2013 · Q12
12. Dirty cloths containing grease and oil stains are cleaned by adding detergents to water. Stains are removed because detergent:
General KnowledgeChemistry
- AReduces drastically the surface tension between water and oil
- BIncrease the surface tension between water and oil
- CIncrease the viscosity of water and oil
- DDecreases the viscosity in detergent mixed water
Explanation
Detergents lower the water-oil surface tension to remove grease; the official key marks A.