Q.What are natural and synthetic polymers? Give two examples of each type.

Natural polymers are polymers found in nature, in plants and animals. They are produced by biological processes and typically serve a structural or storage role in living organisms.

Examples: cellulose (found in plant cell walls, a polymer of glucose) and natural rubber (cis-1,4-polyisoprene, obtained from the latex of the rubber tree). Proteins and starch are other natural polymers.

Synthetic polymers are man-made polymers, prepared in the laboratory/industry from simpler chemical monomers, and do not occur naturally.

Examples: polythene ($-[-CH_2-CH_2-]_n-$, from ethene) and nylon 6,6 (from hexamethylenediamine and adipic acid). PVC and Buna-S rubber are other synthetic examples.

Define natural vs synthetic by origin (biological vs man-made), then supply two well-known examples of each from the chapter.

• Calling a semi-synthetic polymer (like vulcanised rubber) purely 'natural' — vulcanised rubber is a chemically modified form of the natural polymer.
• Not giving two distinct examples per category as asked.
• Confusing rayon (semi-synthetic, from cellulose) with a purely synthetic polymer.