Polymer structure/mechanism check: pick the wrong statement about polymer formation and properties.

Introduction / Context:
Understanding how polymer architecture forms is vital to predicting behavior in processing and service. This question asks you to identify the incorrect statement, focusing on polymerisation mechanisms and structural effects.

Given Data / Assumptions:

• Bifunctional monomers produce linear chains via step-growth or chain-growth depending on functionality.
• Crosslinking creates network structures with very different properties.
• Polyester formation route is tested.

Concept / Approach:
Polyesters are produced by condensation (step-growth) between diols and diacids/anhydrides, eliminating small molecules (e.g., water). They are not made by an addition mechanism. The other statements broadly align with polymer science: linear chains from bifunctional monomers are typically thermoplastic; crosslinking leads to elastomeric/thermoset behavior; branching and crosslinking reduce solubility and increase softening or glass transition.

Step-by-Step Solution:
Evaluate each statement against standard polymer chemistry.Identify the mechanism for polyester formation: condensation, not addition.Therefore option (d) is the wrong statement.

Verification / Alternative check:
Textbook step-growth kinetics and Carothers’ theory describe polyesters arising from diol–diacid reactions producing ester linkages plus by-products.

Why Other Options Are Wrong:
(a), (b), (c) are consistent generalisations about structure–property relations.

Common Pitfalls:
Equating “addition” with any polymerisation; forgetting that many thermoplastics (PET, nylons) are condensation polymers.

Final Answer:
Dibasic acids react with dihydric alcohols to give polyesters using an addition polymerisation reaction.