Monomers of terylene are:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → HOH2C–CH2OH and HOOC–C6H4–COOH
Terylene (Dacron) is a polyester, a condensation polymer of a diol and a dicarboxylic acid. It is made by heating ethylene glycol (ethane-1,2-diol) with terephthalic acid (benzene-1,4-dicarboxylic acid); every ester link formed releases a molecule of water:
\( n\,\ce{HOCH2CH2OH} + n\,\ce{HOOC-C6H4-COOH} \rightarrow \ce{[-OCH2CH2O-CO-C6H4-CO-]}_{n} + 2n\,\ce{H2O} \)
Why the other options are incorrect
Option (1) adipic acid and hexamethylenediamine — Incorrect. These are the monomers of nylon 6,6, a polyamide.
Option (2) phenol and formaldehyde — Incorrect. These are the monomers of Bakelite, a phenol-formaldehyde resin.
Option (4) buta-1,3-diene and acrylonitrile — Incorrect. These are the monomers of Buna-N rubber, an addition copolymer.
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):
Polyesters
