Soap solution used for cleaning purpose appears cloudy. This is due to the fact that soap micelles can-

Soap molecules are sodium or potassium salts of long-chain carboxylic acids that form structures called micelles in water [2]. These micelles are association colloids with particle sizes typically ranging from 1 to 100 nm. Because the size of these micellar particles is large enough to interfere with visible light, they exhibit the Tyndall effect by scattering light [1]. This scattering of light makes the soap solution appear cloudy or milky rather than clear. While refraction involves light bending as it passes through different media [4], and diffraction involves bending around obstacles, the specific phenomenon of a colloidal dispersion appearing cloudy due to the redirection of light by suspended particles is defined as scattering [1]. This property is a hallmark of colloids, distinguishing them from true solutions where particles are too small to scatter light.

Sources

1. [2] Science , class X (NCERT 2025 ed.) > Chapter 4: Carbon and its Compounds > Activity 4.10 > p. 75
2. [1] Science , class X (NCERT 2025 ed.) > Chapter 10: The Human Eye and the Colourful World > 10.6.1 Tyndall Effect > p. 169
3. [4] Science , class X (NCERT 2025 ed.) > Chapter 9: Light – Reflection and Refraction > Activity 9.10 > p. 147