JEE Main · 2021 · 20 Jul 2021 · Shift 1 · Environmental Chemistry

Green chemistry asks for processes that avoid toxic reagents and leave no harmful residue. Liquefied carbon dioxide dissolves greasy soil, is non-toxic and non-flammable, and is recovered and recycled at the end of each cycle, so it replaces tetrachloroethene, a chlorinated solvent that contaminates groundwater and is carcinogenic. Bleaching paper with chlorine leaves chlorinated organic effluent, and washing with large volumes of water merely wastes a resource without removing the pollutant. The day-to-day application of green chemistry is the use of liquefied $\mathrm{C}{\mathrm{O}}_2$ for dry cleaning of clothes.