JEE Main 2021 · 25 July · morning · Single correct · +4 / −1
Which one of the following chemical agent is not being used for dry-cleaning of clothes?
- (a) H₂O₂
- (b) CCl₄
- (c) Liquid CO₂
- (d) Cl₂C = CCl₂
Answer and solution
Answer (a) H₂O₂
Solution
Chemistry ma’am · 3 steps
Dry cleaning means cleaning without water, so look for the agent that is not a grease-dissolving solvent.
- What dry cleaning needs. Dry cleaning removes oily and greasy stains with a non-aqueous solvent instead of water. So every true dry-cleaning agent here must be a solvent that dissolves grease.
Agent What it is Role in cleaning H₂O₂ an oxidising agent, used as an aqueous solution bleach in ordinary laundry, not a dry-cleaning solvent CCl₄ chlorinated organic solvent an early dry-cleaning solvent, now avoided because it is toxic Liquid CO₂ non-polar solvent under pressure the green dry-cleaning solvent, used with a suitable detergent Cl₂C=CCl₂ tetrachloroethene (perchloroethylene) the classic dry-cleaning solvent - Where H2O2 fits. H₂O₂ does not dissolve grease. It removes colour by oxidation, which is why green chemistry recommends it, with a catalyst, as a bleach for laundry in place of chlorine.
- So. The agent not used for dry cleaning is (a), H₂O₂.
The idea to keep. Dry-cleaning agents are grease-dissolving solvents: CCl₄, tetrachloroethene, and now liquid CO₂. H₂O₂ belongs to the bleaching list, not the solvent list.
Answer from the NTA final answer key. Solution by PrepWiser.