Polymer identification via condensation and monomer features

Steps:

• Condensation polymerization forms polymers by eliminating water, typical for polyamides and polyesters.
• Exclude polyesters, leaving polyamides like nylons as candidates.
• Require monomers with exactly six carbons each; nylon 6,6 uses hexamethylenediamine (C6) and adipic acid (C6).
• Match partial structure to nylon 6,6 repeating unit: -[NH-(CH2)6-NH-CO-(CH2)4-CO]-.

Why C is correct:

• C shows amide linkages (-NH-CO-) from two C6 monomers, defining nylon 6,6 per condensation polyamide formation.

Why the others are wrong:

• A: Ester linkages (-CO-O-) indicate polyester, violating "not a polyester."
• B: Single C6 monomer (e.g., caprolactam) forms nylon 6, but question specifies plural monomers.
• D: No condensation linkages; resembles addition polymer like polyethylene.

Final answer: C