Which of the following polymers involve cross linkages?
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → Bakelite
Phenol and formaldehyde first give a linear product, novolac. On heating with more formaldehyde, the –\( \ce{CH2} \)– groups also join the chains to one another, giving a cross-linked, infusible thermosetting polymer, bakelite.
Why the other options are incorrect
Option (2) PVC — Incorrect. A linear thermoplastic; there are no bonds between the chains.
Option (3) Nylon 6 — Incorrect. A linear polyamide fibre; its chains are held by hydrogen bonds, not cross-linked.
Option (4) Novolac — Incorrect. The linear product formed before cross-linking.
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):
Phenol-Formaldehyde Polymer – …
