Which one of the following substances is NOT synthetic?

Question

UnlockIAS · Accepted Answer

Correct — A, Fibroin. Fibroin is a natural fibrous protein — the structural core of silk secreted by silkworms (and spiders) — so it is not man-made. The other three are all synthetic polymers: Lexan (polycarbonate), Neoprene (polychloroprene rubber) and Teflon (PTFE) are industrially manufactured. Hence the non-synthetic substance is fibroin.

Why the other options are wrong — (b) Lexan is a trade name for polycarbonate, a synthetic thermoplastic used in shatter-resistant sheets and lenses — man-made, not natural.  (c) Neoprene is polychloroprene, a synthetic rubber (the first commercial synthetic rubber, 1930s), used in wetsuits and gaskets.  (d) Teflon is polytetrafluoroethylene (PTFE), a synthetic fluoropolymer used as a non-stick coating.

Concept: Polymers are either natural — made by living organisms, such as silk fibroin, cellulose, wool and natural rubber — or synthetic, i.e. manufactured, such as nylon, PTFE, polycarbonate and neoprene. Fibroin is a natural animal protein fibre, whereas Lexan (polycarbonate), Neoprene (polychloroprene) and Teflon (PTFE) are all industrially synthesised.

State PCS 2020 Q109 — Science & Technology PYQ with Answer

State PCS 2020 Q109 — Science & Technology PYQ with Answer