Solubility of high polymers: pick the single WRONG statement among the following general rules.

Introduction / Context:
Polymer solution behaviour differs from small molecules. Viscosity, swelling, and solubility are governed by chain entanglements, solvent–polymer interactions, and crosslinking. This question asks you to isolate an incorrect generalization.

Given Data / Assumptions:

• High polymers refer to long-chain macromolecules.
• Solubility and viscosity trends are qualitative.
• Crosslinking is considered in the context of network polymers.

Concept / Approach:
Statements (a)–(c) are broadly correct: crosslinking suppresses dissolution; “like dissolves like” applies (aliphatic vs aromatic); and higher solvent molecular weight often reduces solvent power and diffusion, lowering swelling/solubility. Statement (d) is wrong: solutions of very high-molecular-weight polymers are highly viscous even at low concentrations due to chain entanglements, so viscosity increases strongly with molecular weight.

Step-by-Step Solution:
Evaluate each statement against polymer solution theory.Recognize (d) contradicts the known scaling of viscosity with molecular weight.Choose (d) as the single wrong statement.

Verification / Alternative check:
Empirical Mark–Houwink relations show intrinsic viscosity increases with molecular weight to a positive exponent, confirming (d) is false.

Why Other Options Are Not Wrong:
(a) Networks resist dissolution.(b) Solubility aligns with solubility parameter proximity.(c) Larger solvent molecules reduce activity and diffusion, decreasing swelling.

Common Pitfalls:
Assuming polymer solutions behave like low-molecular-weight liquids; ignoring entanglement effects.

Final Answer:
Very high-molecular-weight polymers give solutions of very low viscosity on dissolving.