Q.Which of the following is γ-isomer of BHC?
a. DDT
b. lindane
c. Chloroform
d. Chlorobenzene

Two closely related green-chemistry principles concern making the synthesis route and the chemicals themselves safer. Less hazardous chemical synthesis calls for designing reactions and synthesis routes to be as safe as possible so that hazardous waste formation is avoided -- illustrated by the insecticide DDT (dichlorodiphenyl trichloroethane), once effective against typhoid- and malaria-carrying mosquitoes but later found to be broadly harmful to living things, being replaced by benzene hexachloride (BHC), whose gamma isomer is called gammexane or lindane. Designing safer chemicals goes further, developing products that are inherently less toxic or that need less toxic raw materials, to protect chemical-industry workers from toxicity exposure -- illustrated by adipic acid, widely used in the polymer industry, traditionally made from carcinogenic, air-polluting benzene, but synthesised enzymatically from glucose instead in a green technology developed by Draths and Frost. Both principles show the same underlying strategy: redesigning a synthesis route or its target chemical, not just cleaning up after the fact, to cut hazard at the source.