Which of the following does not lower the surface tension of liquids ?

ANS:A - Fat

Fat does not typically lower the surface tension of liquids. Surface tension is a property of liquids that arises from the cohesive forces between molecules at the surface. Substances known as surfactants are specifically designed to lower surface tension by disrupting these cohesive forces. Surfactants have a hydrophilic (water-attracting) end and a hydrophobic (water-repelling) end, allowing them to interact with both water and oil-based substances. While fats and oils can act as surfactants in some cases, they are not as effective at reducing surface tension as dedicated surfactants like soap or detergent. Fats and oils are more commonly used for their lubricating properties rather than their ability to lower surface tension. Therefore, of the options provided, fat is the substance that does not typically lower the surface tension of liquids.