The following organic compounds are polymers except

Analyze the question: We are asked which compound is NOT a polymer. A polymer is a large molecule made from many repeating small units (monomers) joined together.

Explain the concept:

• Rubber (natural rubber) is a polymer of isoprene units (polyisoprene).
• Starch is a polymer of glucose units joined by glycosidic bonds (a polysaccharide).
• Proteins are polymers of amino acids joined by peptide bonds.
• Fats are esters formed from one glycerol molecule and three fatty acid molecules (triglycerides). They are large molecules, but they are not made of long chains of repeating monomer units, so they are not true polymers.

Step-by-step solution:

1. Rubber: repeating isoprene units, so it is a polymer.
2. Starch: repeating glucose units, so it is a polymer.
3. Proteins: repeating amino acid units, so it is a polymer.
4. Fats: a single glycerol joined to three fatty acids, with no repeating chain, so it is not a polymer.

Answer: D. fats

Exam tip: Remember the monomer pairs: rubber → isoprene, starch/cellulose → glucose, proteins → amino acids, polythene → ethene. Fats and oils are esters (triglycerides), not polymers. When you see "except" in a polymer question, look for fats and oils.