)

Teflon is manufactured by heating tetrafluoroethene with a free radical or persulphate catalyst at high pressures:

n\,\text{CF}_2=\text{CF}_2 \xrightarrow[\text{High pressure}]{\text{Persulphate catalyst}} -[\text{CF}_2-\text{CF}_2]_n- \quad (\mathbf{\text{Addition Polymer}})

Step 3

Analysis of Condensation Polymers

- Nylon-66: Formed by condensation of hexamethylenediamine and adipic acid with elimination of $H_2O$ (polyamide condensation polymer). - Novolac: Linear condensation product of phenol and formaldehyde with loss of $H_2O$ . - Dacron (Terylene): Formed by condensation of ethylene glycol and terephthalic acid with elimination of $H_2O$ (polyester condensation polymer).

⭐

360° Option Elimination Engine Key Feature

Diagnose every choice: Know exactly why the right option works and why distractors fail.

4-Option Deep Scan

1 1

✓ 100% Correct

Verdict & Scientific Reason:

Formed strictly by addition polymerisation of tetrafluoroethene ( $CF_2=CF_2$ ).

💡

Why this is airtight: None; textbook polymer classification.

2 2

✗ Incorrect

Verdict & Scientific Reason:

Condensation polyamide polymer eliminating water molecules.

⚠️

Student Fallacy (Why candidates pick this trap): Confusing step-growth condensation with chain-growth addition.

3 3

✗ Incorrect

Verdict & Scientific Reason:

Condensation polymer formed from phenol and formaldehyde.

⚠️

Student Fallacy (Why candidates pick this trap): Misclassifying phenol-formaldehyde resins.

4 4

✗ Incorrect

Verdict & Scientific Reason:

Condensation polyester polymer eliminating water.

⚠️

Student Fallacy (Why candidates pick this trap): Confusing polyester condensation with addition.

⚠️

NTA Trap Alert: Polyamide/Polyester Condensation vs. Addition Trap

Students frequently mix up Nylon-66 and Dacron with addition polymers because they are common synthetic fibers. Nylon-66 and Dacron are both classic CONDENSATION polymers (step-growth). Teflon is an ADDITION polymer.

🛡️ How to avoid the -1 mark: Identify the monomer:

CF_2=CF_2

has a

C=C

double bond

\implies

Addition polymer.

📖

Core NEET Syllabus Standard

NCERT Chemistry · Polymers Standard Benchmark

Core Scientific Principle Tested:

"Teflon is manufactured by addition polymerisation of tetrafluoroethene with a free radical catalyst under high pressure."

Syllabus Focus: Addition Polymers (Polytetrafluoroethene / Teflon)

✓ Core NEET UG Syllabus Anchor Syllabus & Academic Standards ↗

Ready to attempt under real exam pressure?

Test your speed and accuracy in the authentic 200-minute timed NTA simulator.

Launch NEET 2021 CBT Test →

← Previous (Q.74) All Chemistry Questions Grid Next (Q.76) →

Spotted a mistake in this solution? Report an error (support@mycompetitiveexams.com)

⚖️ Legal & Fair Dealing Notice: Sourced from publicly released NEET 2021 question papers and NEET answer keys for private study, research, and non-commercial educational practice under Fair Dealing (Section 52(1)(a) of the Indian Copyright Act, 1957). Not affiliated with or endorsed by NTA or NMC.

NEET 2021 Chemistry Question 75 Solution

Question

The 30-Second Exam Hall Shortcut: ⚡ Monomer with C=C Double Bond = Addition Polymer!

Step-by-Step Rigorous Workflow & Mathematical Proof

Definition of Addition Polymerisation

Preparation and Reaction of Teflon (Polytetrafluoroethene)

Analysis of Condensation Polymers

360° Option Elimination Engine Key Feature

NTA Trap Alert: Polyamide/Polyester Condensation vs. Addition Trap

Core NEET Syllabus Standard

Ready to attempt under real exam pressure?

🔗 Related Questions — Polymers

Free Radical Polymerization of Chloroprene to Form Neoprene

Natural vs Synthetic Polymers: Natural Rubber as cis-1,4-Polyisoprene

Solve 4 NEET Questions a Day — One per Subject