Among the following polymers, which one is the copolymer?

The correct answer is Option (4) → Glyptal

A copolymer is a polymer whose repeating units are derived from two different kinds of monomer; a homopolymer is made from a single monomer. Glyptal is a polyester made by condensation of ethylene glycol and phthalic acid, so its repeating unit comes from two different monomers:

    n \( \ce{HOH2C-CH2OH} \) + n \( \ce{C6H4(COOH)2} \) → –[OCH₂–CH₂OOC–C₆H₄–CO]_n– + 2n \( \ce{H2O} \)

Why the other options are incorrect

• Option (1) Polypropene — Incorrect. A homopolymer of a single monomer, propene (\( \ce{CH3-CH=CH2} \)).

• Option (2) Polystyrene — Incorrect. A homopolymer of a single monomer, styrene (\( \ce{C6H5-CH=CH2} \)).

• Option (3) Polyvinyl chloride — Incorrect. A homopolymer of a single monomer, vinyl chloride (\( \ce{CH2=CHCl} \)).

Note: This question is from the pre-rationalised NCERT book (2022-23). The topic is not there in the latest NCERT book (2026-27), and it is also out of the CUET 2026 syllabus.

NCERT (Pre-rationalised edition, 2022-23):
Classification Based on Mode of Polymerisation – …