Which one of the following statements about the cleansing action of soap is not true?

The cleansing action of soap involves the formation of micelles, which are spherical structures where the hydrophobic carbon chains interact with oil and the ionic ends face outward [1]. Consequently, oil and dirt are collected in the center of the micelle [4]. Because micelles are large enough to form a colloidal solution, they scatter light, a phenomenon known as the Tyndall effect. In hard water, soap reacts with calcium and magnesium ions to form insoluble precipitates called scum, which reduces its effectiveness [4]. However, statement 3 is incorrect because soaps are specifically sodium or potassium salts of long-chain carboxylic acids [4]. It is detergents, not soaps, that are often ammonium salts (such as quaternary ammonium salts with chloride or bromide ions) or sodium salts of sulfonic acids [4].

Sources

1. [1] Science , class X (NCERT 2025 ed.) > Chapter 4: Carbon and its Compounds > Activity 4.10 > p. 75
2. [4] https://www.sciencedirect.com/topics/materials-science/soaps-detergent
3. [2] Science , class X (NCERT 2025 ed.) > Chapter 4: Carbon and its Compounds > Activity 4.12 > p. 76
4. [3] Science , class X (NCERT 2025 ed.) > Chapter 4: Carbon and its Compounds > CH COOH CH CH OH CH C C CH CH H O 3 3 2 3 2 3 2 Acid O (E - + - - - - - + thanoic acid) (Ethanol) (Ester) O > p. 73