The following compounds are condensation polymers except

Step 1: Analyze the question We are asked which compound is NOT a condensation polymer. So three options are condensation polymers, and one is not (probably an addition polymer).

Step 2: The concept

• Condensation polymerisation: monomers join together and lose a small molecule (usually water, or HCl) at each linkage.
• Addition polymerisation: monomers with a C=C double bond join together with no loss of any molecule. Nothing is lost, so the polymer has the same empirical formula as the monomer.

Step 3: Check each option

• A. Nylon: It is made from a diamine and a dicarboxylic acid (or diacid chloride). Water (or HCl) is lost as the amide links form. This is a condensation polymer (a polyamide).
• B. Protein: Amino acids join through peptide bonds (-CONH-), and water is lost at each link. This is a condensation polymer.
• C. Starch: Glucose units join through glycosidic bonds, and water is lost at each link. This is a condensation polymer.
• D. Polyethene: It is made from ethene, CH₂=CH₂, by opening the double bond:

n CH₂=CH₂ → -(CH₂-CH₂)ₙ-

Nothing is eliminated, so this is an addition polymer.

Step 4: Answer Polyethene is the only one that is not a condensation polymer.

Exam tip: Remember that condensation polymers lose water, and the natural ones are built from sugars (starch, cellulose), amino acids (proteins). Synthetic ones to remember are nylon and terylene. Addition polymers come from alkenes: polyethene, PVC, polystyrene, and perspex. If the monomer has C=C, think addition.